C7 S6 No Communication With TCM

[ForceFed4g63]

I recently changed the Transmission Temperature Sensor on my 2013 S6, and when I plugged the sensor back in and went to start the car it would not start. It flashed a TPMS Malfunction Light and Parking Brake Malfunction light. It also flashed a message saying to shift the car into neutral or park to start the car.

I then scanned it with VCDS, and I cannot get it to connect to the Transmission Module at all. I tried a few other modules and several others won't connect either. Below are the system warnings I'm getting.

At this point I am completely lost and have no clue what to do. I can't even limp it to a shop or dealership because the car won't start or allow it to shift into Neutral or anything. Does anybody have any ideas?


01-Engine -- Status: Malfunction 0010
02-Auto Trans -- Status: Cannot be reached 0100
03-ABS Brakes -- Status: Malfunction 0010
04-Steering Angle -- Status: OK 0000
05-Acc/Start Auth. -- Status: Malfunction 0010
08-Auto HVAC -- Status: Malfunction 0010
09-Cent. Elect. -- Status: Malfunction 0010
10-Park/Steer Assist -- Status: Malfunction 0010
15-Airbags -- Status: OK 0000
16-Steering wheel -- Status: OK 0000
17-Instruments -- Status: OK 0000
19-CAN Gateway -- Status: Malfunction 0010
22-AWD -- Status: Malfunction 0010
28-HVAC, Rear -- Status: Malfunction 0010
34-Level Control -- Status: Malfunction 0010
36-Seat Mem. Drvr -- Status: OK 0000
3B-Sensor Elect. -- Status: OK 0000
3C-Lane Change -- Status: Malfunction 0010
42-Door Elect, Driver -- Status: OK 0000
44-Steering Assist -- Status: OK 0000
46-Central Conv. -- Status: Malfunction 0010
47-Sound System -- Status: Malfunction 0010
52-Door Elect, Pass. -- Status: Malfunction 0010
53-Parking Brake -- Status: Malfunction 0010
55-Headlight Range -- Status: Malfunction 0010
56-Radio -- Status: OK 0000
5F-Information Electr. -- Status: OK 0000
62-Door, Rear Left -- Status: OK 0000
6C-Back-up Cam. -- Status: OK 0000
72-Door, Rear Right -- Status: OK 0000
8F-Pretens. Frt Left -- Status: OK 0000
90-Pretens. Frt Right -- Status: OK 0000
A9-Struct. Borne Sound -- Status: OK 0000
BA-Motor Mounts -- Status: Malfunction 0010

[gk1]

What sensor exactly did you replace? Was it Temperature Sensor 2 - G754 right in the like center tail of the trans?
I don't recall much other wiring in that area, but still I would re-check wiring.

[ForceFed4g63]

What sensor exactly did you replace? Was it Temperature Sensor 2 - G754 right in the like center tail of the trans?
I don't recall much other wiring in that area, but still I would re-check wiring.

Correct, it was the sensor that doubles as a drain plug. Literally didn't touch anything else under the car except for that sensor. Is it possible that a bad connection at that sensor can cause the TCM to go haywire?

[gk1]

Sadly anything is possible.
Are all the other malfunctions listed just refencing that they cannot communicate with the TCM or is there any more valuable info there?

[ForceFed4g63]

Sadly anything is possible.
Are all the other malfunctions listed just refencing that they cannot communicate with the TCM or is there any more valuable info there?

I couldn't find any relevant info when scanning the various modules unfortunately. Seems highly unlikely that many modules are all failing at once though.

[Alabama]

Seems highly unlikely that many modules are all failing at once though.

Voltage variation (e.g., gradually failing battery) may trigger multiple errors. Would a (false) high temp reading from the sensor cause this behavior?

[ForceFed4g63]

Voltage variation (e.g., gradually failing battery) may trigger multiple errors. Would a (false) high temp reading from the sensor cause this behavior?

I thought of the battery as well, but it's a newer battery (less than a year), and I kept the battery on a trickle charger for the few days it was on jack stands.

I decided to disconnect the battery for a day to see if that helps, I've heard it can help clear things. If that doesn't work I will get underneath the car again (huge pain as I don't have a lift), and start checking connections again.

[ForceFed4g63]

In case anyone was wondering or following along. I ended up taking out and examining the transmission connector/plug/harness, and there was coolant in there with some pretty serious corrosion. Seems to be a fairly common issue where the coolant solenoid/valve leaks. I ordered a new connector off ebay, and will be replacing all the connectors/plugs, and the valve as well. I'm just hoping the leak hasn't affected the TCM itself or the mechatronic unit. I guess we'll find out!