I have a 2004 Cayenne S with approx 165K miles. I've been battling the same electrical issue for about 2 years. My drivers side passenger door will continually unlock itself. If I lock the doors it will stop for some time but I imagine it will still actuate itself some time later as my battery will be completely drained after a couple days (just left me stranded at the airport last week). I just installed a new battery today thinking it was a weak battery and as soon as I put the new battery in the door lock started acting crazy again.

A little more background: I had a pretty bad sunroof seal leak that I finally got squared away and doesn't seem to be leaking anymore. The beginning of last summer I had gallons of water in my carpet so I dried it all up, cleaned my sunroof drains, and cleaned all electrical connections and grounds under the capet and still had a problem with the lock. I replaced the battery with a new one at this point and the lock issue disappeared for almost a year. A couple months ago it re-surfaced and sure enough the passenger side carpet was soaked again. Dried everything out and replaced the sunroof seal and now everything stays nice and dry but the lock issue won't go away. I also had an ABS/PSM light coming on occasionally which helped me decide to change the battery.

Any ideas? I have to leave my car for a few days again this week and really don't want to come back to a dead battery again.

This is one that will require diagnosing by process of elimination. Any other method is just guess work.

Connect an automotive ammeter in series with the battery. The resting current, with the key out of the ignition, should be less than .5A but this will depend on the number of options. If the current is that or less start by moving wire harnesses and connections to see if it spikes.

If the current is much higher to start with begin by pulling fuses until you see a drop in current. Then you can zero in the module at fault.

A Durametric analyzer could help isolate the fault.

The Cayenne electrical schematic is over 200 pdf pages. It is no surprise that electrical faults can be a nightmare to resolve. Especially when components have been exposed to water.

Thank you for the reply, I did check the current draw on the battery and it was pretty inconclusive. Once I finally figured out how to get the car to "rest" (doors locked and latched, but open in order to get to fuses), the issue was a bit intermittent and then disappeared all together and ended frustrated with a very low amperage draw on the battery (0.12 amps or something, don't remember)

So I left it at the airport for a week and in the mean time ordered a durametric (did not come back to a dead battery after all!). But I am still having an issue with that left rear door lock going off ALL the time unless I lock the car with the key fob. Happens when I'm driving and when I'm not, sooo irritating! Also, the passenger mirror occasionally has a mind of its own and will either point all the way up or all the way down when I get into the car.

Anyways, after clearing faults the ones below appear to remain active. So question is, where to go from here? Is there a computer for just the seat memory? Where is it? Or is it an issue with something in the seat itself? I assume this is what is causing my door lock problem? Same module?

From one who parks in the airport garage for a week or two, I feel your pain.

A resting current under .2a is good, would be nice if it remained there.

Based on the Durametric error try pulling Fuse 44 (left fuse box under dash). It powers the drivers seat memory module, also all the seat motors and the steering column adjust. It is hot all the time. Run another scan to see if the error is the same.

You may need to run without that fuse for awhile to determine if its contributing to a dead battery,while parked for a week.

I pulled fuse 44 on the LH side and did not get any of the error codes but it also did not recognize the module..

Since the battery is new and leaving it for a week with that fuse installed didn't kill the battery, it's going to be a long time before I know if this is the culprit for the drained battery. I would imagine it is since it's on the hot buss.

Will take a look at connections at the seat tomorrow for corrosion or any other discrepancy. What controls the seat memory and where can I locate that component? Will do the same there.

Sorry the wiring diagram does not provide the seat memory module physical location.

The seat adjusting switch signals the module which drives the motors.

This module communicates with other modules through the CAN buss.

The seat memory control unit is attached to the bottom of the driver's seat.

Well I removed the seat memory unit and cleaned all connections and no change. Still get a ton of fault codes. Again, the seat memory has been working fine although occasionally the passenger mirror will be pointed all the way up or down when I get into the car.

Still have the rear left door continuously unlocking itself..

One thing I noticed with the durametric is that I can run the 'short test all modules' and 'clear faults all modules' and the fault codes come up on the seat memory driver but if I go directly to the seat memory driver in the left column, the 'communications error' will come up as if it does t recognize that control module?

I also tried pulling each fuse individually in both the LH and RH fuse boxes as well as the one under the hood and the door lock still does its thing..

So the two questions still remain-- why does the door lock have a mind of it's own and why am I getting a ton of faults on the seat memory driver?

I guess the third is where do I go from here??? Any help is appreciated, this thing has been driving me crazy for far too long. I'm stumped.

Since Duramertic cannot communicate with the module that would explain the drivers seat related errors.
All the modules communicate via a CAN buss. Could one flaky module trigger an error in another?

I found no common hard wired connection between the seat memory module, the mirror and passenger door lock.
There is a drivers door control module that operates all the door locks and powers the drivers door mirror. It appears to be buried in the drivers door cavity.