Ddbass
Member
Forum folks,
I have a very weird Transmission issue with my '13 Q7 TDI. Gearbox malfunction with multiple issues at once. I am very close to a diagnosis, but still far from a solution, so I'm hoping to hear from anyone who has experience with these issues.
I have had Gearbox malfunction issues for a while. First codes and symptoms sent me to the Trans Range Selector switch. The trans didn't know what the shifter was in. A replaced range selector switch partially fixed the issue. The old one was all corroded and encrusted. Further testing by a shop with VCDS showed the TCM to be bad. It too was corroded and encrusted. I got a new TCM and got a little more function, but now it wont go past 3rd gear and gets stuck there in limp mode, won't shift up or down. I did get reverse back and it doesn't get stuck in park anymore. After a Trans reset yesterday the CEL is on with code P2754 and P24CC (this car GULPS DEF). At some point I also had P0731, P2725, P0709, and P2755. I don't have VCDS but need to get it if I'm going to keep running these VAGs (also have 2012 Jetta TDI, manual transmission). Right now I am using a generic code reader and look up codes online.
So the P2754 code took me down the road of the Trans cooler control valve. And there I learn about the craziest automotive problem I have ever heard of. This valve can fail in a way that allows coolant to pass through to the wiring connection. Ok, so replace that valve and clean the connector wires. But no, it can get much worse! Coolant can actually migrate up the wiring sheath to the TCM, and fry it, which is what I believe has happened to mine. My original TCM was corroded and encrusted with green deposits from eroded copper pins. I believe this is also what took out my Trans range position switch which was similarly encrusted with deposits. The Range switch was the first thing we replaced, being careful to also clean all the connections on the plug. I thought it a weird coincidence that the TCM was also encrusted and wondered whether a prior owner, or my son had driven the car on the beach. Little did I know the fluid came through the wiring sheath! It seems insane to me that a coolant valve could fail in a way that could send fluid up the wiring sheath and destroy the TCM and maybe even the transmission!
I may not be completely right, but I'm betting this is the scenario. So my questions are:
1. Can I learn whether the wiring permanently damaged? Can it be replaced? repaired?
2, Is the Transmission itself permanently damaged from getting such random signals from a shorting TCM?
3. I read there is a TSB on this issue and would Audi fix it?
Here's a video on the matter.
Current status: After Trans reset procedure I can start off in D1 or S1 (still no M mode), I can drive around for hours (well i did 45 min through the neighborhood), starting off in D1 or S2, letting it shift to 2nd gear, and downshifting back to first when slow or on steep hill or coming to a stop. But as soon as I get fast enough for it to shift into 3rd then that's as far as it will go, the CEL light comes on, and I'm stuck in 3rd until I reset the trans.
There you have it, with the latest thinking and status. Any thoughts or experience out there with such issues? Would love to hear from you.
Thanks,
Dick D
Athens, GA
I have a very weird Transmission issue with my '13 Q7 TDI. Gearbox malfunction with multiple issues at once. I am very close to a diagnosis, but still far from a solution, so I'm hoping to hear from anyone who has experience with these issues.
I have had Gearbox malfunction issues for a while. First codes and symptoms sent me to the Trans Range Selector switch. The trans didn't know what the shifter was in. A replaced range selector switch partially fixed the issue. The old one was all corroded and encrusted. Further testing by a shop with VCDS showed the TCM to be bad. It too was corroded and encrusted. I got a new TCM and got a little more function, but now it wont go past 3rd gear and gets stuck there in limp mode, won't shift up or down. I did get reverse back and it doesn't get stuck in park anymore. After a Trans reset yesterday the CEL is on with code P2754 and P24CC (this car GULPS DEF). At some point I also had P0731, P2725, P0709, and P2755. I don't have VCDS but need to get it if I'm going to keep running these VAGs (also have 2012 Jetta TDI, manual transmission). Right now I am using a generic code reader and look up codes online.
So the P2754 code took me down the road of the Trans cooler control valve. And there I learn about the craziest automotive problem I have ever heard of. This valve can fail in a way that allows coolant to pass through to the wiring connection. Ok, so replace that valve and clean the connector wires. But no, it can get much worse! Coolant can actually migrate up the wiring sheath to the TCM, and fry it, which is what I believe has happened to mine. My original TCM was corroded and encrusted with green deposits from eroded copper pins. I believe this is also what took out my Trans range position switch which was similarly encrusted with deposits. The Range switch was the first thing we replaced, being careful to also clean all the connections on the plug. I thought it a weird coincidence that the TCM was also encrusted and wondered whether a prior owner, or my son had driven the car on the beach. Little did I know the fluid came through the wiring sheath! It seems insane to me that a coolant valve could fail in a way that could send fluid up the wiring sheath and destroy the TCM and maybe even the transmission!
I may not be completely right, but I'm betting this is the scenario. So my questions are:
1. Can I learn whether the wiring permanently damaged? Can it be replaced? repaired?
2, Is the Transmission itself permanently damaged from getting such random signals from a shorting TCM?
3. I read there is a TSB on this issue and would Audi fix it?
Here's a video on the matter.
Current status: After Trans reset procedure I can start off in D1 or S1 (still no M mode), I can drive around for hours (well i did 45 min through the neighborhood), starting off in D1 or S2, letting it shift to 2nd gear, and downshifting back to first when slow or on steep hill or coming to a stop. But as soon as I get fast enough for it to shift into 3rd then that's as far as it will go, the CEL light comes on, and I'm stuck in 3rd until I reset the trans.
There you have it, with the latest thinking and status. Any thoughts or experience out there with such issues? Would love to hear from you.
Thanks,
Dick D
Athens, GA
