I currently have an 09' GL450 that a week or so ago the wipers started working intermittently and then stopped in a good rain storm on the highway. As you can imagine that was a very scary situation with my family in the car. Anyways, I have taken the vehicle to a local indy that works on European cars and he has had the vehicle for a couple days now. He just called and informed me that the issue is that it needs a new front SAM module. He mentioned he was surprised that we didn't get any SRS errors on the dash as that generally points quickly to a SAM module.

He did mention upon his tests, the error code that was showing up in the diagnostic was a stuck motor BUT he said that he was not seeing the wiper signal becoming activated when turning the knob on the wiper stalk. The rear wiper works fine and 100% of the time when requested, it is only the front wipers that do not work anymore on any of the settings. The fuses checked out and the cluster (wiper stalk) checked out he said.

I have a feeling that since I have the stalk working fine, and no SRS errors that it may NOT be the SAM module but a relay like you had an issue with. I'll certainly test the theory with someone in the passenger seat, I don't believe I've had someone in the passenger seat when trying this other than the initial time they stopped working. While that's probably shooting in the dark, it is worth a try.

I'm not looking forward to spending the $1,000 to replace the front SAM module right off the bat without bouncing this off of a few people online. Any thoughts?

Now that I have the vehicle back in my possession this afternoon, I'm going to check the fuses and relay (which I assume he already did but for my piece of mind). I found a fuse diagram but I can't seem to find a relay diagram anywhere online. Does anyone have that?

Thanks!
Andy