Vehicle = 2006 base Cayenne, 99K miles

We made it back from a 1600 mile trip, somehow, but the vehicle is now un-driveable.

Just about every idiot light has come on at one point or another during the trip.

We have fault codes from the DME, Xfer Case, A/C, and Electrical System that have popped up.

The last code states the Reduction Lock is stuck on, so we have parked the vehicle.

PSM (Fault Code on Dash Lit)
0285 Front Right Sensor
0290 Left Rear Sensor
2053 Transfer Box Control Module

DME (Engine Light On)
01, 23, 41, & F7

Transfer Case (ABS, PSM, & 4WD fault lights on)
2042 Servo Motor
2050 Transfer Box Switching Error
2039 Transfer Box Potentiometer

A/C (No driver Side A/C)
2100 Servo Footwell Flap
1809 Drive Motor Temp Valve Left
2101 Servo Motor Side Blower
0657 Servo Motor Central Vents
2193 Power Supply Blower Regulator
1336 CAN Comfort Off

Electrical System (Footwell Lights flash on and off and Electrical Overload idiot lamp lit)
0907 Load Management on Vehicle Electrical System
1520 Rain/Light Sensor
2197 Potentiometer for Footwell Lights

There could be more faults, but several systems could not be reached with the iCarScan tool (repeated communication errors)

I don't know where to go with this. It's like the car has been hit by a North Korean EMP bomb. It seems the whole electronics system is rapidly breaking down. Each time we start the car we seem to get new faults.

We've had the car for 10K miles (has 99K on it now) and things went pear shaped just before we left for a long trip.

Thankfully, it brought us home, but we're at wit's end at this point.

 

The communications errors are the clue.

Have you had the drivers or passengers footwells flooded? Sometimes it's not really noticeable if it's a slow flood and it never gets to the top of the carpeting (meaning there are several inches of water in the footwell - the carpeting is on top of about 2" of dense open-cell foam.)

Sounds like a bad case of the corroded footwell wires syndrome.

First thing to do it check the footwells for water. You might as well get down to Harbor Freight (believe it or not - you're in LUCK - they have a sale going on!) and get the 6 piece trim removal set. Plastic levers of various shapes used to pry trim off. Dealers will sell you the identical set in fancy packaging for about $50. It's about $6 from HF - sometimes free if you buy something else sale.

Then go to the car, use one of them to slip under the inside of the sill-plate with the pointy end facing you (out), and lever the other end back toward you. Do this about midway in the footwell. When the carpet starts to pull up - stick one of the other plastic tools under it so it can't snap back. Continue doing this until you can get your hand under the carpet.

Is it wet? Does it look like it has been wet? I imagine being on the Florida coast you've occasionally seen a bit of rain, and you might use the AC sometimes. Plugged drains (and there is a DIY in the DIY forum on cleaning them out - it's for a 958 but it's the same thing on a 955..) will cause flooding in the footwells.

Running through the footwells is the basic spinal cords of the vehicle. Each side has a big-*** bundle of wiring in it under the carpeting and foam. That's not bad in itself IF the wiring didn't have splices and joints in it - but it does. [Electricity + water + copper-wiring] = electrolysis = corroded connections = communications errors = multiple failures all at once.

Sounds like what's happening. There are a few threads addressing this problem and how to fix the wiring. It's not something you want the dealer to do since many techs will read all the codes and follow the PIWIS instructions for each item that involves replacing expensive parts - and it still won't work.

If you don't know how to solder wiring - ask around and find a ham-radio club in your area. One of the ham radio dudes will know how to do it - and do it well. You have to open every joint in the wiring in that area and examine it - any sign of corrosion cut the wiring back until you get clean wire, then splice, resolder, waterproof it.

I'd suggest looking for the threads about doing this. They're pretty detailed. If I stumble across one, I'll try to post it here. Or if someone knows of one - they could helpfully do that too.

Good luck! Glad you got the iCarScan working. Think of all the money it's going to save you!

