BMW E46 Fanatics Forum banner

1 - 20 of 38 Posts

·
Registered
2001 330xi
Joined
·
667 Posts
Discussion Starter #1
Hi all,

On my way to track down the occasional P1531 error I get, I checked today the wiring going to the exhaust vanos solenoid (thermostat wire, exhaust camshaft pos sensor, vanos solenoid). All the wiring was in perfect condition and the volts at the camshaft position sensor were fine (12 v, 5v and 0v). Now, to the next culprits, the actual vanos solenoids.
The exhaust vanos solenoid (where I get the error for) showed a resistance of 12.4 ohm, while the intake vanos solenoid had 11.4 ohm. From what I read on the web the resistance should be around 11 ohms.

For now I switched the positons of the vanos solenoids (exhaust one to intake and vice versa), to see if the error migrates.

My question now is, what does the increased resistance in the exhaust vanos solenoid indicate, and could it lead to the open circuit error I get (occasionally)? I only saw other posts where the resistance was for instance 10 ohm instead of 11, and the poster said that a new solenoid fixed the problem. Would 1 ohm too much have the same effect than one ohm too few?

Sorry, electrical newb here.

Cheers,
fana
 

·
Registered
2001 330xi
Joined
·
667 Posts
Discussion Starter #3
So, I checked the wiring up until the power steering fluid reservoir where it then angles down and goes to that big plastic box under the intake that receives many different wires from multiple sensors etc. I assume the wiring goes from that box to the DME. Do you suggest that I open that box? It seems that in order to check the rest of the wiring, including that box, I have to open up that box and many wiring looms, so I shied away from that yesterday.

The P1531 wasn't coming up often, so I am still waiting if it comes back now that I swapped the solenoids.

fana
 

·
Here to serve y’all
2004 330Ci 85k miles
Joined
·
11,097 Posts
It’s fairly safe and easy to open the electronics box and pull the DME connectors off for careful inspection. If any of the sensors leaked oil, coolant, PS fluid, etc., there’s a good chance it wicked up the wiring harness all the way into the DME connectors. We see that happen regularly, so worth a look. At that point you can look up the oin assignments on newtis.info and check continuity to the solenoids while wiggling the wires.

Exhaust VANOS solenoid wiring diagram.
 

·
Registered
2004 325i automagic
Joined
·
2,031 Posts
So, I checked the wiring up until the power steering fluid reservoir where it then angles down and goes to that big plastic box under the intake that receives many different wires from multiple sensors etc. I assume the wiring goes from that box to the DME. Do you suggest that I open that box? It seems that in order to check the rest of the wiring, including that box, I have to open up that box and many wiring looms, so I shied away from that yesterday.

The P1531 wasn't coming up often, so I am still waiting if it comes back now that I swapped the solenoids.

fana
I think what BaliDawg is suggesting is to go to the DME and uplug the big #3 connector from DME itself and check for signs of oil or coolant contamination/corrosion. I had oil leak out of both the exhaust solenoid & the crank sensor, wick it's way up the wiring harness and collect at the dme. It caused some funny codes but no damage; if that happens with coolant though (from tstat or coolant temp sensor) it can corrode the dme and cause real problems.

You could then also lookup the pinout for your DME and measure the resistance of the wires between the vanos solenoid and the pin number at the DME connector to confirm wire is good along entire length
 

·
Registered
2004 325i automagic
Joined
·
2,031 Posts
My question now is, what does the increased resistance in the exhaust vanos solenoid indicate, and could it lead to the open circuit error I get (occasionally)? I only saw other posts where the resistance was for instance 10 ohm instead of 11, and the poster said that a new solenoid fixed the problem. Would 1 ohm too much have the same effect than one ohm too few?

Sorry, electrical newb here.

Cheers,
fana
Good question ... wish I knew the answer.
 

·
Registered
2001 330xi
Joined
·
667 Posts
Discussion Starter #7
Oh, okay, yes I got confused. So, I don't need to open up the plastic box under the intake (not DME), but instead I go directly to the DME box and look at the connectors. How do I find out which connectors and pins I have to test for the solenoids? I don't know how to decipher: VANOS valves
If somebody could give some newb advice here that would be awesome.
fana
 

·
Registered
2004 325i automagic
Joined
·
2,031 Posts
On that diagram, it looks like the VANOS inlet valve goes to pin 40 at dme with a green/blue (gn/bl) wire, while the VANOS outlet valve goes to pin 41 with a green/violet (gn/vi) wire.

Word of caution though, sometimes the wire colors are wrong on newtis wiring diagrams, and more rarely the pinouts can be wrong, so ultimately you need to confirm continuity with you multimeter.
 

·
Registered
2004 325i automagic
Joined
·
2,031 Posts
Thanks, looking more into how these diagrams work now. The wire should originate here, right? https://www.newtis.info/tisv2/a/en/e46-330xi-lim/VaiWKU8
at X6053!?

So, I'll check continuity and resistance from those pins to the output pins at the solenoid. Anything else?

fana
Well the x6053 connection is the other wire (aka pin 1 from each vanos solenoid) that goes to the fuse carrier A8680 (which is near the dme). Referring to the Vanos valve diagram you linked to in post #7 above it is the top half of the wiring diagram and does not directly connect to the DME. Having said that you could also pull those x6053 connectors and check for continuity, since it is half the circuit.

