VarioSpam

Hello everyone. I’ve had incident free motoring for a while until today when whilst driving a slew of error messages came up causing major loss of power and erratic braking. Any ideas appreciated but I will try to take it to a local indy ASAP. One question I have is whether it is likely to cause damage by attempting to drive it further.

Car:

• 2011 CTT 4.8
• Full service done just less than a year ago
• Transfer case was replaced 1y ago with the new type.

Symptoms:

• After driving for about 1 hour, it suffered loss of power when pulling away from lights, PSM warning light came on.
• Shortly afterwards, multiple errors came up including PSM, PASM, 4 WD “overloaded”, ABS, Chassis Ride Height, parking brake.
• The ABS would also come into effect sometimes when braking gently.
• Power transfer was erratic, sometimes it would barely move at all. Engine revs were smooth and gearbox was not shifting erratically, seems like the problem is the transfer box.
• I tried turning ignition off / on
• After a while it stopped being erratic, ABS and PSM lights remain on.
• Ride height is normal and electric parking brake is still operating correctly.
• Battery may be original but voltage level was showing 14.4v with ignition on, I had done a 1hr journey 2 h before the fault and trickle charged it 1 week ago.

It seems like this is an electrical fault because of multiple failures at once, and some seemingly spurious errors. I managed to limp home. Now wondering if anyone else has experienced similar and if it maybe OK to drive it 10 miles to the garage.

Here is the fault data from a generic fault code reader. These seem to be the relevant items, full data file is attached. I haven't checked any fuses. Would be interesting if anyone has the wiring diagram to see if there is a common point of failure for transfer box & ABS.

Thank you!

lml999

Potentially (ahem) a ten year old battery. I'd start there.

VarioSpam

Thanks, yes, it is "potentially". I've owned it 1 year, no record of it being replaced. The CTEK charger doesn't indicate a problem with it. I know its not great if it is original, but as these errors came up well into a drive rather than at startup I thought it would not be the cause of this.
Anyway, I guess I'll charge it with the CTEK and drive it to the indy garage.

VarioSpam

Ah, this thread from describes very similar symptoms to what I just got. The problem reported was 2 ABS sensors (BTW, that seems pretty crap to me that the ABS module doesn't detect the sensors to be faulty rather than randomly shutdown other critical functions on the car!). The day before this happened, I drove at 50-70MPH on roads with a fair bit of surface water, can remember the sound of it hitting the undercarriage. Maybe that didn't help.

I realise the battery could be the cause and is sensible to check, but I happen to have the system voltage always displayed on the instrument panel and I could see it didn't fluctuate during this time, staying above 14v.

@diamond-back , @Goody were you able to drive safely at low speed with this fault? I'm wondering if it is sensible to drive it to the garage. For the last few miles, when the ABS and PSM lights were on, low speed driving was stable - brakes were smoothly applied, car could pull away from halt.

wyowolf

I had a similar issue with my S. Battery tested good at Napa, showed 14V on dash, but once I replaced it everything worked again. I can't really say why. But it was a cheapish easy fix. This was 6 years old.

VarioSpam

Thanks, that's good to know and shows my reasoning was wrong

So likely to be the Battery or ABS sensors.

Farmer Michael

My experience here: https://rennlist.com/forums/cayenne-...l#post17740075

The short version I changed the battery but faults displayed were down to the faulty ABS sensor. Having said that at 10 years old the old battery was definitely passed its best.

VarioSpam

Great video, thanks for the response! The warning message sequence I saw was very similar if not the same as what you showed in the video. However, once the messages were dismissed they don't pop up again, I just have the ABS and PSM warning LEDs permanently lit. I don't see a warning about the sensor in the OBD, but I'm using a cheaper more generic code reader.

Oh, BTW, were you able to continue to drive it at all like this, or did it keep failing to pull away?

Farmer Michael

The car drove normally although I probably drove more cautiously assuming that I wasn't getting any help in the event of emergency manoeuvre being required.

VarioSpam

Confirmed it was due to one ABS sensor having failed. I was eventually able to drive it like this, turned PSM off just in case.