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Want to "Fix" your SMG? Look Here!

132K views 106 replies 55 participants last post by  dtebh916 
#1 · (Edited)
There are many many issues that can arise with the SMG/SMGII. This thread is aimed at one specific, common issue that leaves many SMG owners timid to drive on hot days.

Here are the symptoms:

On hot days with little air flow through the engine bay IE traffic situations, the SMG and SES light illuminate and soon after, the gears drop out into 0 or nuetral. Very dangerous situation at times and for many is guaranteed to happen daily while others only happens a couple times a year.

I have found the cause of this to be a horrible design flaw of the SMG HYD Pump temp sensor being mounted way too close to the engine. As a result, while you are sitting in traffic (with no airflow to cool it off it gets hotter and hotter) the HYD Pump temp sensor picks up heat from the engine and sends a signal to the ECU telling it the HYD fluid is "too hot." This is not the actual case. The result is the circuit that tells your pump to charge the accumulator is momentarilly disabled. You have two or 3 shifts left in the accumulator and after that there is not enough pressure to make the next gear so it drops to nuetral. after about 15-30 seconds the circuit is momentarilly restored and the accumulator charges again...the cycle repeats over and over again untill you can get on the highway or just simply shut the car off and let it cool for at least half an hour.

To stop this problem from happening i experimented and read through schematics for 3 days and what i came up with worked for me and it also worked for another member of this forum whom i was sharing ideas with. The best part is it it costs about 5 bucks if you do it yourself.

Take a 500-1K ohm heat resistant resistor and splice it in series with the temp sensor. its that simple. it takes about 20 Minutes start to finish. i waited about a week to post this to make absolutly sure the problem was gone. you can access the connector that goes from the ECU to the HYD pump from unterneath the car just "inboard" of the front driver side tire. there are 18 wires on it i think and all sorts of colors. the wire you want is the SOLID WHITE WIRE. Just cut it, splice in the resistor and wrap it up tight and your done.

Now keep in mind that this does not keep your car from heating up the actual sensor but instead, adds a temp "bias" for your ECU to not allow it to reach the over temp voltage. This in my opinion is safe, effective and a dream come true for the price. Remember, the only possible effect of hyd fluid over heating is premature wear of the pump itself...chances are if you have this problem, you were told you need to replace the pump by the mechanics for about $3500...Sounds like we have nothing to lose right? Especially since the hyd fluid isnt really overheating in the first place and its just the engine heating up the sensor that is aprox 3/4'' away from it.

Below are some pics of the procedure as i did them on my M. Enjoy. And have a great summer this year without fear of having your Bimmer look like a turd on the side of the road or blocking traffic.:pimpin:

EDIT:
CNTRVSY's Thread on M3F: http://www.m3forum.net/m3forum/showthread.php?t=372262
 

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#78 ·
I went through this exact problem with my E46 2008 M3. Here are my 2 cents and solutions.

My problems popped up around 65k miles around 90 degree heat. The cog would pop up and eventually shift me out of gear. Sometimes the car would turn off in the middle of a highway and I would have to roll to the side to restart. When this happens there is a 80% chance your pump is dying and 20% chance it is something else. If its something else any knowledgeable bmw tech will discover the problem while changing your SMG pump. The resistor mod is not a long term solution, it just prolongs the inevitable, however when your SMG pump is not working the way it should and is slacking, it may screw up your clutch or flywheel or the rest of the transmission. I drove the car on the bad pump through the winter without a problem and had the pump replaced. Since then the SMG worked without a problem and cog never game on and last year i was driving it in 100+ degree weather without a hitch.
 
#79 ·
Seems to have worked for me.

I have a 75,000 m M3 E46 convert, driving away from being parked for 3 hours, warm, but not hot night. Drove 2 blocks, I got the yellow gear solid, no flash, check engine light, slipped out of gear. Turned it off, and back off. While parked, used Elm wifi device (about $14 on Amazon) and pulled a P1717 code. No other codes to speak. Looked safe enough to try to drive home.

got it to drive home (3 miles) then looked at 3 different iOS apps and saw the same P1717 code. Decided to kill all codes, (which is an issue for my upcoming smog check) and ran the car for a bit.

Then the next day, in hot weather, drove about 1/2 mile, same thing; gear and slipped out of gear. But turned it off and on, code disappeared on its own, drove and parked.

Spent 4 hours reading all the forums, and compiling info.

Steps:
Ear in left wheel well, listened as I turned off the alarm. I heard 3 pumpings, about 5 seconds worth. Figured it might be low on fluid. Checked the reservoir, and it was slightly warm engine, but it was at MIN, half way to MAX.

So, I drive to closest auto part store, O'Reily, and bought the pentosine chf11, and ordered a Salmon Relay, (40 min delivery time).

Used a hex I borrowed from them, and after filling up the reservoir, (didn't take much, I might have over-filled) and cleaning all the caps and edges. I replaced the salmon receiver. ($15 bucks at O'Reily ($30+ at the dealer)) and then cleaned up everything, and so far so good.

