Auto Trans: "no faults found or DTCs not supported by controller..."
05-20-2007, 01:51 PM
#1
Auto Trans: "no faults found or DTCs not supported by controller..."
Perhaps someone has seen this before. I STFA but didn't come up with much. Here's the situation:
1996 A6 Quattro with automatic transmission shifting problems. 02/96 production with the 88 pin connector to the 4A0 927 156 AL TCU. Car drives fine in Reverse or First, but in Drive or any other forward gear it won't more. If the car is in Drive and RPM's are gradually (or abruptly) increased to about 3300, the car will take off with a clunk. Once rolling, it seems fine unless you slow down again. If you try to start out in First and then drop in Drive when the car starts moving, the car will sometimes stall out when you go to drive. If you go to Reverse and back to Drive the car will also sometimes abruptly stall. Is it as if the car is in two gears at once.
Sometimes I can pull a 00753 code from the trans, but more often I get "no faults found or DTCs not supported by controller". I surmise that the 00753 is because the TCU knows the car is in Drive and that throttle is being applied, but when it doesn't see any wheel movement it assumes the wheel sensors are having an issue. Anyone know why I'm getting the cold shoulder form the TCU with the "no faults found or DTCs not supported by controller..." response?
I am using both my ancient ISO-COM and a friend's HEX-COM with 704.1 VAG-COM software. Same result either way. Auto trans fluid was changed at an indie when the problem first surfaced. I checked the fluid and the level is correct.
TIA
1996 A6 Quattro with automatic transmission shifting problems. 02/96 production with the 88 pin connector to the 4A0 927 156 AL TCU. Car drives fine in Reverse or First, but in Drive or any other forward gear it won't more. If the car is in Drive and RPM's are gradually (or abruptly) increased to about 3300, the car will take off with a clunk. Once rolling, it seems fine unless you slow down again. If you try to start out in First and then drop in Drive when the car starts moving, the car will sometimes stall out when you go to drive. If you go to Reverse and back to Drive the car will also sometimes abruptly stall. Is it as if the car is in two gears at once.
Sometimes I can pull a 00753 code from the trans, but more often I get "no faults found or DTCs not supported by controller". I surmise that the 00753 is because the TCU knows the car is in Drive and that throttle is being applied, but when it doesn't see any wheel movement it assumes the wheel sensors are having an issue. Anyone know why I'm getting the cold shoulder form the TCU with the "no faults found or DTCs not supported by controller..." response?
I am using both my ancient ISO-COM and a friend's HEX-COM with 704.1 VAG-COM software. Same result either way. Auto trans fluid was changed at an indie when the problem first surfaced. I checked the fluid and the level is correct.
TIA
05-20-2007, 05:59 PM
#2
AudiWorld Senior Member
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How did you check the trans fluid level?...
Why did you have the trans serviced? Was there an issue? Your problem sounds suspiciously like low fluid. Especially since it was recently serviced. Do you trust the indy?
To confirm the proper level, the car must be running, up to temperature (35-40 deg C) and level. Fluid must be pumped into the fill port on the right side of the trans pan (for 95-97 A6) until fluid starts running out the port.
Also, what kind of fluid was used? I use nothing but Pentosin ATF1 synthetic in my 96 & 97 A6s.
To confirm the proper level, the car must be running, up to temperature (35-40 deg C) and level. Fluid must be pumped into the fill port on the right side of the trans pan (for 95-97 A6) until fluid starts running out the port.
Also, what kind of fluid was used? I use nothing but Pentosin ATF1 synthetic in my 96 & 97 A6s.
05-20-2007, 06:09 PM
#3
This is my bro-in-law's car. Started doing this one day so he had the tranny serviced...
...at a well respected indie in the Boston area. There were no leaks prior to this issue (no obvious fluid loss). The filter and fluid were changed and there was no improvement. I checked the level myself today (I never assume anything and I trust no one) and the level was correct.
Agree that it does sound like low fluid...but it isn't. Thanks for the input!
Agree that it does sound like low fluid...but it isn't. Thanks for the input!
05-21-2007, 03:00 AM
#5
It's definitley a 000753 - something about an electrical failure from the wheel speed sensors...
I'm assuming that this is because the TCU sees the throttle open, the car in Drive, and the engine speed at 2-3000 RPM but gets no signal from the wheels that they are turning.
If I clear codes and try to drive the car, I get this fault almost immediately. Within another few minutes of trying to drive, I get the "no faults found or DTC's not supported..."
If I clear codes and try to drive the car, I get this fault almost immediately. Within another few minutes of trying to drive, I get the "no faults found or DTC's not supported..."
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05-21-2007, 04:06 PM
#8
AudiWorld Super User
WAG--Look at output speed sensor if it has one (on side of tranny)...
Both the sensor itself (tested w/ ohm meter) and the continuity of the wiring between it and the TCU. That sensor needs to function for the tranny to understand what is going on with the power flow as it heads toward the wheels.
05-21-2007, 07:10 PM
#10
AudiWorld Super User
Per Bentley, you may be right. Try...
It says code 00753 is associated with shift jolts. It points at wiring problems between TCM and ABS controller, wrong ABS controller installed, faulty ABS sensors at wheels, or if it's your very lucky day, Fuse 21 faulty.