Weave

will do, I will update you on what they assess and the proposed value for repair. I appreciate the input and suggestions

hillpc

We've learned a lot from tozoM8 over the years.

Now why wouldn't the TCU put the car in limp mode? Seems like limp mode would be preferable to leaving somebody stranded on the side of the road with this failure.

Is there a list of conditions that need to be satisfied to put the trans in limp mode available somewhere?

tozoM8

Incorrect gear ratios
tc faults any wiring wiring related to trans
any solenoid/pressure regulator valve faults
input/output speed sensor faults
temp sensor fault
F125 switch fault
any OBD code from P0700 to P0800

hillpc

Those make sense. But if the problem description is correct, I'm not understanding something. How come the car can't move forward at all with the TCU hooked up, but it will drive like it's got a blown A clutch when the TCU is unplugged? Shouldn't it be able to drive in 5 and reverse regardless of the wire bundle being hooked up or not? The symptoms as described would seem to imply that if all forward movement is disabled, we could cut (or unplug) the wire bundle and then (maybe) drive it home in limp mode. Screwy, no?

Weave

Morning ... I agree with you. Rather odd the A8 drives well without being connected to TCM or TCU. After my search under the car I did not see any frayed, pinched or damaged wires to the TCM. Now it’s at trans repair shop and after connecting it the car is showing more codes. It’s seems there’s a programming situation according to them, I’m awaiting an update. I have shared each of your input w the shop to guide this endeavor quickly as I’d like to drive this A8. Sorry for the late update I will share once I am informed and thank you again for the directions and suggestions ... Weave

Weave

Here’s today’s latest from the trans shop ...

Weave

I appreciate all of your suggestions and input. I have since reclaimed the A8 from the transmission shop. They state that their transmission guru advised them to not R&R my car. They said they could not offer a warranty for their work so I was not charged for the 2 week review. The A8 now starts without the red block of "PRND432" and drives for a few miles before I hear a loud clunk. At this point the red block returns and my A8 drives back in safe mode. Once i turn off the car and re start, itll appear and goes through the same pattern. At this moment I cannot find a used matching trans nor do i have the extra $$ to R&R my OE trans to be revived. The trans shop also declined the repair since they couldnt find the parts available and they claim they consulted several ZF vendors for parts that dont exist.

Rather interesting endeavor but I will ship my trans soon to European Trans in GA to revive and refresh with new parts for $2,200. They warranty their work w new valve body, torque converter and etc

I am seeking a place in San Diego to perform this removal, If you can refer me to a shop that can assist me in the R&R I would appreciate it

Weave

Dr. A8

What exactly does "revive and refresh" mean. Are we talking full rebuild or only replacing a few parts? $2200 sounds reasonable but the labor to R&R will probably be that much again.

Weave

Morning Dr A8 ... yes my revive and refresh is ET will disassemble and reassemble w new components, parts, valve body, torque converter etc to make this a new trans. I have to ship my trans to GA. That’s why I was asking for a place to remove trans in SD. Any suggestions Dr A8?