I did NOT reset the codes again, but the P1717 and other errors codes do not show up on any of my diagnostic apps.

Will drive the car progressively harder, but hopefully it will keep running. Because I wasn't getting the 3-4 issue, no bad sound, and because there were no other symptoms, I believe it was the fluid level in heat. Changing the salmon relay didn't hurt. Will order like most suggest to keep in rear trunk car kit.

Thanks to all on the forum. It cost about 40 bucks, but could have cost much more just for the eval at any service location. Will post my notes below for what many very smart people posted. Think of it as a nice review of all of the things I thought were the most important. - Hope it helps.
 
#80 ·
=========== These are my notes==================================

The dealer called today and said that their was a recall campaign out for my car and part of the recall involves reprograming the SMG control module, so they will do it for free. They will also reprogram the engine module. The mechanic said the purpose of the recall was to improve the communication with the modules. The recall is covered under bulletin 121106. I will see if I can get any more info on that campaign.

BMW Relay (Multi-purpose) (Salmon Red) - Genuine BMW 12631742690

Read more: http://www.eeuroparts.com/Parts/29348/Relay-Multi-purpose-Salmon-Red-12631742690/#ixzz3gewrBGUP
Fix your European car with us at eEuroparts.com, your trusted supplier of European auto parts since 2000.
Follow us: @eEuroparts on Twitter | eEuroparts.com on Facebook

P1717 - SMG Hydraulic issue ***8212; It's usually triggered by the hydraulic unit overheat sensor.
P1717: SSD Inductive Signature Malfunction, and others have said it has to do with Hydraulic Pump is on period due to out of range operation short circuit.

known fixes and nothing is helping. I changed the relay twice, added Pentosin, replaced the battery (hydraulic oil (pentosine chf11)

Check your SMG fluid reservoir. Make sure it is full.

Problem fixed!.....

I Did two things, changed the SMG relay and filled up the SMG fluid reservoir with Pentosine. When I first changed the Relay the SMG light went away but the SES light was still on. Then I added more hydraulic fluid and cleared the error codes. After 2 starts the SES light went away, drove the car went through all the gears and all shift programs and car works great.

Total cost was ~$30 and took less than an hour.

Turns out it was the SMG relay switch. But, it also zapped by battery so had to get a new one.


Temp Sensor - Bosch PN# 0280130026 Part numbers I have for the HCU temp sensor are:
VDO part number is 805/9/1. The Bosch part is 0 280 130 026
I think this crosses to generic Bosch part: MTC M12

After looking up the cats on this site, someone had posted about a 80K/8Yr emission warranty. I called them and they agreed to cover the cost of the CATS under that warranty. They also replaced the relay ($346 parts and labor) but credited me 10% off the pump to cover that cost. So I am out $3800 but have a new pump/relay and Catalytic converters/headers.


1k is too much, change your smg relay. Same code here but no gear drops. You need to use a 680ohm to make sure if something does go wrong you are alerted. I changed my resistor and wow. What a difference. I have a spare in my glovebox too now just incase. I'm not being stranded over 12$ lol

immediately noticed it took 3 seconds for the pump to pressurize rather than 8-10.




I ordered a new relay from BMW and it'll be overnighted so I'll have it installed tomorrow. I've done some research and others have fixed the problem with a new SMG relay and added more Hydraulic fluid. After turning the key over twice all sensors go off and problem solved. Hopefully it works!


1) relay
2) SMG rewire technical service bulletin
3) hood sensors
4) inspect fluid level & hoses for leaks etc.
5) compression springs
6) temperature sensor (?)
7) gear position sensor
8) pump
9) actuator
10) from my research the clutch/flywheel/main transmission parts are very robust in these cars, and if a dealer says that's the problem they are grasping for solutions or the car has been driven pretty hard (I never got a good answer why BMW had to open up my tranny)





I may have potentially found a new cure to SMG problems. My 2002 LSB M3 (in the sig) was dropping out of gear while driving, and going back in 5 seconds later. I took it to the dealer, and two other shops, and they diagnosed it as the pump. However, I refused to believe that because it was shifting perfectly (when it wasn***8217;t going out of gear), and it was priming just fine. So after A lot of research and reading numerous threads, I came across a few that mentioned the temperature sensor on the SMG unit possibly malfunctioning. However, I did not find anyone who actually attempted a replacement. So, I did. I ordered the part, took it to a local shop, and replaced it. Also, I lost some fluid, so we added some fresh Pentosin, primed the system, and so far, I am 200 miles trouble free. I am continuing to drive it to test this fix, so stay tuned. The part number is 13-62-1-709-966





I don't have a schematic but, indeed, the wiring harness is located behind the front driver's wheel. Sorry, I don't have video. I did all of this work on my back and after some time taking many pictures was the last thing on my mind.

