Hi, could use some advice on troubleshooting a rear wiper problem on a 2004 MCS (late-2003 build). This is a car I bought new and sold to my son four years ago but he's sold it back to me. It's only got 67K miles.

The rear wiper is completely inop. My son owned the car when it went AWOL; he said it worked intermittently a couple times then quit completely. Front/rear washers and front wipers work fine.

I pulled the rear trim and removed the wiper motor assembly. It runs fine if I apply 12V to pin 3 (red green) and ground pin 1 (brown). (I"m happy about this as my early-build car can't use the currently available replacement motor without replacing everything including the wiper arm.) I removed the gearbox cover and everything looks great in there too - lots of grease, intact teeth, etc. I just never get power to pin 3 when I turn the rear wiper on. The F17/15A rear wiper motor fuse in the left A-pillar kick panel is good and has power to one side of the fuse when I turn the ignition on. When I turn the wiper on, a relay (I01142) on the back side of the fuse panel is supposed to close and power pin 3. (BTW, as I understand it, pin 2 is an extra ground controlled through the computer - having two grounds allows for one to be closed by the motor to complete a cycle and park.)

So.... I surmise the problem is either that the relay is bad or the stalk switch is bad. Or I've got some open in the wiring between the fuse block and the hatch. Since all the other switch functions on the stalk work properly, I'm less inclined to think I've got a wiper switch problem although you never know for sure

The Bentley I have says the rear wiper relay is "non replaceable". (Thanks BMW!) I'm guessing I have to remove some of the kick panel trim to get the fuse block out, turn the panel over and see what is going on with this relay. Anybody done this?

Any suggestions? Anybody else had to replace this relay?

- Mark

 

Don't everybody talk at once! ;-)

For posterity, here's the outcome: The problem was an open wire between the BC1 computer (in the passenger kick panel) and and the wiper relay (in the driver's kick panel). Since the open was buried in the harness, the shop I used ran a dedicated wire along the harness to bridge the open. Rear wiper is back and working fine. I was pleased that the problem was not the motor (which is expensive and would have required replacing the wiper arm as well). And it wasn't the "non replaceable" wiper relay which would have either required soldering on the left fuse panel or replacing the fuse panel all together.

SK Motorsport in Bellingham WA did the work. They're BMW/Mini specialists and did the work quickly, kept me in the loop with the repair, and the cost was reasonable (~$350). It's hard to find a shop that can troubleshoot and fix weird problems like this. Recommended.

- Mark