Let's fix an e36 Comfort Relay!
The comfort relay is an interesting thing the that clever German engineers in Bavaria came up with in order to drive us nuts (and drive us to the dealership for about a $200 repair). This little gizmo provides power to the sunroof and power windows, with which nearly all USA spec e36's come with. This is in addition to a fuse under the hood, and a circuit breaker (safety switch) in the dash. Guess the engineers wanted to make REAL sure that the windows only work under the right circumstances. Unfortunately this little device tends to fail over time, due to poor quality soldering.
So, wanna spend $200? Head for your local BMW dealer. Wanna spend $0 and get the same result? Read on..
Patient: 1993 325i
Symptom: Electric power windows and sunroof suddenly won't work. Driver window down, sunroof open. Everything else seems to work (lights, fan, radio, horn, etc). Wife is not pleased (it's her car).
Diagnosis: Failed Comfort Relay
Corrective Action: Repair the relay
Tools Required: Phillips screwdriver, 10mm socket on long extension, small flat-head screwdriver, bottle of beer, soldering iron. (This is a one-beer job).
Step 1: Remove the 3 Phillips screws holding the trim below the steering wheel (US Spec cars. I have no idea where this thing is located on RHD cars, sorry). Start by removing the trim covering one of the screws. I pried mine off with a small flat head screwdriver
Next, remove the 3 screws in the locations indicated (excuse the grubby finger, just got through working on the air conditioning on son's '89 325is):
With the 3 screws removed, pull forward (like towards you, towards the rear of the car) on the trim below the dash. Note that the side towards the drivers door has some plastic clips. They'll unsnap cleanly if you don't try to force them. See pic below.
Now the only thing holding the trim panel in is the 2 sets of wires plugged into the bell / buzzer module. Unplug these by squeezing the clips together. Don't worry about keeping track of which is which; one has 3 wires in it and the other has 4.
Now right under the trim panel you just took loose is a kick panel. This is basically a foam-filed thin aluminum thingie, I guess to protect your legs in an accident. It is secured by 3 recessed 10mm bolts as shown below:
Klang! Bet a metal thingie fell off when you removed the kick panel, didn't it? Not to worry, here's a picture of where it goes (you'll need this for re-assembly). It sits on top of the kick panel, and the bolt going through it is the one on the right side of the preceeding picture.
Having fun yet? Go ahead and open that beer now.
Aha, the mother lode. You're almost there. Now that the kick panel is removed, there's this swiveling rack that contains (in my case) 2 relays, a brown one and a blue one. The blue one is the comfort relay, that's the one we're after. Now for some unknown reason this rack containing the relays swivels, so it may not be pointing at you. If it's not, swivel it down so you can see the blue relay.
Now pop the relay out of the swiveling rack, and disconnect it from it's plug (just pull it out of the plug). Here's a picture of the relay still plugged into the socket, but removed from the rack.
Next, take your small flat head screwdriver and gently pry the edges of the blue cover away from the base. The blue cover is just a plastic shell; once you get it disengaged from the base the innards of the relay will fall out in your hand. Hopefully in one piece.
Here's what mine looked like with the cover off. You can see the broken solder joint (I circled it).
Whip out the trusty soldering iron, and re-solder the joint. Plug the relay back into it's socket and test the windows, they should be working now. Reassembly is the reverse of removal, and should take about 10 minutes.