I had to remove two plastic protective pieces (one beneath the engine and one closer to the front driver's wheel suspension) to gain access to the harness. Removing the wheel should give you access as well. The harness's end screws into a part with a 1/2-turn or so twist; it doesn't rotate too much due to the many wires in the harness.

If you have not changed the salmon-colored SMG relay, I'd do that first. It's easy. This shows where it is and this shows the base.

Back to the harness operation:

Be sure use high-quality ceramic resistors to insulate against the heat. This shows the sizes that we LARGER than the one I eventually used. The harness' diameter is much smaller than I presumed from the pictures in other posts. The one I used was the same brand as the ones in this image but smaller by probably 25% than the smallest in the image.

This is a picture of the crimper I used. This shows the wire stripper and butt connectors I used. The butt connectors' inner diameter varies, so I strongly suggest buying several pairs of variety of sizes because an overly-large connector will not provide a great crimp on the SMG wire. My resistor's wires are greater in diameter than the SMG wire. I also suggest trying the crimper on wires using the intended butt connectors to practice with it (the wires in my picture are thicker than the SMG wire). I had to squeeze extremely strongly to complete the crimp (twice, of course: one for each end) because the plastic must be crushed to connect the 2 wires.

This shows the harness with the white wire cut and stripped. The wire is very thin and somewhat brittle, so be *extremely* careful stripping it and don't handle it more than necessary.

I used high-temperature-rated electrical tape (compare degree ratings) to first seal the connected ends, then the entire portion of the harness that underwent this operation. I don't have a picture of the final state.

==

Salmon Relay" is part #61-36-8-366-646... hydrolic pump relay and is $39.07 in St. Louis (dealer) on 6-28-14. Not just a $5 part like some have suggested. The resistor was a lot cheaper and did the trick for me.


====

There are many many issues that can arise with the SMG/SMGII. This thread is aimed at one specific, common issue that leaves many SMG owners timid to drive on hot days.

Here are the symptoms:

On hot days with little air flow through the engine bay IE traffic situations, the SMG and SES light illuminate and soon after, the gears drop out into 0 or nuetral. Very dangerous situation at times and for many is guaranteed to happen daily while others only happens a couple times a year.

I have found the cause of this to be a horrible design flaw of the SMG HYD Pump temp sensor being mounted way too close to the engine. As a result, while you are sitting in traffic (with no airflow to cool it off it gets hotter and hotter) the HYD Pumptemp sensor picks up heat from the engine and sends a signal to the ECU telling it the HYD fluid is "too hot." This is not the actual case. The result is the circuit that tells your pump to charge the accumulator is momentarilly disabled. You have two or 3 shifts left in the accumulator and after that there is not enough pressure to make the next gear so it drops to nuetral. after about 15-30 seconds the circuit is momentarilly restored and the accumulator charges again...the cycle repeats over and over again untill you can get on the highway or just simply shut the car off and let it cool for at least half an hour.

To stop this problem from happening i experimented and read through schematics for 3 days and what i came up with worked for me and it also worked for another member of this forum whom i was sharing ideas with. The best part is it it costs about 5 bucks if you do it yourself.

Take a 500-1K ohm heat resistant resistor and splice it in series with the temp sensor. its that simple. it takes about 20 Minutes start to finish. i waited about a week to post this to make absolutly sure the problem was gone. you can access the connector that goes from the ECU to the HYD pump from unterneath the car just "inboard" of the front driver side tire. there are 18 wires on it i think and all sorts of colors. the wire you want is the SOLID WHITE WIRE. Just cut it, splice in the resistor and wrap it up tight and your done.

Now keep in mind that this does not keep your car from heating up the actual sensor but instead, adds a temp "bias" for your ECU to not allow it to reach the over temp voltage. This in my opinion is safe, effective and a dream come true for the price. Remember, the only possible effect of hyd fluid over heating is premature wear of the pump itself...chances are if you have this problem, you were told you need to replace the pump by the mechanics for about $3500...Sounds like we have nothing to lose right? Especially since the hyd fluid isnt really overheating in the first place and its just the engine heating up the sensor that is aprox 3/4'' away from it.

Below are some pics of the procedure as i did them on my M. Enjoy. And have a great summer this year without fear of having your Bimmer look like a turd on the side of the road or blocking traffic.

EDIT:
CNTRVSY's Thread on M3F: http://www.m3forum.net/m3forum/showthread.php?t=372262


ceramic NTE 10W233, 3.3K Ohm Flameproof Resistor 10W 5% Pkg of 2 for $0.99 ! what a deal.
Ceramic Cement Power Resistor 20W 3K ohm
Size:61mm X 12mm X 12mm (Approx)


====


1... disconnect battery, give a trickle charge if you have time
2... open bonnet and free off /or replace bonnet switch ( it sticks and can cause gear light to flash and stop car from starting or cause limp home if you are driving) easy fix... easy missed...
3... open up the relay and dme brain box up at the passenger bulk head under bonnet ..4 allen bolts and change the salmon relay part no SMG relay is 12631742690... cost £ 5.27 from the dealer
4... reconnect battery, close bonnet and lock and unlock the car , make sure the bonnet is defo closed and all doors and boot, go in start car.. gear light can remain lit and selector display flash... go take car for quick road test, and all should be ok - lights will jump to solid with no flash.. smg and eml light will go out if all is well after 2 drive cycles

====
I wouldn't look to the fluid as a problem. The Min/Max lines are usually a safety. A little below or above said lines will not make a difference.



