Originally Posted by Interceptor
I've got a 2001 K1200LT with the ABS II system. I discovered today that the brake lights don't come on with the front brake. I have a very good understanding of automotive electrical systems, I'm just looking for some details on this particular system so I don't have to tear the entire bike apart to find the problem. The brake lights work when the rear brake lever is pressed, that confirms that the relay and bulbs are good. I've checked the front switch, it closes when the lever is pulled. I've checked the wiring from the switch down to the two wire connector behind the headlight, all good. I'm getting 12v up to that connector (and through to the switch), so I suspect a wire between that connector and the relay is broken or disconnected somewhere. I just want someone to confirm that it's as simple as that, switch activates relay activates lights, and that the ABS module has nothing to do with it. I've read something about the ABS module controlling the light relay, but I think that only pertains to the newer integrated ABS models. If someone can point me to a schematic that would be great.
Correct that the brake switches of the Integral-ABS are controlled by ABS unit. Earlier ABSII, have regular (more simple) brake switches that should have continuity when brake (lever or pedal) are applied. Just be careful with 2001 year models as Canada and Europe got the Integral-ABS in 2001, BUT the USA got them starting in 2002 only. Based on the noise they do, you would know is you have Integral-ABS (with servos).
FOR ABSII ONLY:
Check attached picture for location of the connector AND location of brake light relay. To get to this relay you need to remove lots of stuff including the fuel-tank, Note that this relay is lower than all other relays - as it is in lower section of the electrical box.
As Input-Output to the Relay, the official BMW electrical diagram shows:
1) One GRAY-YELLOW wire (input from both brake switches)
2) One BROWN wire (normally ground in BMW bikes)
3) One RED-BLACK wire (power from FUSE #3)
4) One GRAY-YELLOW wire (Output to rear light unit)