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2010 Cayenne Base - Control Module or CAN Bus Issue?
As there is a LOT of stuff about similar Cayenne problems on the forum PLEASE let me know if this thread should continue here (I doubt it) OR be continued on an existing thread (most likely). Here's the short story...
Owned 7 years with few issues. Car started repeatedly throwing multiple Key, Headlamp AND non-specific SYSTEM FAULT messages on dash last week. When non-specific fault shows up car does not shut off but AC and PCM shut down and recycle. Then the non-specific fault message (and AC/PCM recycle) keeps occurring every few minutes or so. Normal 'Gear Selected' display changes from D1, D2, etc. to a backlit D (even in Park!) but all gears are available and driving is normal.
Car can 'reset itself' after being turned off for a while and restarted but problem comes back after about 10+/- minutes of driving. I have a Durametric Pro, logs and photos of my water intrusion / ratty splice search on both driver and passenger footwells which have both come up negative so far.
Looking at where to go from here but I don't want to post a lot about where I have looked and what I have done until I know I'm in the right place / thread. My quick analysis is that I either have a bad Control Module screwing up ALL communications on the CAN Bus OR I have a wiring problem (intermittent short / intermittent open / bad splice) on the two-wire CAN Bus itself or on a Power/Ground circuit to one or more Control Modules. Various Control Modules show good at some times and bad the next and the mix is always changing. I don't think they ALL have suddenly gone bad hence my focus on the CAN Bus and it's traffic level.
Any suggestions on where this should continue?
Barry
P.S. It's been a while since I've been on, why does it say 'Instructor' above my Avatar? I'm not an 'Instructor'...
Last edited by Barry A. Waters; 05-17-2023 at 05:27 PM.
OK, With no current objections I will continue this issue on this thread. If it becomes a problem I'm sure it can always be moved. Here we go... There is a mass of information on this type of problem scattered around the site but two of the MOST important threads (as far as I've been able to find) are located here:
I would recommend that anyone suddenly experiencing issues with the CAN Bus and multiple Control Modules on first generation Cayennes read through both as there is a LOT of great information in them. That is what I did and it has helped tremendously.
This is the Left-Side Driver's floor under the carpet and in front of the Driver's Seat. All was dry (including the carpet foam) and no splices were found. I think I need to continue forward with the main bundle as it moves up the A-Pillar and into the area of the Dead Pedal/Left Foot-Rest on the carpet. That would be to the left in the photo and up.
The under-seat Battery Compartment on the Driver's side. This is a 3 year old properly spec'ed Interstate AGM that reads 12.54+/- with no load and 14.63+/- with the Cayenne running. I might remove it and have it load tested but don't think it's the problem at this point. The single Positive and two Negative connections are fine with good contact. The Negative connection is a short, thick cable that only runs from the battery to the floor connection in the photo. The floor connection was removed and inspected and it was fine.
This is a High Current Positive distribution Bus situated outboard of the battery. All looks nice and clean. Look at the Amperage Ratings on those fuses...
From what I have read the 433 Relay with the purple mount is a Starting Relay. I have also read that it provides power for the CAN Bus and its Control Modules. And HERE is the first strange thing I've run into... I cannot remove it to test it. I'm thinking a straight pull up is all that would be required but it's not budging. It seems like it's locked into its mount. Is there a secret to removing this Relay?
Since it appears to be a Relay that would be engaged whenever the car is running could this be the maintenance equivalent of the DME Relay on the older 911s and 944s where it was common practice to ALWAYS carry a spare and replace it first if a 'no start / no run' condition occurred? If it was 'chattering' when it warms up (on, off, on, off, on, off...) it could potentially NOT shut off the engine BUT create havoc with the CAN Bus and any Control Modules it might power, which is essentially what I am experiencing. Hmm...
That is it for now and covers where I have looked on the Left (Driver's) Side of the Cayenne so far. Tomorrow I will post stuff from the Right (Passenger) Side where some interesting things WERE discovered but (at this point) don't seem to be the issue.
Barry
Last edited by Barry A. Waters; 05-18-2023 at 08:50 PM.
This is the Left-Side Driver's floor under the carpet and in front of the Driver's Seat. All was dry (including the carpet foam) and no splices were found. I think I need to continue forward with the main bundle as it moves up the A-Pillar and into the area of the Dead Pedal/Left Foot-Rest on the carpet. That would be to the left in the photo and up.
