SalvationArmyRanger

I hope someone out there can help me. I love my car, but I'm getting towards the end of my rope and the bottom of my bank account. Any advice or help is greatly appreciated.

Here is the story:
I went on a weekend trip and on the way back the buzzing door open sound was stuck on. My co-pilot cousin, who happens to work for the VW electronics research lab recommended jumping two wires on an unattached plug down by the passenger side door to get the buzzing to go off. Well, he was right. The sound went off, but so did the transmission. When he jumped the two wires it blew a fuse in the fuse box (the one that goes to the transmission etc.). I replaced the fuse, but then the car would not shift. I drove the next few hours at 55mph and around 5,000rpm's. Luckily I have a motorcycle and have been able to commute since January on that....but I'm getting a bit tired of being car-less and really want to get it fixed and over with.

I've listed the symptoms and the steps I've taken to try to fix it...but am not sure what to do next
Car Specs:
1993 Audi 100s
V6 Automatic
Front Wheel drive
268,000 miles

Symptoms:
1. Transmission does not shift (can shift into drive, reverse, park, neutral, but in drive it does not change gears)
2. The gear selector lights are all lit as if I were in all gears at the same time
3. Cruise control does not work

What I have tried to do:
After much searching on these forums I got a diagnostic. The results of which gave the code for a bad Multi-function transmission range switch (Neutral safety switch). Not being a mechanic, but confident I bought the $350 part and manual and attempted to replace the switch myself. (Note to anyone out there thinking of doing this yourself...it is a pain in the rear. Avoid it if you do not have much experience and all the proper tools...unless you are the type that likes creating sailing ships in a bottle) After replacing it, I was having the same transmission issue. I then took it to the mechanic and he couldn't get the VAG-COM to talk to the computer. Right about the same time I also started having problems starting up the car. It looks like I didn't put in the switch exactly right, and another $850 later my mechanic put it in. I'm now in $1,200 deep. Once the mechanic finished this he hooked it back up to the VAG-Com and still could not get it to talk to the car. I told him the scenario of how the whole issue happened and he said it sounds like the transmission control module, but he couldn't be sure since he couldn't get the computer to talk to it. He was more than willing for me to buy the $1600 replacement module, but I'm hoping that if this is the problem I can find it cheaper from a salvage yard. This is where I am at right now.

Any ideas on what I should do next?
Should I take the car somewhere else to see if they can communicate with the computer?
Is there any way I can get the transmission tested if I pull it out?
Can I get the computer tested if I pull it out?

Any and all help is greatly, greatly appreciated. Please help me save my beloved car.
-Michael
(San Francisco)

audiqv8

"2. The gear selector lights are all lit as if I were in all gears at the same time"

The car is in Limp mode. You are starting out in 3rd gear and will not shift. You are suppose to drive the car to your nearest Qualify Audi Dealer.

You mechanic is probably correct. The TCU (transmission control unit) is most likely fried (Thanks Cousin).

Maybe you could get that "cousin, who happens to work for the VW electronics research lab recommended jumping two wires on an unattached plug down by the passenger side door to get the buzzing to go off" to help pay for the new TCU.

This could also explain why Audi have all these electrical gremlins with a "cousin, who happens to work for the VW electronics research lab recommended jumping two wires".

Buy a used TCU from a junk yard and see if your problems goes away.

BTW you did check all the fuses and not just stop at the first blown one that you found?

MiB@100-2.3NF-91

Do you have a "Sport" button near the shift selector?

Quick ideas just out of head:

1. Check the transmission control unit connector.
Maybe it got loose or sometimes it gets corroded or flooded. I don't know TCU location in your C4, but in my 100/44 TCU sits under the dashboard, drivers side, besides the steering column, need to remove the shelf under the steering wheel and look deep inside. TCU look like big black box with big connector.

2. Try to find the same unit from scrap-yard, ask for return policy. Try it on to see that happen.

3. Now most important one. You should check the wirind between transmission and TCU. This stupid wiring was also driving me crazy. Wires usually gets broken or shorted at the metal body attachement clips. Wiring cable goes from driver's side firewall down and to the righ side of the transmission, it attached to the vehicle body by metal clips.

4. If you are planning to keep the car you should invest into VAG-COM, adapter and some laptop, so you can read the error codes by yourself and eventually save tons of cash.

Pretty much thats it for now.

SalvationArmyRanger

Thanks audiqv8,

I did check all the fuses. I will try to find the correct TCU at a salvage yard somewhere in the area, but I know it is not going to be easy, wish me luck.

Electrical Gremlins - is that what that new VW mascot is in their commercials? lol.

SalvationArmyRanger

Thanks MIB,

1. I'll check out the connector tonight. I'm pretty sure the TCU is in a compartment in the passenger seat, but I'll check the manual to verify.

2. I had the same idea regarding finding the TCU at a salvage yard, but I need to find one first, and then I need to convince them to give me a return policy.

3. Regarding the wiring between the TCU and transmission, am I just visually looking for broken or bare wires? Or should I be using a volt meter to check for a broken wire?

4. Vag-Com - I bought a cable off of ebay, but I'm having issues getting it to work with the included "free" software. The software can detect somehow that the cable is not the proprietary cable. Then again, if the my mechanic couldn't get a reading...

audiqv8

Try Chris at force5auto.com or Bruce at germanautoconnection.com

BTW is the door buzzer working?

MiB@100-2.3NF-91

3. Yep, pretty much you look for broken or bare wires or isolation, pay close attention to the wires undeneath the metal attachement clips. Also check the the multi-switch connector, sometimes pins could be rusted.

4. VAG-COM ver.311 should work, even unregistered version will show some error codes.

SalvationArmyRanger

Thanks,

No, the door buzzer is not working properly, it is still always on. Once I get the trani fixed I might just pull apart the dash and kill the buzzer all together. There's got to be a short somewhere, just not sure how to identify it.

For those of you who are reading this and might be trying the first website audiqv8 had a slight typo: force5auto.com