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Starter not functioning with key, 91 Passat 16V auto

I repaired the starter interlock relay (1 bad solder joint), but the relay will still not function unless the Transmission Control Unit is unplugged. Terminals #1 and #7 at the Starter Interlock Relay lose ground when the ign is on.

It also seems like the trans is in limp mode and my VAG tool will not connect to the Digimat unit like it will with my 91 Passat. I wonder if the TCU is bad. I did find the OBD plugs hidden behind the center console. I checked the multifunction switch on the trans, but did not have the specs to determine if it was functioning perfectly or not. Also it seems like there is a water leak on the RS of the car. Could that have messed the TCU wiring up?

Is there any way to test the TCU without testing it with another one? I don't want to take mine out and risk damaging it in this Passat. Anyone have a good one for sale? I also saw what looked like an adjustment knob on the TCU..........what is that for?

TIA later, dave (on a learning curve)

----- Original Message -----

This car was towed to me today and I might even buy it if it is too messed up. It has nice wheels, sunroof and all the rest of the goodies! :-)

Yes the ign. switch was checked along with it's wiring to the fuse box. Yes the starter was checked. It works fine.

It appears that the starter interlock relay is either not working or another component on the car is causing this relay not to work. I have taken the cover off of the relay and I can press the contacts together and the starter operates.

Questions:

  1. Is there supposed to be a neutral safety switch (I have not seen one in the Bentley. Only references to the trans control module and ECU)

  1. I also noticed that the transmission is in limp mode, so could the TCM cause the starter not to function too? Hoping to kill two birds with one stone.

Oh and I have to search for the OBD plugs so I can plug my VAG tool into the modules. It is not under the trans selector cover like on my 91 Passat auto. Differences, differences, differences !!!! lol

TIA, dave

Reply to
dave AKA vwdoc1
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Does the back-up light work? I think it's on the same circuit from memory. Did you check the ignition switch red/black wire for starter voltage?

Reply to
Woodchuck

thanks Woodchuck! NO the backup lights don't work, but I will check that again with the TCM unplugged and plugged in. I might have to see if the sockets get power too. This car was sitting for a period of time.

YES the red/black wire has starter voltage. With the TCM unplugged the starter will operate normally in P but not in N.

Big learning curve for me! lol Guessing I would say the TCM is gone or maybe the wiring to it has water/corrosion damage. later, dave

Reply to
dave AKA vwdoc1

Just checked the back up lights; With TCM plugged in = NO backup lights and NO starter function With TCM unplugged = YES backup lights and YES starter function in P only

I am about to check the wiring to the TCM, but I still suspect that the TCM is also bad! :-(

095 927 731 Digimat I think that these were updated to 095 927 731BE, but I am not sure. thanks, dave

Reply to
dave

Dave,

no real help to offer but wanted to encourage you; you are giving good details, doing the knucklehead elimination stuff yourself and asking for help in climbing the curve.

Keep up the good work.

TBerk

Reply to
T

lol thanks for the encouragement TBerk! :-)

I think that all I need now is the transmission control module and I have found some used ones for this early 91 model. VW warehouse in WI has 63 new ones in stock at $808 list, so I am searching for the best price on a good used one now!

I know that there is a reason why Woodchuck asked if the backup lights were working. Must be a "simple" test to determine if the TCM is defective!

later, dave

Reply to
dave AKA vwdoc1

Reply to
Woodchuck

At the top going down this TCM reads:

1 9 BE 7 6 *

004 2392

E28 E69

HELLA MADE IN GERMANY VW (AUDI)

095 927 731 DIGIMAT 12v

GETRIEBE-STEUERGERAT 5DG 005 906-65

This is all I saw on this module. I believe it is for the 90- early 91 Passats. later, dave Reminder........ Before you criticize someone, you should walk a mile in their shoes. That way, when you criticize them, you are a mile away from them, and you have their shoes. Frieda Norris

Reply to
dave

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