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Discussion Starter · #1 ·
Symptoms as they progress:

Sluggish shifting
Starting in 2nd gear on occasion
Gear Cog Light
Eventually only able to use R, 2, 5 and 6.

Why they happen that way:
When the Gear Position Sensor (GPS from here on out), which has 2 sensors in its housing, is not getting a signal from either of its sensors the SMG computer reverts to a fail safe shifting mode. The reason you only get R, 2, 5 and 6 is easy to understand once you look at the layout of the shift pattern on the 6 spd GETRAG. Here's a crude outline:

R-1-3-5
2-4-6

In the upper left you have reverse, with 2nd in the lower most left position, and 5 and 6 down at the other end. Since the transmission can't tell where the selector is at, it simply says "go all the way left and all the way down" or "all the way right and all the way up" Simple enough right?

Recommended tools required:
Set of sockets (metric obviously)
Ratcheting wrenches are also highly recommended.
10mm inverted torx (a 10mm socket will work if you're in a pinch)
4mm Allen Wrench
Jack and jack stands.

Instructions to follow in the next post.
 

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Discussion Starter · #2 ·
Step one: Jack up your car securely.... My driveway does not support jacking a car up very safely, so here's what I ended up with:



You will need to raise the rear tires as well in order to spin the drive shaft - we'll get to that later though.

Many will recommend disconnecting the battery, DON'T disconnect the battery, you need power to the SMG pump in order to shift back and forth between N and 2 - again for removing the drive shaft.

Step 2: Getting straight to work, start taking off the skid plates around the transmission (there are 2 plastic skid plates that should be removed)

Step 3: Exhaust removal. I took out the whole section between the headers and the axle back. Here's what I'm talking about:



You will need to take out the V shaped brace under there and the two chassis braces (should be pretty obvious when you're under there as one of the braces has exhaust supports on it.

Step 4: The heat shield in the above picture also comes out.

Step 5: Here's what you're looking at:



The part you want to replace is above the drive shaft, so start working on the 3 nuts and bolts holding it to the vibration dampener. Also un-bolt the drive shaft support bearing. You do not need to disconnect the drive shaft from the differential.

Here's where the GPS plugs in:




Be careful with the wires getting them around SMG lines.

Step 6: Use your little midget hands to get a 4mm allen wrench up onto the bottom allen screw of the GPS - Like this:



Step 7: Now you may have already tried and failed at getting the top bolt out - that's what you get for not reading ahead. Take your allen wrench and cut about an inch off the long side and then put it into a vice and bend it like so:





Now go try again, and yes it is still a pain, but at least it will be possible.

Step 8: when you have gotten the ten thousandth thread to finally let go, the GPS will slide out fairly easily, like so:



The new one pops in the same way, you may feel a little click. Put in the bottom allen screw first. Make sure it's tight enough to not move. Now go click your key on and shift to N, then back into gear. If the Cog light is off and your tranny shifts to first I have some good news.

Finish putting everything back together and have fun!
 

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Discussion Starter · #5 ·
Glad you guys like it... Hopefully it will save some of you some cash. Also did a Water pump DIY, but there seem to be plenty of people out there that are capable of doing that. As for SMG stuff, if you ever have an issue with yours, PM me I read the hundred and some odd page technical manual from BMW on it and have a pretty good handle on troubleshooting them.
 

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Your a god bro next time your in Dublin the beer is on me. I owe u. Gonna it this part tomorrow
 

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Discussion Starter · #12 ·
No luck as of yet. I have been shifting focus slightly to learning the GT1/DIS/SSS/PROGMAN stuff. If I come across it again I'll post it here.
 

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Hey just had a look through your post here and you seem to know what your talking about with SMGs. Wondered if you could help me. I have a 325ci m sport 5spd SMG/SSG. Basically I have been having this re occouring problem where I will be driving and there will be a 4/5 second delay between gear changes and clutch will slip on pull away no cog light nothing then after finishing the journey car goes off leave it a while drive again its perfect :/ weird eh?Few places have said the clutch but if its the clutch how can it be perfectone minute then terrible the next? Seems to be after long drives or if I have others in the car when im on my own just driving to work and home its fine.

Please any help or advice would be brilliant!

Thanks
 

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Well just in case anyone in the future runs into the same problem I did, if your tranny doesnt want to take all gears after replacing the gps, you probably need to run the full transmission adaptation on it. I had an issue where I could not engage gears 2-4-6 when the car was cold after replacing my gps. Ran "adapt transmission fully" with gt1 and it was back to normal.
 

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Hi, just one question can bad gear position sensor burn your clutch?? I just had my clutch replaced but after driving in heavy traffic my car does not go into 1, 3 , 5 gears. Can someone please tell me if it's bad for my clutch. I have told my mechanic this but he says it's just trying to adopt to your driving style since its been reprogrammed after clutch replacement. Thank you
 

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GPS won't mess with your clutch engagement as far as I know. Was a full adaptation run after the install?
 

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Oh ok that's good. And Yeah he ran full adaptation. I dropped it off at mechanics again today. He said he'll double check everything and reprogamme it. Let's see what he says tom. It's really annoying in traffic after everything heats up 1st 3rd and 5th gear won't engage. And if I have to stop I can't get moving again cuz 1st gear won't engage. I have to wait for it to cool down. Thanks for the reply
 
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