Tiptronic Problems Audi A4 B5 2.5 TDI

Hello there,
I've been having significant problems with my Tiptronic transmission for quite some time.
Audi A4 B5, 2.5 TDI, manufactured in 05/1999, engine code: AFB, gearbox code: EFR.

According to the diagnostic software (unfortunately, I don't have VCDS yet):


18152 - P1744 Tiptronic switch, detection (F189) - Short circuit to ground.
17090 - P0706: Gear shift sensor - implausible signal, 35-00.

The following attempts have already been made without success:
Transmission oil flush, multifunction switch replaced, transmission control unit replaced, and switch F189 replaced!

I honestly have no idea what else it could be!
Except for the fact that it's in limp mode, the transmission is running smoothly without any jerking!

Were new parts installed, or were used parts installed without proper inspection?

The multi-switch is a brand new part, while the control unit (STG) and the F189 are tested used parts!

... then, only the wiring and connectors remain as potential sources of error for the selector switch.

Best regards, Rainer.

I was afraid of that. So, tomorrow I'll need to jack up the Audi and check the connectors and wiring. While I'm at it, I'll also test the new multiplexer!
"Today, I checked the sensor blocks for the switch position, and there's absolutely nothing coming through. If I'm interpreting the wiring diagram from ELSA correctly, doesn't the transmission control unit receive this information from the multi-switch?"

Since the error can now only be electrical, I've started from scratch and gone through everything again.
Fuse checked, OK. Disassembled the connector from the multi-switch and initially checked the supply voltage with the ignition on; it was too low (0.03V) or not present at all.

On Monday, I'll be going to the workshop first, where they supposedly tested the multi-switch and then replaced it.
I doubt the multi-switch was defective, because if it's not receiving power, it can hardly send a signal to the control unit indicating which gear is engaged!

I will keep you updated on the progress!

The solution to the problem was that three cables leading to the multi-switch had been cut. The multi-switch has been repaired, and the timing belt will also be replaced. I will provide the timing belt kit, and the workshop will replace the timing belt at no cost to me, as compensation for the incorrectly replaced multi-switch.

Thank you for the feedback!

That's the way it should be .