Communication problem

Leon Owner/Technician Arkansas Posted   Latest   Edited  
Updated
Network Communications
2009 Volkswagen Touareg V6 3.6L (BHK) 6-spd — WVGBE77L89D001188
Unable To Shift Out Of Park

Hello all, customer brings the vehicle in because “the brakes are locking up” (he says.) After some discussion we find out that the actual problem is that intermittently he cannot get the vehicle out of park. When the vehicle does not come out of park, you have no comms with any module on the vehicle but it will start and run. All of a sudden you'll have comms and the vehicle will come out of park and you will have communication codes for almost all the modules on the vehicle. I scoped the comm lines at the ECM and they both go from around 2.5V to around 1.5V, they mirror each other identically, appearing as if they're shorted together.. Anybody out there dealt with this problem in the past and what was the fix for it?? I am not afraid to test, I just don't want to waste the rest of my life testing when there's somebody out there that dealt with this problem or if there's a known cause for it. Thanks in advance for all professional polite responses!!

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James Technician
South Carolina
James
   

Hello. Check relay J329 for power supply when the problem exists, there is an issue with corroded wiring on that circuit under drivers side carpet

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Leon Owner/Technician
Arkansas
Leon
 

what does J329 power? or what would it be labeled as in my Mitchell1 wiring diagrams?

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Ronald Owner/Technician
New Jersey
Ronald
 

I had problems with the wiring under the drivers front carpet also for the same problem. Water gets in and corrodes the wires for the shifter

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Rolando Diagnostician
Texas
Rolando
 

Don't forget to check cowl drains, sunroof drains and A/C drains for blockage if corrosion found under the carpet. As well as water leaks

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Max Owner/Technician
Australia
Max
 

They rot the wiring under seats and both front carpets to bulk head if the have sun roofs

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Leon Owner/Technician
Arkansas
Leon Update
 

So, you guys are thinking i should concentrate on the shift interlock issue and not necessarily the communication issue, right?

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Dmitriy Analyst
Ontario
Dmitriy
 

CAN bus signal should NOT look like what you have in the Picoscope file. If you are sure you connected the leads correctly, and the signal looks bad when the issue happens, but looks good when the issue is not present, you have a partial CAN bus failure: modules on one branch of the network can talk, modules on the other one – cannot.

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