Heated rear window switch ???

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steve

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I had a little melt down with my rear window defogger and now I'm trying to repair / track down the problem. (Smoke, burnt brown wire. Brown = ground?)

Anyway I have the switch out. And my question is, it is a 4 connector switch but when I look at the wiring diagram it only shows 3 wires going to the switch? I had 4 hooked up? Brown, black, green w blue and red w white. The 4th one why I smoked it maybe?

Anyway I'm under there repairing the brown and want to make sure I get it right after I fix the meltdown.
 
I don't think are 4 wires to be connected. This is a dirt simple circuit.

Brown, pin 31 is ground; only for internal light. It should have two brown wires (ground daisy chain to make electrical troubleshooting fun and link unrelated problems). :twisted:

The Green/Blue stripe wire is from the fuses (#8 )

The Black wire goes to the rear window.

When the switch is enabled (out) it connects the Green/Blue wire to the Black wire. The black wire is connected to the internal bulb which will turn on because it is ground with the Brown wire

The window is connected to ground on the passenger side and to the Black wire on the driver side.
 
Well it seems my ground wire is suspect right now. I have voltage to the green but no ground on the brown. Also it appears the brown has been tampered with because it is just a single wire and not daisy chained.

So I will try and follow this mystery wire and see whats been modified.
 
I am a bit concerned that the brown wire burned up. You better unscrew the cap and pop out the bulb; I've never seen a bulb short out (and be able to carry enough current to smoke an 18ga wire). I recently took apart one of these switches and basically when the button is pushed in all pins are isolated. When the button is out the 3 outside pins are all connected together and to the primary side of the bulb. The secondary side of the bulb goes to the center wire which is grounded. So, when putting is back together you should make sure of the following:

1. The brown ground wire should do the the center pin
2. The power input lead (heavy wire - green?) should go to any outer pin
3. The power output lead (to window - black?) should go to any outer pin

The bulb should light when the switch is "out" and the window should have power.
 
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