ABS not testing, False rear brake signal

[kr4mo]

I'm working on a 2005 R1200GS. The ABS light flashes at 4 hz all the time. The rear brake light is on all the time. The GS911 says the rear brake switch is activated, but the switch is unplugged. The heated grips are also heating up even though the switch is in the off position. Anyone else had any kind of issues like this?

[WayneC]

Dont know about the 1200 but BMW reuse the same heated grip 3 pin connector on other items on the 650GS so it would suggest a possible connector swap

[kr4mo]

Good point about swapped connectors. I will check that next

[kr4mo]

Turns out a new brake switch corrected the problem. Apparently the ZFE sees a disconnected switch as being a signal that the brake is pressed. Maybe this isn't just an off/on switch, but something more inside. Maybe a slight resistance. Does anyone know if this switch is held closed or held open with the brake is not pressed?

[WayneC]

Brake switches are usually normally open switches which close when brake is used

[kr4mo]

I agree with you about them being normally open,  but why would the ZFE see an unplugged switch as a signal that the brake was applied?  The old bad switch was also stuck in the open position.

[WayneC]

Good question, one I would not venture an answer on, it does seem rather odd

[mike d]

Brake switches are usually normally open switches which close when brake is used

Not in the case of BMW and ABS, they are normally closed, and then open when operated.

Mike

[WayneC]

This is one occasion I am pleased to be corrected, the 650GS is not set up that way on either of the ABS units used on the different models

[mike d]

Must admit I've not looked at the 650 range, only the 1100, 1150RT and 1200 models.

Mike