\\\


I did the 680ohm mod
he original 3.3k would have let my pump torch itself inside out for sure. So if you haven't changed yours to a 680 DO IT!

part number

10 watt 3.3k ohms 2pc/pk
power wirewound resister
tol=5% voltage = 550v

768249087823
Fry's available to you, I'd go there and get the ceramic encased type. Just added comfort/ peace of mind knowing that the resistor is more secure from the elements.

===
Frys.Com Link













On side note, I think I have been having a faulty outside temp sensor. Its currently reading -40 degree outside lol. However I have not seen any related problem because of faulty temp sensor.
Hot temp outside, sit and go traffic driving for over 2hours could be result of my car acting up

====

The manual says "at a speed of over 20 mph" and you only have to hold the paddles back for "approx. 2 seconds."

When I do this, I take my foot off the accelerator so there is no engine revving.

This is also something you don't have to do. The system will learn it gradually while driving.



I would replace the relay if it hasn't been done already and then the gear position sensor since they could be pretty cheap fixes. Check the fault codes with the GT1 first.


It sounds like your pump isn't holding pressure, 4 minutes in between activations is too soon.


BMW have an SMG calibration program they can run that may clean up SMG operation when doing an SMG software update. It runs through all the gears, clutching and declutching, measuring and storing actual operating data. Runs with motor off, battery hooked on a charger and the diagnostic computer runs the SMG system. Takes about an hour to run. SMG software can only be updated something like ten times, after which the storage module must be replaced which can be expensive, so don't update software more than necessary to correct a problem.


I'm going to order a relay from Tischer tomorrow first thing and try to get them to overnight it to me. After reading several threads, I also notice a common theme that the key becomes sporadic or just downright weak. Mine has been weak since I got it, not working outside of 8 or so feet. Also, I believe it's important that I can still hear the pump making noise when I unlock the car. The SES light isn't on.

changed the SMG reservoir fluid and cleaned out the gunk built up around the reservoir caps (small and big).

GEAR POSITION SENSOR"


The attempted fixes and diagnostics: Codes were pulled first, aside from 056, I forget the other 1 or 2...
1. Salmon Relay Replaced - No change
2. Topped off fluid - No change
3. Updated to latest SMG software - No change
4. Replaced the Transmission fluid - No change
5. Replaced the SMG computer, reprogrammed - No change
6. Armand monitored pressure while driving the car... Noticed pressure was dropping below 50 bar (this is the number if I'm remembering correctly), a point at which the SMG pressure sensor would typically tell the pump to engage and "refill" pressure. Armand suggested a unit replacement.
7. Before succumbing to the full unit replacement, I asked him to try one more thing... Disabling the HCU temp sensor. Armand did so, and drove the car over the weekend. Although he notice a little improvement, he still had issues with pressure as he monitored the car.
8. Armand was able to install a bypass switch. When he noticed the car had dropped below the necessary pressure, he could hit the switch and the pump would engage immediately, bypassing the "sleeping" pressure sensor. The use of this switch basically alleviated my issues.



drivers side door actuator is bad, it will have your transmit-ion shift to N at a stop while in traffic or at a light.... because it is assuming that you have your door open and it is popping it out of gear.

smg manual and in the troubleshooting guide it mentions multiple times to verify that the battery is over 10V. So now I was praying that it was my battery, took out my voltmeter to check and it measured 12.5V...rats...ok ruled that out.


gear position sensor that's buggered. Pt # 23 41 222 9792





There are many many issues that can arise with the SMG/SMGII. This thread is aimed at one specific, common issue that leaves many SMG owners timid to drive on hot days.

Here are the symptoms:

On hot days with little air flow through the engine bay IE traffic situations, the SMG and SES light illuminate and soon after, the gears drop out into 0 or nuetral. Very dangerous situation at times and for many is guaranteed to happen daily while others only happens a couple times a year.

I have found the cause of this to be a horrible design flaw of the SMG HYD Pump temp sensor being mounted way too close to the engine. As a result, while you are sitting in traffic (with no airflow to cool it off it gets hotter and hotter) the HYD Pump temp sensor picks up heat from the engine and sends a signal to the ECU telling it the HYD fluid is "too hot." This is not the actual case. The result is the circuit that tells your pump to charge the accumulator is momentarilly disabled. You have two or 3 shifts left in the accumulator and after that there is not enough pressure to make the next gear so it drops to nuetral. after about 15-30 seconds the circuit is momentarilly restored and the accumulator charges again...the cycle repeats over and over again untill you can get on the highway or just simply shut the car off and let it cool for at least half an hour.

