Bought a 2004 Cayenne S with a Steering faulty error. Someone has obviously been messing with the car as once I had the Steering Faulty error taken care of and started the car, a whole bunch of other errors appeared. None of the steering wheel functions worked, it turned out that the electrical connector into the steering column was not pushed all the way in. That fixed some of the problems. But now I have still some weird communication issues between modules. I will read them again with the durametric, but I get a PSM error immediately upon starting, and also I get no indication of gear on the instrument display. On the selector LED readout, the D is always slightly lit, and fully lit when in D. But it stays dimly lit with the selector in all other positions. Car does not appear to be changing gear when going forward, however will select reverse, neutral and park. Manually changing gear does not work with the selector or with the steering wheel buttons. I replaced transmission control module; no change. Will check connections to the transmission, but anybody have any suggestions? Codes: DME module 1629, 0600. PSM module 2053, 1314, 1315. Kessy and electrical system, gateway 1299.

 

Sure - common. Your wiring under the front carpeting has corroded and is losing electrons. Could be either side or both sides. There is about 2" of foam rubber under the carpet that happily traps water around some big cables with lots of tiny wires in them, with junctions/joints in the cables. The junctions/joints corrode leaving the electrons nowhere to go.

The fix is to:
1. Find the leak(s)
2. Dry out under the carpeting
3. Fix the wiring

That's the short version - there are probably extended illustrated threads here about doing it - and I know there are some in the Cayenne 955/957 forum on rennlist.com

It's awfully common - and when bizarre electrical things start happening in a Cayenne, especially modules not talking to each other - it's about 99.9% sure that's the problem.

 

Agree with the above. There are 6 splices under the driver's dead pedal (under the carpet and foam). Those need to be cleaned up and fixed (Disconnect the battery, corroded sections of wiring cut away, soldered, and then covered in waterproof marine grade shrink tubing and silicone dielectric grease). I just had to do this after a steering faulty and many other codes. Clear all the codes with Durametric and then reset the steering angle sensor by turning the wheel 20deg each way and then drive straight a little bit.