I have a 2003 a4 quattro 1.8T automatic with a TRIANGLE warning light. The are NO OBD2 CODES. The PRND lights are normal and not on or flashing, but car barely moves forward at all... or not at all. Reverse works. I have been told to consider LIMP mode and that replacing the TCM (Trans ECU?) might resolve. I happen to have the same car in a 2000 model year as a parts car, so I have an extra ECU. I want to switch the and check tranny fluid level (I noticed fresh tranny fluid on the ground after I started the car after sitting for several months). Yes, checking fluid level is best to do first, but the car is in the street and checking/changing trans fluid is difficult.... must be done from underneath with car elevated. I have determined the trans type are the same or similar.

From the discussion, it sounds like ECU on my 2000 in under carpet, while it is located in engine compartment on my 2003.

anyone have comments on my situation? what does just the TRIANGLE warning light mean? Can I switch ECU's?

 

I just determined that my PRND lights are in fact solidly illuminated, so this must be limp mode. I like to know procedures to diagnose this as much as possible without scanners to check codes. Is there a procedure I can follow? Can I erase the codes without a scanner and see if it recurs?

 

you have moved across the B5 to B6 line with your 2000 to 2003. I don't think you can change ECUs. I have one of each and just starting with the O2 sensors they are different. I'm not at all an expert on differences, I just try to keep each one running. I yield the floor to those smarter. there is an electronic Convenience Module under the front driver's carpet on both, but that is not the ECU. both ECUs are under the hood. the 2000 ECU is easier to remove than the B6. Water kills the CCM (central convenience module) under the carpet in most cases. google the triangle. trans fluid level is a big deal with audis. good luck.

 

thank you. since this post, I did switch the TCM and it made a difference. Now it solidly goes into gear ready to drive. But i wont drive it because it has a serious tranny fluid leak and i dont trust the new TCM as you suggest. Now I need to rectify the tranny leak, which probably means pulling the tranny anyhow. I may pull both the 2000 tranny and the 2003 tranny. If they are physically the same, I will probably put the 2000 tranny in the 2003 along with the matching TCM. I fear repairing the tranny leak only to discover more serious issues with the tranny. I have never driven this car myself.