2004 Cayenne S Brake Portioning Warning HELP!!

[athol]

Hey

I have an 04 Cayenne S (955) which is showing an odd fault. Please can anyone help?

The car drives fine, however I sporadically get a Brake Portioning warning come up in the centre display. It comes up and goes off in 2 or 3 seconds and have no noticeable affect on the way the car is driving. The fault happens in several situations so I haven't been able to find any pattern to it - happens when waiting in traffic, when driving, it doesn't seem to be when I press the brake so I don't think it's the message to the abs unit to apply the rear brake lights.

There is a fault which is common that brings this warning up, along with abs warnings and sometimes locks the car in gear that is related to water ingress into the wiring harness under the passenger (rhd) carpet. It is not this, we have checked and there is no water in there and the drains are all clear.

The main dealer reset the PSM unit and no faults where found as well.

Logically, there is a momentary miscommunication in the system which makes the car think there is a brake balance issue however, I don't think there is an actual issue. Trouble is, with no fault codes stored. we can't work out what the problem is!!

Any ideas or experience on this would be most welcome. Where the fault doesn't affect the drive, it could be the precursor to something more serious and so I've like to trace it down.

Cheers in advance!