PORSCHEMORCHE

Hello fellow Cayenners, I'll start from the beginning.I own a 2004 Cayenne Turbo 955, 137,000 miles and in pretty mint shape. I recently installed a new battery, I kept the battery charger on while I disconnected and connected a new one, so I wouldn't lose any codes so I thought. After I finished some strange things started happening. I started it up and immediately the load height warning came on and said take to dealer. I took it out for a test drive and the warning reset and all is well. I have "Entry and Drive" system and after a couple of days my plastic key wouldn't work and the key not recognized warning lit up. I had to start it with the key Fob that usually stays in my jacket pocket. The other thing not working is the door handle button to lock, the door handle upon pulling twice to unlock also went caput, the brake light warning came on but the lights work normally.
And for a scoop of ice cream on top my High beam need checking it says, even though they work fine. It bugs me as I like to keep everything working the ways it suppose to work. I was looking for reasons the headlights don't work and looking in the book at fuses I checked them and the fuse for headlights was fine. But I read in the fuse panel pages there was a fuse for additional High Beams in the passenger side panel, in the #8 position and to my amazement there was no fuse in that slot it called for a 20amp fuse and I say to myself "self what would be wrong in putting a 15 amp fuse in there and what do you know warning light gone and all works well with the high beams. Back to the "Entry and Drive" system the next day I tried the black key and boom it started up. This went on erratically for a couple of weeks. I took it to the dealer, my friends, put the computer to it and it said an antenna was cadavered, and I asked them to clear the codes and what do you know everything worked like it was suppose to, and I am happy for two days. Bingo the system quit working again. Yesterday I went out to try my plastic key and no it didn't recognize my key. I waved my fob down by my foot and close to the Kessy unit and bang it started with the plastic key.
Any help would be wonderful please I am under educated in car electronics so go easy on me.
Also, I lost a battery cover to my key Fob if anybody knows where to source one. By the way both my regular key Fob and my spare Fob with new batteries do not work.
Happy New Years

deilenberger

Keeping the battery charger on with the battery disconnected may have been a very expensive mistake.

A battery charger doesn't put out pure DC at 13V or so - when it's not connected to a battery. The battery works like a huge capacitor, damping out any voltage peaks and making the system see pure DC, not DC with ripple or some AC on top of it. Having no battery across the charger means unfiltered noisy voltage, perhaps at a voltage exceeding the expected 12.6-13.7V got into the system. The way that professionals do it is to put a 12V battery across the jumper points before disconnecting the old battery and bolting in the new one. I use a spare motorcycle battery I keep around and charged just for this sort of thing.

The bad news is - chances are you've damaged multiple electronic modules in the vehicle. Some might be sourced used from a wreck - some have to be coded specifically to the vehicle, and that's going to require a dealer. A clue this happened was the dead antenna - that wasn't a coincidence - something caused it to fail, and most likely was noisy voltage on the system due to the unfiltered battery charger.

Sorry - but that's how I see it - and I'm way too familiar with auto electronics..

Happy new year!

PORSCHEMORCHE

Does it matter if I had the charger set at 2 amps? In addition it was like 2-4 weeks after battery install that the entry drive system started going off as well as the beak e light warning. The headlight warning would trip three four minutes the before new battery install.
You did teach me a new lesson though. Thanks

PORSCHEMORCHE

Also how do I locate these antennas. Another thing that happened one morning it worked normal and I dropped my wife and she got out of the truck and bang the don’t recognize key warning came on. So I would start on the front passenger door if it’s got an antenna

VulcanGrey

Same thing happened to me after a battery replacement. Only my car was totally disabled with "Steering Faulty" and many other codes. The problem appears to be the poorly protected wiring splices under the drivers carpet, near the dead pedal.

Read this thread https://rennlist.com/forums/porsche-...in-park-3.html
After cleaning up the wiring and clearing the codes, the car has been fine since.

PORSCHEMORCHE

Thanks VulcanGrey , I remember reading your post a while back and I thank you for a reminder. I will look into it as my carpets and under carpet were caked with road salt so I know a lot of moisture has been down there. it took me a couple of hours to get the salt residue out of there and what do you supposed I used to do that? Yep, water and a brush to make it more damp. I will get at that when it warms up in Minneapolis its only -14 for tonight with a high today of -4. I do think i have some issues with that.
Do I ready the inspection just like I had to for battery replacement? Like making the seat tilt back or can I get at it with the seat all the back? It looks like in your post you have the seat tilted back like you are going to replace battery.
Thanks for the advice

VulcanGrey

yeah, tilt the seat back again, just like you did for the battery replacement, and then pull the carpet out from under the seat, and then up from under the sill, and pull up the thick foam under the dead pedal as well. Unwrap the tape up far enough to get to the 6 different splices.
I found one up higher than is shown in this photo.

PORSCHEMORCHE

thanks for the great photo it will help a bunch.

TomF

I hate to chime in here on the bad news front, but I completely agree with Don. Very likely you have fried several components of the electrical system. A full module by module test of the system is probably in order.

Best,
TomF

PORSCHEMORCHE

TomF excuse my inexperience but how do I test modules ? How do I locate each one and how many modules are there? Also what kind of test do I perform?
If its possible could you respond in laymen's terms? hope you can help guide me
Thanks

Wisconsin Joe

You hook up a diagnostic computer to the OBDII port under the dash. These cars are computer controlled and you need a computer to "talk" to it.

You will need something a bit more than the "code reader" that the parts stores (A/Z, O'Rs, Napa, ect) use.
I have a Durametric, and I think that will read those sorts of things.

A good Snap-On should, or take it to the dealer and have them plug in the "real" one. But that will cost you.

PORSCHEMORCHE

Thanks , I am confused as I did take it to the dealer and there was a couple of cadavered codes and they did clear them and everything worked as normal for a couple of days. I dropped my wife off at the Gym and while stopped with motor running she opened the door and bang the key not recognized came on and back to not working properly. So, the question is can these mods be a little not working but can become erratic ? I thought if something electrical fries its fried but this work- not work thing is what really confuses me. Thats why VulcanGuy gives me a little hope

Wisconsin Joe

I could be wrong, but generally, if an electronic component is "fried", it's dead.

Intermittent issues can usually be traced to bad connections in the wiring (again, generally, but not always).

I had the "water in the foam, soaked wiring harness, corrosion on those stupid @#%&* connections" issue myself.
It showed as a "didn't want to crank but would after a bit of fiddling" and ended up going to a "won't crank at all, no matter what" over a week or so.

v10rick

The number of modules is dependent on the number of options.
The modules are scattered...engine bay, under the dash, under the drivers seat and in the back of the vehicle.

Cayenne electrical system can be an electronic nightmare. If everything worked and now it doesn't or there is an intermittent fault its likely a connection.
There are hundreds of them...good luck.

Like Joe mentioned you need a scan tool like the Durametric or something similar to diagnose and reset the modules.

PORSCHEMORCHE

Got it thanks. Why should it be any different, its a Porsche:}