To stop this problem from happening i experimented and read through schematics for 3 days and what i came up with worked for me and it also worked for another member of this forum whom i was sharing ideas with. The best part is it it costs about 5 bucks if you do it yourself.

Take a 500-1K ohm heat resistant resistor and splice it in series with the temp sensor. its that simple. it takes about 20 Minutes start to finish. i waited about a week to post this to make absolutly sure the problem was gone. you can access the connector that goes from the ECU to the HYD pump from unterneath the car just "inboard" of the front driver side tire. there are 18 wires on it i think and all sorts of colors. the wire you want is the SOLID WHITE WIRE. Just cut it, splice in the resistor and wrap it up tight and your done.

Now keep in mind that this does not keep your car from heating up the actual sensor but instead, adds a temp "bias" for your ECU to not allow it to reach the over temp voltage. This in my opinion is safe, effective and a dream come true for the price. Remember, the only possible effect of hyd fluid over heating is premature wear of the pump itself...chances are if you have this problem, you were told you need to replace the pump by the mechanics for about $3500...Sounds like we have nothing to lose right? Especially since the hyd fluid isnt really overheating in the first place and its just the engine heating up the sensor that is aprox 3/4'' away from it.

Below are some pics of the procedure as i did them on my M. Enjoy. And have a great summer this year without fear of having your Bimmer look like a turd on the side of the road or blocking traffic.


heard from a mechanic... that the pump has to be changed to do a complete flush. But, I was told that changing the reservoir will make the new fluid to circulate thru the system. My old reservoir fluid was near black/tea color compared the new fluid in clear green.. I will check the new reservoir color soon to see if the current reservoir color has changed away alot from clear green. If it did, then it can be a sign that the new reservoir has fully circulated thru the system and mixed with the old fluid... and replace it with new fluid since I still have a lot left from a 25 bucks bottle. Very cheap DIY and zero modification to be a trial before resistor DYI in my opinion





Might want to make sure your gear position sensor isn't being over heated by the cats.
If your Gear Position Sensor goes bad the tranny will start shifting into 2nd to take off and my not use 6th gear. If it drives normal in auto mode I would think it's something with the manual shifting input sensors.



Found this issue with my SMG and I fixed it, the problem were while i was driving the gear indicator light would flash at ALL times, when I came to a stop and release the brake pedal the transmission would shift to N and still blink, then I would have to place it back into gear, BUT.....If i kept the brake pedal on and hard the gear indicator would still flash but not jump out of gear, then while driving the COG light would illuminate and I would reset it with my Autoenginuity tool, the other problem that was having was that my PDC wouldn't work, so the fix was both Hood sensors (51237893575), the 2 that are on the front of the car that locks the hood in place. Once I changed those 2 out 2 days ago, no more issues and runs perfect!! PDC no issues!

Previous to this problem, my gears would skip and jump out gear and the problem was the Gear identification switch (23412229792). With all this said I changed the Salmon Relay just in case.





1) Pump out the old fluid from the SMG reservoir as shown in the picture that I found below with a siphon pump. The reservoir is label with Pentosin CHF 11S
2) Clean out the gunk on the small and large caps
3) Refill the reservoir with a new Pentosin CHF 11S (power steering fluid) - about $25ish at Autozone - picture shown below.
Extra) Topped the coolant.
1st UPDATE: light didn't come on for the first few days under 90-105 temperature - only local driving (no highways) and parked in a parking lot with the engine and AC on for while I was getting a Starbucks coffee.
Engine and Oil temperature: both below the half line.
2nd UPDATE: light came on once or twice after first few days after highway on local streets under 90-105 outside temperature. However, the gear never popped out, which is good. Eventually, the light went out after parking in a garage and highway driving.
Engine and Oil temperature: one of them was over the half line. I forgot which one it was.



DIY: The "Standup" SMG Resistor Mod
http://m3forum.net/m3forum/showthread.php?t=414499

DIY: SMG Resistor Mod
http://www.m3forum.net/m3forum/showp...&postcount=191

http://www.m3forum.net/m3forum/showp...&postcount=216

http://www.m3forum.net/m3forum/showp...&postcount=217

680 Ohm Resistor
http://www.radioshack.com/680-ohm-1-...l#.VPkk2Ckmjp4









Installed a resistor on of our Ms and it worked for a month or so, pump basically died (wouldn't hold pressure). What this resistor mod is doing is fooling SMG DME, and therefore pump will stay on until fluid and motor on the pump overheats, similar to bleeding procedure. Installing a resistor almost guarantees imminent SMG pump death.

You can get all CHF fluid out of the system by disconnecting slave cylinder line, and taking out the relay. Pump will prime out most of the fluid out. You will need INPA, ISTA or Autologic tools to bleed the system again. Fluid flush however, will not help the situation.

