Rear Window Defroster Wiring

[Dick Steinkamp]

I made a little drawing of the wiring on the rear window defroster switch when I disassembled the dash, but it doesn't work when I hooked it back up again.

1. Maybe it didn't work before I removed it?
2. Maybe it was wired incorrectly to begin with?
3. Maybe I made a mistake? (That has happened once before...the time I thought I was wrong but it turned out I was right )
4. Maybe the switch is broken?

I have three wires to the switch.
Brown = good ground
Green/Blue = good switched (key on) 12V through fuse #10
Black/Red = wire to left side of defroster grid (the ground wire on the right side of the grid is hooked up)

For starters, what is correct placement of the 3 wires?

 

[adawil2002]

31 - Brown = good ground
+ - Green/Blue = good switched (key on) 12V through fuse #10
S - Black/Red = wire to left side of defroster grid (the ground wire on the right side of the grid is hooked up)

 

[bavbob]

OMG, thanks for this. I had this ? on my punch list since 2015 for my Bavaria. The only BMW switch I know of that does not have an idiot proof connector.

 

[Dick Steinkamp]

Thanks, Andrew!

Unfortunately that's how it was wired when I took the dash apart and how I put it back. I was hoping for an easy fix.

In researching further, I think the switch is bad. It does not work like the 4 way flasher switch and I believe it should. It is like it is stuck in the "up" (off) position.
I found this old thread...

Defroster Switch Repair

The defroster switch in my CSi hadn't worked in years, stuck in the popped-out position. This is a common problem with both the defroster switch and the hazard switch. Realoem lists the switch as part number 61311353590. GetBMWParts.com shows it as available, $83.58 list, online price of $66.86...

e9coupe.com

It looks like new switches are available through the normal sources, but they are expensive (for a Bavaria owner ). Get wants $159

I'm going to try to disassemble the switch to see if it can be repaired.

As a back-up, does anyone have a working used one for sale?

 

[adawil2002]

The repair is easy yet when I've repaired them the tend to fail sooner. I'll send you one of my spares. PM your address via Conversation & I'll send it our tomorrow.

 

[Dick Steinkamp]

Well, Like Andrew says...the repair was relatively easy. Getting the switch apart is the hard part, but once inside, the way it is supposed to work is pretty obvious. I probably spent 1/2 hour on it total.

Andrew, thank you for the offer of the switch, but let's see if mine holds the repair. Someone else may need one of your spares more than me. I'd hate to have yours sitting in my inventory while someone else goes wanting for one. I did cycle mine many times to see if it would break again right away, but it is still working. The rear defogger will get little (if any) use in this car so I should be OK. If not, I know where to find you.