JAGMAN1

I am continuing to troubleshoot this issue. Here's what I've found with durametric.

Currently the only code that is a standout is in the vehicle electrical system section. Code 576 terminal 15 implausible signal.

There are "no signal/no communication codes in several different modules. All codes clear out and are a result of the errors that occur at startup.

Can anyone point me in the right direction on what this code means?

Thanks again!

Cole

Just to be sure....and I know this is a silly question......but are you SURE.....you have a single battery Cayenne? The second battery is hidden pretty well under the rear floor where the spare tire goes.

The only reason I ask is because that battery would be responsible for running all the electrical systems in the car while the one under the drivers seat would be responsible for starting it.

So, if you really did have a dual battery car it would explain your symptoms perfectly. Car starts fine, systems get error because second battery is dead/dying, until the alternator gets a chance to catch up with it then all is fine.

ekstroemtj

Are you shure about this? I believe
The battery in the rear is for starting only and the one under the drivers seat is for running the cars electric systems.

Cole

This was the only thing I have handy. But the way the car is wired with the jumper posts coming into the main battery under the seat it would make sense to leave this as the main starting battery and wire the house functions to the rear battery. Every car(most German) I have seen with dual batteries have the "house" battery as the furthest from the engine itself. The shorter run of wires to the starter motor for the starting battery and the shorter run of wires for the "house" functions just makes sense for so many reasons.


Notice that this mentions starting with the auxiliary battery "in the luggage compartment"

bigbuzuki

TSB 2706 describes the operation of the dual battery setup.
There seems to be a difference if KESSY is fitted.
Here is an excerpt from the TSB.

"The Cayenne S and Cayenne Turbo vehicles are currently being delivered with an auxiliary battery. The auxiliary battery is used exclusively for starting the engine. A cutoff relay connects it to the vehicle electrical system when the engine is started and disconnects it when the engine is not running. The auxiliary battery is located in the spare-wheel well in the rear of the vehicle and is charged when the engine IS running.

Vehicles equipped with the Porsche Entry & Drive System (KESSY)
When the plastic "KESSY" key (Arrow in Figure 1) is used to start the vehicle, the battery underneath the driver's seat is utilized. When the main ignition key is used, the current from the auxiliary battery is used to start the engine."

JohnnyBahamas

Another important piece of information that I did not know. Thank you for this.

Water cooled alternators and aux. batteries in the back that aren't used when I use the keyless entry system.

Who knew?



Post script: I don't think I have an aux. battery in my turbo. Looks like all I got is an upside down BOSE cake mold bolted to the floor. Denied again.

Cole

I saw that bulletin a while back. The thing that doesn't seem to make sense about it is that you would have to add a bunch of wire and "rewire" the first battery to add the second one in that way.

It would be MUCH simpler and more efficient from an electrical standpoint to just add the rear battery to run the house functions.

Basically, there is time, expense and functional losses associated with doing it as the bulletin describes. Which isn't very "Porsche" in many ways. Almost like the technical writer that wrote the bulletin had it backwards.

I'd love to see the actual wiring diagrams if anyone has them to compare.

mcbit

Don't think that it makes much difference really as I believe under non Kessy operations the batteries are paralled during starting, so the battery under the seat does pretty much what it does in a single battery setup. The second battery is there to assist during startup at is just tagged on via a couple of relays.

Cole

That is they way they normally are in most cars, and should be, and probably is.

That is why it would be weird to change the normal front battery wiring and divert it to the back for normal start up. Using up more current on every start with the extra long run of wire.

It makes more sense in the wiring to "add on" the rear battery and simply plug the "house" functions into it VS. "rewiring" or "rerouting" the existing start system to now run off the rear battery and have so much more draw to do it.


EDIT, I should have put in my first post that I had the multiple system failure issue and it was cured by replacing the rear battery, not the front one. Which would lead me to believe that the system is reversed of the bulletin

None of which matters in the least if the OP does not in fact have a dual battery. I've also seen many people here post that they only have one and come to find out they actually have two. So just thought I would double check.

JAGMAN1

I have assumed I do not have a rear battery based on the following assumptions.

1). I have a Bose subwoofer under the collapsable spare tire.
2). I do not have the option code on the sticker in the trunk for the second battery.

Based on this info should I look beneath the Bose unit in the trunk?

Cole

If you have Bose AND a spare then you're right, no dual battery.

Just wanted to make sure since people sometimes miss it hidden under the Bose without the spare tire.

bigbuzuki

Here's a wiring diagram for you Cole.

JAGMAN1

Gents your help is much appreciated. Any thoughts on the OBD 576 code in the vehicle electrical system?

I've been using Durametric for years and am pretty familiar with the my CTT and what codes it's prone having. I have a few other codes, but am certain they are not related as they've been present since before this problem manifested itself. (footwell potentiometer, rain/light sensor, and a towbar code).