The bottom half of the wiring diagram in post #7 goes to the DME (A6000) itself, and at the DME you want to check the middle big #3 connector (X6003, black 52 pin) and specifically pins 40 & 41 for the two vanos solenoids. See: https://www.newtis.info/tisv2/a/en/e46-330xi-lim/VfcMLxU

Btw, the multimeter test leads might not fit to make contact and so you can gently insert a thin safety pin into the connector and then read continuity/resistance off of that. Make sure it is very thin so it does not spread apart the female connector leads and thereby actually creating a continuity problem. Use something thin enough to go in without resistance but that still makes good contact.

You can also disassemble the 52 pin connector by sliding out each of the two 26 pin rows; here is what it looked like when I had oil wicking up the wires to the DME:
 

·
Registered
2001 330xi
Joined
·
667 Posts
Discussion Starter #11
Thanks again. Can I spray areound with electrical contact cleaner in there, without problems?
fana
 

·
Registered
2004 325i automagic
Joined
·
2,031 Posts
Depends on what you find, but on the unplugged wiring harness connectors generally yes if needed. For the dme itself you want to remove it first so you are not flushing whatever contaminant further into the dme.
 

·
Registered
2001 330xi
Joined
·
667 Posts
Discussion Starter #14
Lever, thanks for all your help.

The values are as follow

Intake vanos connector pin - DME pin 40: 1.5 ohm and continuity says 001

Exhaust vanos connector pin - DME pin 41: 2.2 ohm and continuity also says 001.

Values of resistance seem to drop over time. I'm sure if I would measure in an hour, the resistance would be lower.

Are these values you would expect from a healthy connection?

Cheers,
fana
 

·
Registered
Joined
·
1,872 Posts
What does your meter read if you touch the leads directly?

That seems just a little bit high for 6' of wire...

t
 

·
Registered
2004 325i automagic
Joined
·
2,031 Posts
I think those values are ok, but maybe someone with more experience can chime in as I'm not an electrical expert. You are seeing the slightly higher ohm reading on the exhaust vanos solenoid,which is presenting the error code, but that wire is I think longer than the 9ne for the intake solenoid ... again not sure if that is significant or not but it is a small difference.

I think you have excluded any major wiring isdue so maybe best thing for now is to drive it and see if code reappears and whether it follows the solenoid you swapped over.

Fwiw, one thing I have noticed is that low ohm readings can be finicky on the budget multimeters I have, so I am not sure if the ohm readings at these levels are significant or not. (I would love to buy a nice Fluke someday but those are $$$ and I don't use them regularly).
 

·
Registered
2001 330xi
Joined
·
667 Posts
Discussion Starter #17 (Edited)
Scratch what I said before, new values here.

I just measured again, and got:

Leads themselves 1.0 ohm

Exhaust vanos - pin 41 : 1.1 ohm

Intake vanos - pin 40: 1.2 ohm

I'm using a very thin copper strand from a wire to put into the pin hole, the connection is a bit fiddly.

fana
 

·
Registered
2004 325i automagic
Joined
·
2,031 Posts
Again not an electrical expert, but the .1 & .2 ohms over the wires sounds good. My test leads ohm out at about that level (they settle down to .1 ohms after a second or so). You could try jiggling the wiring harness while taking the reading to see if that creates any issues, but you would need a more stable connection with the leads for that (alligator clip test wires and an appropriate sized needle/safety pin for the dme connector female leads or to backprobe the dme connector if possible). But it seems like the wiring is good. I guess just wait for the code to reappear and see if it moved with the solenoid.

That the test leads are at 1 ohm seems a bit high ...
 

·
Registered
Joined
·
119 Posts
Sure ..

You data is in error ... or your coils ar shorted. Allow me to "Essay" ... I hope it helps. I'm a working stiff , but want to give you enough info to help .. so (boss not around) here I go ..

Motor wire is fairly tightly controlled when its created (extruded then coated with enamel). Thats what solenoids are wound with. With knowledge the wire has never been overheated, a resistance measurement can determine its length fairly accurately.

In automotive .. we usually don't care about length directly. But we might care indirectly.

We ohm a coil hoping to catch one of 3 failure modes;

  • Open circuit (obvious)
  • Bare wire short to housing (from overheat or mechanical rubbing over time). (Overheat mode 1)
  • overheat failure (enamel insulation overheats, burns up & vaporizes ) mode 2
Overheat mode is the hardest to detect because it ALWAYS occurs in the CENTER of the solenoid or motor. A fan motor coil would still look perfect on the outside. You zero in on this with a meter .. but confirm it primarily with your NOSE.

I wish I knew .. but I don't know if there is a propensity for VANOS coils to overheat, but I doubt it.

Now .. .specifically speaking to your data:

Your test (but maybe not the Vanos) is FLAWED (100%for sure )

Leads = 1.0 ohm
It MUST read 0.0 so work on that first. Check the battery.Usually that's it on both analog and digitial meters. On analog meteres there is an zero knob on the front for this purpose. You short the leads then adjust the knob to 0.

Exhaust Vanos .. 1.1 ohm
At the moment 1.0 ohms is coming from your lead issue while [.1] is coming from the Vanos. I doubt that because that would mean the vanos is drawing about 60 -120 amps and that is a joke. about 10-12 ohms would be expected

2.) You must be compare the solenoid to an identical part and I don't know that Intake and exhaust are the same.

Your measurements:

Exhaust vanos - pin 41 : 1.1 ohm
Intake (similar)
Your measurement is way off .. because after subtracting your 1.0 ohm lead the coil is .1 ohm
That means 120 AMPS would flow through that coil. NO WAY .. 1-2 amp would be more expected.
10-12 ohms is about what i'd expect your coil to read.

I'll check my M54 vanos if you like . I have 2 x M54 .. (one of which Balidawg updated the DME for us remotely).

Best Regards,

-OurmanDan-
 
1 - 20 of 38 Posts
Top