Rear defrost switch

[JordanBbradley]

Hey dudes when I redid my interior I removed my working defrost switch and now I don't which terminals I should be plugging the wires into. Please advice. 

 

I know that brown is ground: should that be the center terminal on the switch? 

And 

 

which terminal does the blue/green wire plug into: 4 options, center terminal, S labeled one(picture right),  31 + labeled one(picture top) or the non labeled switch(picture left) ? 

[John76]

Does this switch light-up when the defrost is on?

If so, you should have three wires:  Blue/Green from fuse box (+12V), Brown to ground, and Black/Red to the load (defroster).

 

[JordanBbradley]

Hmmm, I did not that I know of when I received it, but that isn't to say it should not. So potentially I should hunt down a third wire red/black wire? 

[Mike Self]

You do know that the switch you pictured is from an E21 3 series; the original defroster switch on your car was a simple pull  knob on the instrument binnacle.  So someone (you or a PO) must have run a wire from the instrument light circuit to the switch so it would illuminate when the parking/headlights are turned on.

 

mike

[HBChris]

I thought rear window defroster switches light up when on.  What year is your 02?  Dash looks like square tail light.

 

edit:. Guess I'm wrong, it lights up in e3 and e9 though.

Edited January 15, 2017 by HBChris

[John76]

The function is the same for both switches. Pull the knob and it completes (closes) the circuit from the +12V fuse source to the + side of the defroster (- side of defroster is always grounded on the passenger side of the rear window).

If you ground terminal 31 (brown wire) on the switch, the light will illuminate when knob is pulled. The S terminal is for the Blue/Green wire. The Black/Red wire (it must be somewhere under your dash) is connected to the blank terminal. Not sure what the funny looking brown center tab is for?

Note: If the light is always on, simply switch the blue/green and the black/red wires.

BTW, the rear defroster switch for a "76-'77 530i is illuminated, and matches perfectly the other three knobs on your dash (Lights, Lighter, and Fog Lights). I use the illuminated 530i switch for my fog lights.

John

[JordanBbradley]

Thanks for all the helps guys, the switch lights up and everything seems to be working like it should. checking out the 530i switch as an option later.