My car has the adaptive cruise and the forward alert system. There are no problems at all with the cruise but what does happen is that now and then the forward alert will turn itself on.

Whenever it does turn itself on, I can press the button and turn it off again without any problem.

In perusing the schematics and after some investigation I determined that it is a momentary switch that grounds an input to the control module while the button is depressed. This momentary grounding toggles the forward alert function on and off.

I thought it might be a bad switch making momentary contact over bumps and things, so I toggled it off and disconnected the switch.

No luck though, it still periodically comes on by itself even with the switch unplugged.

Anyone ever seen a problem like this? Ideas on what to check?

 

There's a Yellow/Blue wire runs from the Adaptive Speed Control Module, right at the front of the car, all the way back to the switch. If that's chaffing somewhere along its length and grounding, that would switch it on. Of course, it would also switch it off in the same way; does that ever happen?

 

In town it beeps incessantly at every traffic light, so except for the period where I had the switch disconnected, I can't say I've ever left it on long enough to know.

With the switch disconnected, it went most of a day and a number of restarts without going off.