Accumulator gets worn out causing motor to run until fluid overheats thus killing the motor in process. I've recently rebuild a pump with new accumulator and had Eurton Electric rewind the motor. Replaced temp sensor with E36 block sensor and its been running like a champ since then with no resistor.






More than likely the SMG failures are due to corroded o-rings or seals. Hence the reason for the failure diagnostic reading "high pressure/low pressure". Probably bits of eroded rubber grommets find their way into the system and plug it up....which would give the car the "bucking bronco" ride as it partly engages and disengages the clutch. Just like if you were pressing a clutch pedal in and out while driving in traffic.

Or it could simply be the pump motor unable to prime the system to full pressure, therefore the inadequate pressure would cause the same effect.
Unfortunately BMW does not sell just the motor separately, just the accumulator.

http://www.realoem.com/bmw/showparts...74&hg=21&fg=10

http://www.realoem.com/bmw/showparts...75&hg=21&fg=10




springs that acctually depresslocated in the unit(forget if it was for gear secection or not) was broken it was a $2 dollar part but it was a ***** to get to. Ill see if i can find the thread, it was recent.








The hydraulic unit is filled with .45 L Pentosin CHF 11S fluid and operates at a working pressure
of 45-80 Bar.
The hydraulic units consists of the following components:
***8226; Aluminum Housing
***8226; Electro-Hydraulic pump with filter
***8226; 18 pin electrical connector
***8226; Pressure accumulator and non-return valve
***8226; Pressure relief valve
***8226; Oil pressure sensor
***8226; Oil temperature sensor
***8226; Fluid Expansion tank
***8226; Proportional directional valve for clutch control
***8226; Proportional directional valve for selector shaft angle control
***8226; Pressure control valve for shift travel cylinder actuation


Hydraulic Pump
The Hydraulic Pump, installed in the Hydraulic unit, generates the pressure required to
operate the clutch and perform gear changes.
The pump is a piston pump driven by an electric motor, actuated by the SMG control unit
via a relay so that oil pressure is always between 45 and 80 bar. Power consumption of the
electric motor is 20 amps.
When the fluid pressure in the hydraulic unit drops below 45 bar, the SMG II control unit
activates the relay and supplies the electric motor with B+. At a hydraulic pressure of 80
bar, the SMG II control unit deactivates the relay.
To ensure there is sufficient pressure when the engine is started, the hydraulic pump is activated
below an accumulator pressure of 45 bar when the door is opened or the vehicle is
unlocked with the key or the remote.
In the event of a hydraulic system failure the gearbox warning lamp is turned on in the IKE
and if hydraulic pressure fails to build, no further gearshifts are allowed. This allows the
reserve pressure in the accumulator to be used to place the gearbox in the Neutral position
when the vehicle comes to a stop.
Pressure Accumulator and Non-Return Valve
The Pressure Accumulator in the hydraulic unit ensures that pressure generated by the
pump is stored in the system for a certain amount of time. The accumulator is divided into
two chambers by a piston, with nitrogen at 39 bar filling one chamber and fluid delivered
by the hydraulic pump filling the other chamber. The volume of the accumulator is 150ccm.
The Non-Return Valve at the pump outlet prevents the hydraulic oil pressure from dropping
when the pump is not running.
Pressure Relief Valve
The Pressure Relief Valve opens if the hydraulic oil pressure reaches 100 bar, creating a circuit
between the suction and pressure sides of the pump, thus preventing further increase
in pressure.
Hydraulic Oil Pressure Sensor
Mounted on the hydraulic unit the Oil Pressure Sensor informs the SMG II control unit of the
current hydraulic pressure. At 0 bar pressure a voltage signal of .5 volts is sent to the SMG
II with the voltage increasing linearly to 4.58 volts at 100 bar of pressure.
Failure of the pressure sensor whether shorted or open will result in the hydraulic unit being
activated for a fixed amount of time at predetermined intervals and after each gearshift to
maintain system pressure.
Hydraulic Oil Temperature Sensor
Temperature of the hydraulic oil is monitored by the SMG II control unit via a NTC temperature
sensor located in the hydraulic unit.




His buddy (sorry, don't have the direct contact) rebuilt my pump and Gino only charged me the $800 cost his buddy charged him and labor to install and calibrate/program. It was all done in 3 days too. From what he said, it is a lot to bleed it correctly (automated system takes 1 1/2 hours) and replace the pump, then reprogram and stuff and he wants me back in 3 weeks so he can check the fluid level and pressure to make sure it's all good and there were no air bubbles in there. The rebuilt pump is working great so far and improved on the car's feel from before there was ever a problem with the pump too. It shifts faster and smoother now and NO JERKING DOWNSHIFT into 2nd anymore, YAYYY!!

