In the last week when I first start the '04 CTT, I get just about every warning message there is (air suspension, PSM, brake proportioning, 4-wheel drive, transfer case, etc.). The PRND also lights up like every gear is selected. If I turn the car off and then restart all warnings go away. If I just leave it running, all but PSM clear. The car runs fine once everything clears out.

Any thoughts on this?

Thanks!

 

How's your battery? A failing battery produces all sorts of strange behavior in Cayennes. I have replaced the battery in my Cayenne 3 times.

 

+1 on the battery. For any faults which only occur at startup, the battery is the prime suspect.

 

Bad battery causes all kinds of wierd things to happen.

 

Thanks for the feedback, I too suspect a bad battery. I measured the voltage today and it was at 11.94 volts. That seems to be about 10% charged according to the chart I was looking at.

Any thoughts on which battery to use as a replacement?

 

I just replaced the battery in the CTT I sold to a colleague with a Bosch S5 110AH at $196.

 

Be sure to check the alternator ( charging voltage ) after installing a new battery.

BTW, this is a single battery P!g, not an early dual battery p!g, correct?

 

Correct this is a single battery CTT.

I ran it up on Durametric yesterday and it was showing 13.9 volts at idle. So I'm hoping the alternator is good. (103K miles)

 

UPDATE:
So I've replaced the battery (under seat) and the issues remain. To recap, here's what I'm experiencing:

Start the car (it starts right up), then a series of warnings appear, Air suspension, brake proportioning, AWD failure, PSM failure, and PRND is either blanked out or highlighted (as if all gears are currently selected). During this time I can't move it out of park.

After idling for about a minute, all the warnings clear and it is perfect. No issues whatsoever.

So far I've replaced the battery (single battery CTT) and it didn't change anything. Durametric is showing errors in all the modules that I've listed, with the most common denominator being a power interruption between the respective modules on the CAN bus.

 

Maybe there is a power drain somewhere--relay stuck open or some such. This would cause the low voltage on start-up even with a good battery and alternator.

 

That's a good thought. I'll start checking the battery voltage pre-start and make sure that it is where it should be. On a side note, the old batter was 5 years old and only showing 11.9 volts when I changed it so I don't feel too bad about putting a new one in.

 

I'm no expert, but you might be able to trouble shoot by checking the battery voltage while systematically removing fuses one at a time to identify the sub system with the power draw.

 

Not likely ...

 

you need to get a Durametric to read the error codes

 

Durametric shows no signal/communications errors in all of the modules that displayed a warning. There are no other obvious error codes.