dpolson

Acquired a 2004 (I know, bad year) Cayenne TT with numerous undisclosed problems. Have a PST2 on the way to help diagnose. While I'm waiting for it to arrive, any thoughts on the following issues would be appreciated. 1) (see partial remedy below in next post) Stuck in low range. Switch operates, but low-range (square) LED flashes and "four-wheel-drive system fault" appears on dash. Does the failure-prone motor that activates the center differential lock also activate low-range, or is there a different actuator for that, perhaps in the transmission itself? Or is the controller box likely at fault, and if so, where is it physically located? 2) Both secondary air pumps are shot. Will replacing these likely also cure the catalytic convertor and O2 sensor codes that may be downstream effects of the shot air pumps? (P0491 and P0492 for the pumps, P0421 and P0431 for the cats, and P2187 and P2189 for the O2 sensor readings.) 3) Rear hatch glass window will not open. Is this more likely the microswitch on the wiper base on the glass, or the lock mechanism in the hatch? Will the PST2 tell me which? 4) Everything that has a push-to-open and push-to-close latching mechanism is stuck-- cup holders, storage drawers in front and rear consoles.. Any point in replacing these or will they just break again? Has design been improved? 5) When the O2 sensors wear out, will they throw a code indicating need for replacement? Car has 124,000 miles and unknown if they have been replaced. Looks like they are really hard to access. 6) Where can I find the best thread for describing how to replace the factory PCM/Bose unit? There is a CD stuck in it, the nav is non-functional anyway, and the system turns on and off at random. Might as well trash it and put in a Kenwood nav unit with rear-view camera! I realize I will have to bypass the MOST system and re-wire the car. Many thanks!

No response when actuating the rear window glass button. No blown fuses. Is the problem more likely the switch (I can hear it click) or the actuator in the latch itself? Will a PST2 tell me? Do I access this through the interior trim panel on the hatch?

Precisely.The low-range LED in the selector switch is flashing. Interestingly, it will not lock the longitudinal any more, either. Here is the exact sequence of events: 1) received the car, shipped up from Florida (and grossly mis-represented by the seller on eBay). It was supposed to have the off-road technology package. 2) To test for the presence of the package, I went to see if it had a rear differential lock by activating the controls. 3) Put the car in neutral and applied the footbrake, actuated the control switch forward (the switch was initially physically stuck, no doubt gummed up with spilled pop or the like) but it freed up and worked, electrically, going into low range with first actuation, then locking the center diff with the second actuation, and doing nothing more with the third actuation. No rear diff lock! (Seller simply lied. Car has no metal skid plates or variable-rate sway bars, either.) 4) Then, moving the lever back, it unlocked the center diff, then on second backward actuation it threw up the "fault 4-wheel drive system" icon and the led flashed a number of times. 5) If one repeatedly moves lever backward, nothing further happens at all, unless one restarts the car and tries it again. Then the error message and flashing led happens again, as in #4 above. My next step is probably to get a PST2 and attack it that way. But I would like to get some sense, before I go any further, of whether the problem is going to entail transmission removal (yikes) or simply replacement of the transmission control module. And in that regard, I don't know where that electronic module lives. Could someone please tell me? I have a Touareg shop manual on a Bentley CD, but I can't view it anymore because I upgraded all my computers to Windows 7 and it won't run on Windows 7!! (I need to get some XP-compatibility software and try that!) Thanks for help!

Yes and yes.

Just acquired a Cayenne Turbo and in testing out the systems, I put it into low range. Now it won't come out of low range. Switch appears to be working, as I get the message "must be in neutral and brake on" but even with those conditions met it will not come out of low range. How to fix? (I am 350 miles from the nearest dealer so I do all my own work.)

996 C4 viscous coupling center differential failure! I have two 2002 996 c4's with the same mileage (about 50,000) and live in Ouray, CO. One of the two does not pull with the front wheels, like yours, and thus is much more prone to getting stuck. I put both cars up on the lift to compare. Locking the transmission in gear (or park in the case of the tiptronic), I tried manually rotating the front wheels (both in the same direction) and on the car that pulls well, the wheels were somewhat difficult to turn whereas on the car that pulls badly, they turned quite easily. Conclusion: the viscous coupling on the latter car is shot and not providing any significant coupling. I called Prestige and discussed with the tech there and she said she has seen this before and had to replace the viscous coupling. They are going to do so on ours this week. I also read a VW discussion site which said these viscous couplings commonly wear out. Their opinion was that the VW synco viscous couplings (whcih are very similar to ours) have a life span of 60-90K miles. By the way, I use Blizzaks in the winter and other tires in the summer, and recommend the Blizzaks very highly for winter use. I can plow snow with the front spoiler going up a 20% grade! (If the viscous coupling is working, of course!) ;)

Help! I have a 2002 C4 cab with Litronic and the lights aim themselves very low (100' visibilty or so--very dangerous) about one out of four or five times that I drive the car. The other times, they aim up just fine. Both sides aim equally. It first happened when I bought the car (used, with 20,000 miles) and the battery was weak. Replacing the battery seemed to help bring the light aim up to approximately normal (though perhaps still just a tab bit low). Manual adjustment seemed to make no difference. So I began to think it might be voltage-related and I started watching the dashboard voltmeter. There may be a correlation, but since the voltage variations (between 13.4 and 13.8 volts or so) are small, it is difficult to say with certainty that there is a correlation. But it does seem that when the lights aim themselves low, the voltage is relatively low (closer to 13 than 14) and that when they aim up more normally, the voltage is closer to 14. Has anyone experienced this problem? What is the cuase and the solution? I drive a lot at night with deer on the road and need a solution ASAP. :) Thanks.