Gino is the ONLY one I trust with my M3! He's helped me with a lot over the past year. Inspections are only like $750 there too- beats the $1800 the stealerships out here are charging. I don't work for Gino, I swear, he's just a good guy, true racer himself (check out the car in his shop), and honest mechanic.



Bucking bronco. Look it up, you need to either step on it, let off completely, or shift. This happened to me during the test drive and first month. SMG takes some learning.
 
#81 ·
Temp sensor mod no good??

Would love some help.. Last summer my ride died on a highway trip. No gears, no start.......
Got it into an Indy shop this year, and right way told replace the whole pump assembly. After reading everything I could find about smg, had them pull the pump motor. Motor was cooked, so I sent it to California for a rebuild. Motor back in, shop says it builds 50- -60 bar but drops after. I order new accumulator, and car now appears ok. Spec pressures...but dreaded cog light then service engine light now illuminate.
Code is 1717 pump on time..
After more reads...perform resistor mod with 820 resistor(only size avail).
.1st time out- both dummy lights go out ***128515;. 20c day. No hard driving.
Next day 26c day 1/2 hr highway cruise, stop at a store, start it up, and both cog and engine light again. By the time I get near home, drops out of 2-3 to N ( first time ) then ok.
What is up with my car? I love/hate my car nowadays.
Please help!
 
#84 · (Edited)
Wassup guys, my roommate and I just did this mod on my 2004 M3 SMG. I've been having the same problems described in the post above. The mod installation went very smoothly, although it's a tight squeeze if you don't have high enough ramps/jacks, I decided to go with a 5.6k watt resistor. Its a pretty straight forward job once you find what you're looking for. After we finished the mod, I drove it around town and beat it pretty hard. Usually when I'm driving it like a brick's laying on my foot, I get a sense of when that cog light will coming on. It never came on though! Although I wasn't stuck in traffic anywhere and it wasn't blazing hot, I still feel very confident in my e46 now. Think I just fell back in love with my car lol. I'll give you guys an update when I'm stuck in traffic and its 90+ degrees outside.
 
#85 ·
SMG Problem - jumps out of gear - same symptoms as everybody else.

Any update on your repair/fix?

Have had the problem for last 3 years. Really a PITA when it gets hot. Basically quit driving the car until it gets cooler..

Have replaced salmon relay twice, and ambient air temp sensor. My indy repair shop, who is great, is stumped. No codes, just jumps out of gear as described, engine/oil temps within range. Sometimes have to park car with hood open for 20 minutes or turn off A/C, roll windows down, drive like grandma. Added a little more hyd fluid - wasn't low...but looking for answers. No change.

Saw somebody posting that battery was weak? They replaced, but never posted result?

Thanks,
Ed in East Tennessee

long string of 95+ degree days with high humidity
 
#88 ·
Update on my Resistor Mod

Any update on your repair/fix?

Have had the problem for last 3 years. Really a PITA when it gets hot. Basically quit driving the car until it gets cooler..

Have replaced salmon relay twice, and ambient air temp sensor. My indy repair shop, who is great, is stumped. No codes, just jumps out of gear as described, engine/oil temps within range. Sometimes have to park car with hood open for 20 minutes or turn off A/C, roll windows down, drive like grandma. Added a little more hyd fluid - wasn't low...but looking for answers. No change.

Saw somebody posting that battery was weak? They replaced, but never posted result?

Thanks,
Ed in East Tennessee

long string of 95+ degree days with high humidity
Hey man! I feel your pain. You my friend need to do this mod ASAP! I'm 99.9% sure that you're having the same issue as most m3 smg owners living in hot areas are having. Since I've did the resistor mod I've had ZERO issues with this problem. Like you, usually when it was 85+ degrees outside and I happen to be stuck in traffic, my car would kick outta gear into neutral every
2 min. Embarrassing and annoying as ****. Living in Charleston SC, it gets VERY hot and humid here, so that was happening on the regular for me. And traffic is always bad here in the summer so I HAD to do something about it or just dump the whole transmission for a manual. But since the resistor mod I've been stuck in traffic in 100+ degree weather and still NO issues!

Eventually I may convert to a full manual transmission, but right now I'm loving this SMG!! Its great as long as you're having no problems. If you take your car to the shop to get it diagnose, their just gonna tell your your hydraulic pump is going bad and to replace it. Don't waste your time or money. It's the Temp sensor being so close to the engine. When you're stuck in traffic, your car isn't getting any air flow so that sensor gets activated, causing your cog light to come on and eventually kick the transmission outta gear. Do the mod and you'll be fine!

Love your e46 Again
 
#86 ·
Ed, set your drivelogic to number I. And leave it there. All the time. You can still drive fast. Drive manually, all the time, like you drive stick. Leave some time to the system to work. No slamming gears. When you drive fast, do not leave the throttle off when change, just hold it.
 
#87 ·
I am always in traffic when this happens so no slamming gears. Actually, I rarely slam gears. I usually drive in 'manual' mode and typically drive to conserve gas/limit revs.

