p38 cruise control problem

Is the Rev counter functioning ok?

First thing I'd check is the brake light switch. If the switch is set a bit "keen" it may well be operating due to the slight brake pedal movement when you hit a bump.

As part of it's normal operation the cc is designed to turn off as soon as you use the brakes.

cheers

Dave W.

With mine it turned out -- after many hours of diagnosis, luckily under warranty -- to be a poor connection in the plug connecting the ECU. One of the pins had pushed back in the plastic surround and was making intermittent contact.

Stephen

Does it fail after a while regardless of conditions, and a bump just makes it happen sooner? You could have a small split in the vacuum hose which is allowing air to leak in and stop the CC functioning. A bump might just open the split up a bit temporarily and break the vacuum totally.

Happened to mine a couple of weeks ago. Easy and cheap to fix. A bit of gaffer tape round the tubes and hey presto, back to cruising. (Thanks David, I'll be fitting the proper stuff next week.)

Nearside of engine compartment near the wing panel, towards bulkhead, three black rubber tubes leading into a conical black thingy. Pull them off and check.

HTH

yes fine.

Do you recall which plug and which pin?

Hmm - had one split next to the actuator, repaired it with tape, but maybe there is another. I'll investigate.

Thanks to all for the suggestions. Should keep me busy for a while, Ian.

I'm afraid not, because the dealer fixed it, not I. But I was told that one of the pins (or sockets) in the plug had pushed backwards in the plug as the plug was inserted so that it had not mated properly with the corresponding socket or pin. It took them 21 hours of labour to find it, having replaced other bits such as the connecting loom in the steering wheel and, surprisingly, the ECU itself first without success.

Good luck!

Stephen

Just a thought - I repaired mine with tape, and it sort-of half repaired the fault. Went back and repaired it again with LOTS of tape, and it was fine. I reckon it must be very sensitive to the vacuum.

I repaired mine (300TDi ES Disco) with some poly pipe from a well known DIY store, I dont have Vac probs but it still works when it wants. I've checked all the circuits except the earth, which goes via the alarm ECU!!! Thats my next target, beets me why it goes that way.

Peter