audifield1

sorry i can't honestly tell you that. Give it a whirl! I just got impatient and cut the damn thing.
I'm going to start a new thread called " TCM Q's"

trying to find out if a fried tcm will give us our symptoms.....
Bob....

Prospeeder

you have an aftermarket cd player intalled in the car? thats why the scan tool will not communicate. Unplug the radio and it should work. I see it all the time. Im not sure why all these stereo intall places put the K line wire to positive, if u find the kline at the radio harness just cut and tape it. do a simple search on google. Then check codes. if you get any Throttle body malfucntion or throttle sensor codes, its either the ECU or the Throttle body.

thekingofvtec

factory radio.

thekingofvtec

UPDATE:

I bought a new engine computer.

Pulled up the carpet and removed tcu box, to find NO water, computer looks brand new, and interior of box is spanking new... then i realize that there is a dirt ring around the outside of the box where water could have been in the past, but still computer looks brand new.

Moved it around a bit, shake and rattle some wires, and AHA its starts, and stays running, rough, but smooths out. So i drove it...

IT WONT SHIFT. and its sluggish up until about 20 mph, thinking its launching in 2nd or 3rd and stays there??? The indicator lights on the dash are all illuminated by a red background, "PRND4321".

So just for the hell of it, i put the old computer back in, will start but stalls, but seems the shift indicator lights working normally, no red background, just red letters "PRND4321"

So for some reason with the old computer, tcu or tranny seems to function fine, but with new one, tcu or tranny will not behave.

audifield1

Hi it.s bob, ( guy with the same issues),,,,,just to clarify
so u bought a new ecu?
new ecu works with old tcu but stuck in limp mode?
old ecu works with old ecu but with background lights?
mine has old ecu and old tcu and has illuminated background lights.

pulled off entire throttle body and air intake to see if anything was clogged and it was not. nothing really too dirty either.
did u ever pull out radio?

thekingofvtec

yes, i bought an ecu out of a wrecked A6. The old ecu would not allow the car to idle, the new one does, so i thought my problem was fixed. The old tcu is in the vehicle, and it stays in one gear, and crawls to about 30mph. The PRND4321 lights are surrounded by a red background, but with the old "malfunctioning" ecu, the lights show up as the normal red letters.

Im trying to figure out if the tcu is fried. If so, why would it not give me the same PRND4321 light issue with the old inoperable ecu...

and no never pulled out the radio, it does not work, and does not light up. So i should change the fuse?

audifield1

Yes there is a separate fuse for the radio in the "left of drivers door" fuse panel. I pulled out the radio and disconnected everything based on one guys response as to why the obd11 scanner did not connect and it did nothing to change that!
seems if you don't have codes than nobody can help you.
I found and ordered a used tcu and ecu from ebay. found both identical parts ( all numbers match down to the last few bar codes) for $120 shipped. I guess I'll have to invest in a ross vagcom too to reset the ecu and tcu to the car and see if I can finally pull codes off this POS. I have an audi scanner now that is not a ross and it does not have the capability to do much more than pull codes. I have never had a car with such constant and hard to diagnose problems like I've had with this !!! I should have the parts in a couple of days and will let you know my findings.....bob

Audiwerkmeister

OK guys, three things.

1. It is not necessary to cut the carpet (I cant believe that someone did). The proceedure is to unbolt the front seat and remove. Then remove the back seat. Then remove the plastic cover trim that covers the inner door sill and runs from front to back. It will then be possible to lift the carpet to inspect.

2. I think that the electrical problems being described here are caused by a broken wire on the electrical harness. I would suggest first looking at the Connector going to the ECU. Pull the electrical connector apart and see it you can spot a cable which is broken.

3. The failure to communicate, usuallly means one of the ECU's is fried (or has a broken wire) . So unplug all the the ECU's you can find, then try the diag again. Use a process of elimination. Oh don't forget to check out both of the auto box electrical connectors under the car. Near the drivers side axle.

Happy hunting!

audifield1

ok on it!!!!!! see my other responses to your answering my other posts!
Thanks!!!

audifield1

ok so put in the new tcu with old ecu = no change
put in new ecu with new tcu and car runs much better but isn't even close to being right. dash reads -79 degrees so now I'm sure I need the ross or vag to reprogram ecu and tcu to car right?
also just had one of the cats go as I can hear the crap banging around in there and when i tap on it it sounds like a piece of metal rolling around. all that revving up trying to figure things out must have broken some combs loose. will that affect the way it runs or just be an annoyance?