bdoweidt

I have a 2004 Cayenne Turbo. Recently if the car isn't started within 24 hours, the battery is completely dead. I replaced the battery but the problem still occurs. The respected local mechanic put the car on a monitor overnight and couldn't find a short or any sort of hung sensor. This evening when I parked the car in a quiet place I can clearly hear a repetitive clicking noise from the rear tailgate that sounds somewhat but not exactly like the lock mechanism recycling every 2 seconds. It isn't the full cycle of the auto-pulldown feature but a metallic click. It actually sounds like it's lower in the bumper housing. This noise has been going for 30 minutes and persists even when the car is running. I'm confident that it's the cause of the dead battery and I'm hopeful that someone recognizes the symptoms. The car has 98K miles and has never had an accident. If anyone has come across this or may have some suggestions, I'd appreciate some direction. Thanks in advance.

dorumac

bdoweidt

I just went out to check and it is dry on both sides and in the tailgate. No signs of water or anything unusual.

deilenberger

Did you pry up the carpet in the wheelwells? You can use one of those plastic trim tools to wedge it out from under the plastic door sill covering. There is a very thick foam pad under the carpeting and it can be waterlogged and never show a thing at the top of the carpeting. The issues that's being looked for is corrosion of some big wiring harnesses that run right under the carpeting. They get soaked with water and there are several splices in them that corrode and cause all sorts of mischief. There are a number of posts on this topic, including one with photos in the DIY forum.

You have to narrow down where the clicking is coming from.. it might be the rear-hatch pulldown, it could be the gas cover lock. The pulldown has been known to do this sort of thing if something is stuck beneath the hinged stainless plate around the stationary lock bit in the hatch sill.

bdoweidt

Thank you for the direction. I was able to pry up the driver side carpet sufficient to feel for water near the door sill and I couldn't feel any moisture. Now that it's back in place I'll try the passenger side tomorrow. Since I've been driving the car regularly this week I haven't had any problems and I'm noticing that the noise goes away after about 45 minutes. Is there any way to check the health of the wiring harness using a voltmeter or anything more precise than looking for dampness? Is there anything that my Durametric might identify?

deilenberger

Unfortunately - the only real way is to pull up the carpet and disassemble the wiring harness (untape it - and especially examine each splice joint.) It may be dry now - but on a 2004 - I can bet'cha it's been wet in the past. Don't know of one that hasn't happened to. If it only happened a few times and didn't stay wet for too long it's probably not the issue, but if you're a 2nd or 3rd owner - you have no way of knowing that.

VulcanGrey

agree with deilenberger
I recently went through this with my 2004 CTT.
The carpet was not damp, the foam under the carpet was not damp, but the 6 splices near the dead pedal were in very slightly damp fabric hockey tape (from the factory, they all have this) and were corroded and cross-talking to each other and leaking voltage. Caused every problem in the book. The battery drained fast, the car was disabled, the dash lit up like a Christmas tree, every code in the book was set in the ECU, the steering wheel buttons barely worked.
I cleaned up that wiring and waterproofed it. And now everything is fine!

NelaK

I'd probably go through and pull fuses until it stops rather than opening everything up and guessing at whats wrong.

Once you identify what's causing the issue, then you can chase it down.

bdoweidt

NelaK and VulcanGrey, thanks for the further details. Pulling the fuses is more in line with my skillset so I'm going to try that first. Based on the picture from VulcanGrey, is this the only junction point that should be investigated or are there additional junctions throughout the floor?

deilenberger

That's one footwell - there are junctions in the other front footwell. Dunno about the rear footwells - haven't heard of anyone finding any, and they don't flood near as often.

VulcanGrey

You can pull each fuse at a time and put a multi-meter set to DC Amps on the terminals of each fuse to measure current drain. You should flip the door lock latches and the hood latch to put the car to sleep mode, first!
That way you can see which circuit is draining the most. You might be able to figure out if a relay is sticking, but it'll be hard to pinpoint current leakage to another wire or to the chassis, since the current will stop flowing if you remove that module. How will you tell if it's the module or the wiring splices? Many people have paid to replace countless computer modules or whole steering columns due to the wire corrosion that is easily fixed!
If it were me, and I have been through this, I would just get that wiring cleaned up and waterproofed first thing! It just needs to be done!

deilenberger

+1 - I have to agree. Any time we've seen oddball electrical stuff happening on a Cayenne that can't be tracked back to anything obvious - it's the damn splices. With a 2004 we can be about 99.999% certain those footwells have flooded - more than once. You can waste lots of time trying to track down a current draw - then replace a module - just to find the current draw is still there - it was in the wiring harness to begin with.

Just do it. It's documented well. If you don't know how to solder - find someone who does. Look for a ham-radio dude - most of them grew up with soldering irons in their tiny hands..

Wisconsin Joe

If you can't find a Ham radio enthusiast, find a Radio Control model hobbyist.

You can ask at a local hobby shop that sells them.

They know how to solder reasonably well.

VulcanGrey

or someone from a local Maker Space.

nodoors

Or just learn how to solder! LOL It is not hard.