 

^^^
Came in to suggest the wiring issue.

It is very easy to check and repair

 

I'll check the wires. Thanks for the Harbor Freight tip!

Are there factory splices in the harness that get corroded?

I am well versed in soldering. We manufacture avionics and use a lot of PTFE wire, so it is no problem.

Newark sells heat shrink tubing with an adhesive interior lining. Does anyone know if this will be waterproof?

 

Well, I'm not exactly sure I'd call the problem area a "splice."

I know enough about electrical stuff that I have a hard time calling "twist it together and wrap it with tape" a "splice."

Yes. Really. On a car that goes damned near 6 figures (or above it) new.

Thread:

https://rennlist.com/forums/porsche-...-flashing.html

I was going to suggest find some radio control car/aircraft guys. Deilinberger's suggestion of Ham Radio is a good one, but those guys aren't anywhere near as common as the R/C guys.
But you know how to solder, so it is a moot point.

 

I use the adhesive interior lined shrink tubing and terminals on most of my machines including flying contraptions and would recommend it for this fix.

They should be damn near waterproof, but I can not claim them to be as wiring itself is not waterproof. I have been amazed how much water can travel inside of a PTFE insulated wire between the strands due to capillary action when aided by large temperature swings and pressure changes due to ol' PV=nRT. Sounds impossible, but I can point you to several legitimate tests that display water traveling several feet into electric motors, etc. when things where thought to have been perfectly waterproofed!

Your best bet is making sure the wires you fix are at the top of the bundle when you put things back together so that they are as far from the waterline as possible if (read: when) it ingresses again.

 

Well, pulled the driver's side all apart and split the wiring harness loom.

First, there are no spliced wires in my harness at all!

Second, there is no evidence of water intrusion under the carpet.

Is it possible my base Cayenne does not have wire splices in the harness? There is no yellow tape at the pedal area. The forward section of the loom looks untouched and totally factory.

Now what?

I know I have had water intruding into the passenger side. The leak is fixed, but are there sensitive areas where water could cause electrical faults on the passenger side?

 

Marv - the majority of problems occur in the right side bundle (passenger's side) since that side has an additional leak source - the HVAC system drain. And I'm very surprised the left side had no junctions in it - from photos I've seen - Porsche has made connections there which weren't simply extending a wire - they were connecting two circuits together. I can't imagine that much difference between a base model and other models. The left side failures are often ignition lockout failures - and I don't remember you mentioning this.

Check the right side - that's probably where the problems are.

As far as the shrink wrap with a meltable liner - it's better than just shrink wrap.. and probably as good as you can get. Good to hear you know how to solder - so few people do.

 

Pulled the right side carpet back. I didn't see anything obvious.

Pulled open the plastic tunnel, but did not see any splices.

For that matter, there is nothing that suggests water has seeped under the carpet.

It could have, but there is no discoloration of the floor or the wire harness.

What about the fuse box on the right side of the dash?

Where do the common problems lie?

Is there a nice set of pictures of what to look for?

thanks!

 

Dug into the right side fuse box, pulled it out and the backside looks all clean and shiny.

Is it possible that two ABS sensors would fail and cause the 4-WD fault?

The check engine light comes on sometimes and sometimes not.

The Locked Transverse fault has not returned, but haven't driven it, either. Just turned it on to turn the car around.

 

Hi
Couldn't it be the battery?
Bad battery throws lots of codes
Easy to check to see if this is your problem
GL

 

Don't know. Thing cranks fine, but does that mean anything?

 

What's the date on the battery?
Can you check the voltage?

'Attach the negative voltmeter lead to the negative battery terminal. Check the voltmeter. If your battery is in good condition, the voltage should be between 12.4 and 12.7 volts. A reading lower than 12.4 volts means that your battery needs to be charged"
...or replaced I would think if having lots of random fault codes

 

New battery fixed this similar problem
http://www.planet-9.com/987-cayman-a...ease-help.html

 

12.25 VDC off

14.05 VDC engine idle.