Barry
Left (Driver's) Side Floor Pan Wiring Har
Barry you need to open up the cloth tape on the harness and follow up up towards the front of the car. There are splices in it, keep searching until you find them.
Barry you need to open up the cloth tape on the harness and follow up up towards the front of the car. There are splices in it, keep searching until you find them.
Picking back up with the Right (Passenger) Side of the Cayenne, there is another wiring bundle under the carper that runs up to the A-Pillar on that side. You can see the splice and the Green Arrow points to the location where I found a clump of reddish/brown material that looked like dirt but had a VERY uniform granule shape. I stumped as to what it was. This photo was taken after I cleaned it up but the next two photos show it well.
Barry
Right Side Wiring Bundle
Last edited by Barry A. Waters; 05-19-2023 at 04:26 PM.
The granules of the clump looked almost crystal like & very uniform. Whatever it was, it was sealed with the wires inside the bundles 'protection box' so it didn't just 'fall' in there. Weird BUT I found no degradation of the wiring after I cleaned it up. Damn, I had high hopes when I first spotted it...
Finally on the Right Side (for now) a closeup of the one splice I DID find. This looks like a really good, gas tight splice. Note how shiny the copper wire is and the sealant sticking out both ends of the tube. I'm thinking this is fine so next up is back to the Left (Driver's) Side to continue forward and up towards the A-Pillar there. It might be a week before I can get back BUT I'll be back!
Barry
Right Side Splice
Last edited by Barry A. Waters; 05-19-2023 at 04:24 PM.
OK, MAJOR Progress (I THINK and HOPE). First up is a post AND a Factory Service Bulletin from Porsche (aka ATI in Porsche-Speak) on the Splice Issue that my initial search missed:
I had been pre-consoling myself to not be too dismayed if I got into the wiring harness further and found nothing by keeping the 433 Relay under the Driver's Seat in mind as a possible culprit. That seems to have been a good move as you will see. Once I got everything opened up again and the Negative Battery Lead disconnected I first went to work on attempting to remove the 'stuck' 433 Relay. The Relay is in a Socket that is mounted to a 'surround' next to the Battery that is quite the 'flexible-flyer'. Any pressure (in or out) on the Relay just results in the surround flexing like it's gonna break. Not good.
I figured the best way was to get the Socket off of the surround so I could get at it and the Relay somewhat better. That was a bit of a chore as it locks into the surround with two lugs/pins. One pin is accessible (the Left one) but the other (Right) is almost totally obstructed because the Socket is mounted in the corner of the surround. An Awl Pick with a 90 Deg. Tip finally saved the day on the Right side. Note that BOTH pins must be released at the SAME time in order to release the Socket from the surround. Man, this could have been SO MUCH simpler.... AARRRGGG... :-(
Barry
Last edited by Barry A. Waters; 05-27-2023 at 08:24 PM.
After a mini-celebration on getting the 433 Relay Socket removed from the 'surround' and THEN getting the 433 Relay itself removed from the Socket I removed the threshold and kick-panel trim to free up the foam-backed carpet so it could be folded out of the way. The Hood Release Handle just 'pops' off of its 'ball/socket' mount with direct pressure on it to the right side of the car. A Trim Tool works wonders here and with the kick-panel too.
Once the wiring bundle was exposed up to the A-Pillar / Dash interface it seemed to me that someone had been in there before. It lacked the Yellow Tape specified in the Porsche FSB (ATI) above BUT it did look pretty well done. So well done that I was a bit leery of cutting into it before I could source a new 433 Relay and see if IT was the true problem. That logic also got me into me cups sooner so it was a 'win-win' all around.
Barry
Last edited by Barry A. Waters; 05-27-2023 at 08:33 PM.
While the Carpet and its backing Foam were DRY there was some fine water droplets on the 'new' plastic electrical tape. The Wiring Bundle DOES run inside of a bit of a spacious 'tunnel' in the Foam backing at this point with nothing really in contact with it other than the surrounding air. We had a drop in temps last night/this morning that is somewhat rare this time of year so I'm chalking it up to Condensation for now.
05-16-2023, 07:50 PM
2010 Cayenne Base - Control Module or CAN Bus Issue?
