Hi all,

Could do with some input on an issue with my 2004 Cayenne S. Had a minor but annoying problem where the 'auto hold' was dropping out at junctions and giving me no drive when I went pull away, then would suddenly re-engage a gear with a jerk if I added a bit of throttle.

Other issues: once or twice over a few months did not shift down from 5th to 2nd when coming to a halt. Last few weeks could not decide what gear it was in and just sat in D the whole while.

Valve body was chief suspect so I had that reconditioned here in the UK, fitted it and initially had all gears but really clunky shift. Reset adaptations on PIWIS and then no drive in fourth or higher. Suspected valve body so gearbox shop sent another one. Same problem.

I was getting really fed up so went to Porsche and ordered the new part. Now in and, while it is smoother than ever from 1-3, it will not drive above 3rd gear. It shows 4/5/6 on the dash display, no faults coming up but not engaging the gears. Just revs out like a clutch pedal is depressed. As road speed falls, it picks up D2/D3 and continues.

My workshop is experienced with Cayennes - owner has had three and currently runs an 06 Turbo S but this is a whole new thing on him. Latest suggestion is we change the transmission, but I think we are a long way from there at the minute and will keep digging first.

Any thoughts? Anything similar happened to anyone? I have had a good look through the forum and nothing similar that I can find. It was shifting up through the gears quite nicely before dropping the valve body. Maybe a tiny bit clunky on the 4th/5th but the solenoids all tested fine on the valve body recon test rig.

 

Found potential clue in Touareg training doc: solenoid N88 controls 4,5,6. Needs to be open but stays closed when no power. So checking feed to that when I get time to spend at workshop.

 

Check the valve body harness for fluid migration. Sometimes transmission fluid can migrate up the wires in the harness and damage the control unit.

 

Thanks, no sign of any fluid in the harness.

 

Automatic Transmissions are an art unlike building an engine. Find yourself an experienced transmission guy.

One time, I had a transmission that would continue to fail, replaced every iunternal part and we could not repair it. Purchase a new external case for a salvage yard, and all was good after that. Sometimes its not the obvious.

 

Thanks, got a good auto trans guy. But five laps of the block ago I had six gears, so I am going to try a few other things first. This is engine and transmission out to change it, and that is a big job on a Cayenne!

 

There was a TSB requirement to change the Transmission control unit when the valve body was replaced as well.
Could be worth taking a look.

 

Just to close this out: clutches burned on the 4-5-6 clutch pack. Had the transmission rebuilt: all good now but Cayenne bills never end...

 

how much did that set you back?

 

All in was about £2500 including a brand new valve body from Porsche.