Had this problem a year ago. Initially very scared of what this might cost to put right. But this forum provided the answer.

Warning lights came on and ACC CMBS was disabled when I was idling. The car was four years old and a quick search here came up with sign of start of battery dying. So new battery and warning lights went off. Huge relief.

But it has started again and so despite stealership saying battery wasn't to blame, bought a new battery anyway, but this time the lights have stayed on. The diagnostic came up with codes for faulty ACC CMBS. They wanted the car in for two days of testing.I've not responded yet.

The lights go out and the ACC CMBS resumes when I reach normal travelling speed. I read that part of the ACC/CMBS system is a battery voltage sensor. I am presuming that there is a voltage drop when I slow down sufficient to trigger the warning lights.

I don't know anything about electrics. Is this something that could be caused by something simple like a bad earth or a dodgy battery lead? There was also the post the other day about a battery lead reset for electrical problems? I'd be grateful for any pointers. I love ACC CMBS it makes for very relaxing driving.

Thanks.

 

The complete reset calls for disconnecting the battery terminals, jumping the cables together, and turning the ignition to (II).

Check the terminal cables for loose connections, corrosion, or an overall bad cable. A low voltage could be the sign of a struggling alternator as well.

 

I've had this happen three times. The first time, the system failed and was replaced under warranty (would have been thousands otherwise). The second time, it was the battery. New battery, problem gone. Third time, it just went away. It's been over a year since and no problems. If I had to guess, I'd say something electrical as mentioined above rather than a system failure. When my system failed, all the lights came on and stayed on regardless of speed, restarting, etc.

LL