Was hoping to get some feedback on weak battery and hearing that replacing the battery made the problem go away. I can't imagine with all the M3's out there, that relatively few have this problem.

.02
 
#89 ·
I had the cog light come on due to a bad battery , I replaced the batt and no more cog light , then found out my car was suffering from a parasitic draw that killed the new battery in 10 days without driving the car , I fixed the amp draw and swapped out the battery under warranty , now no problem with cog light or amp draw , I hope it is as simple as this for you , I have also heard good results from the heat sensor modifications posted above .
 
#95 ·
02 m smg

mine had mod done prior to me getting the car found out wire was broke had to replace , I'm in Fl after 2 months it has started again , had car towed last night , it went in to neutral and never went back into gear on top of that car wont start now ... i'm lucky the shop that works on mine are good Friends, will give you guys an update today to what has caused the not starting probl.
 
#96 ·
New to this thread, live in Hotlanta here. I did the pump relocation to the drug bin, no problem with gear jump out. When I did the relocation, new lines and new fluid. What a difference old vs new fluid. Just as other fluid, it's not lifetime and with 109k miles, the old fluid was old. Smell different, color was much darker. Changing SMG fluid should be a PM item. I did the pump relocation as a PM.
 
#98 · (Edited)
Was having the SMG neutral/temp issue for the last few years during the heat of the summer on my M3. Found my problem, with 167K on the motor, the fan clutch had become insulated with dirt to the point it would not fully engage at idle, consequently insufficient air flow in engine compartment.


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#100 ·
That mis dirt, however the reason the dirt sticks so well is all of the viscous fluid leaked out slowly. Over time more and more dirt stayed attached.

Remove the clutch, be sure to clean the inside of the fan. Replace it.
 
#102 · (Edited)
I replaced the fan clutch due to low flow and mileage (I ordered a replacement prior to removal, not knowing the filth condition of the clutch, I show no oil leak at the shaft seal, back of clutch assembly does not have any dirt build up) the old clutch has the same COLD state resistance as the new one. With the new fan clutch at running temp, it pulls quite a bit more flow than the old dirty one.

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#104 ·
I'm not sure I have the same problem, but definitely the SMS has been a pain when it doesn't work correctly.

A little history. 05 M3 SMS e46 convertible - Owned the car since 60K miles. I have had intermittent problems with the SMS and COG light since about 100K miles. It's now 220K. Love the car, engine is still strong. Would like to keep. Now, my car is immobile, with GOG light on in the driveway. Car drove normally when I shut it off. Battery fully charged. At about 150K miles, SMS problem got so bad, my mechanic said SMS pump was failing. Read about a fix on-line which happened to be replacing the electric motor for the hydraulic pump on the clutch. Purchased and replaced the motor for the pump and the fluids which came with the kit, since pump appeared to be fine. Made an immediate difference, guess the electric motor bearings were shot and wouldn't allow the pressure to build quickly enough when hot/warm to not fail, but now car won't start at all. When attempting to start, I can hear a faint whine (pump running), but the light doesn't go out, car won't start, sitting in driveway.

Thoughts? Southeast US - Knoxville TN
 
#105 ·
A little history. 05 M3 SMS e46 convertible - Owned the car since 60K miles. I have had intermittent problems with the SMS and COG light since about 100K miles. It's now 220K. Love the car, engine is still strong. Would like to keep. Now, my car is immobile, with GOG light on in the driveway. Car drove normally when I shut it off. Battery fully charged. At about 150K miles, SMS problem got so bad, my mechanic said SMS pump was failing. Read about a fix on-line which happened to be replacing the electric motor for the hydraulic pump on the clutch. Purchased and replaced the motor for the pump and the fluids which came with the kit, since pump appeared to be fine. Made an immediate difference, guess the electric motor bearings were shot and wouldn't allow the pressure to build quickly enough when hot/warm to not fail, but now car won't start at all. When attempting to start, I can hear a faint whine (pump running), but the light doesn't go out, car won't start, sitting in driveway.
First you should read the SMG fault memory with Inpa / ISTA-D and observe the real-time hydraulic pressure. This information is the basis for proper troubleshooting. Once you have it, you can contact the SMG Society for help.
 
#106 ·
Hi guys... sorry for going directly to my problem... but after reading most of the topics/questions/answers around here (and many other forums) ... I think here it's the best place to share my issue:

My m3 e46 goes fine (it's a Dec-2002 version), and I got my smgII driving me crazy with a rare issue that is the opposite thay some of you have faced.

From few time ago, the cogs light pops up when ignition... and after some time or mileage done, switch off the car and then re-ignition... the cogs light doesn't appear anymore... after some time parked.

I replaced the temp sensor as per the error message:

39 (0x27)hydraulic temperature
  • Temperature sensor defective
  • Short circuit
  • open circuit

But the issue still persists.

Anyone??

Many thanks in advance!
 
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