2003 Rear window defogger not working
 

What I can confirm

1) Fuse and relay OK
2) Metered defogger grid - OK
3) There is continuity from fuse to relay socket

Where it gets weird

The output from the relay socket seems to go to ground and not just output on the black/red stripe back to the rear window

When i meter the supposed ground (for the coil of the relay) I get something like 125 ohms and not just straight to ground like other relay sockets I have checked.

I can't confirm that the button on the heater control panel does/ doesn't work.

Somewhere there is another circuit that turns off the defroster when the window is clear, though I am unsure where that may be.

Any one fix this problem?

So after finding that the fuse, relay and defogger grid were all in ok condition, I focused my efforts on the AC ECU, once I had all the plastic pieces off and down to the circuit board I simply pressed the switch with my finger and the defogger light lit up. The problem is how the outer button presses onto the switch on the PCB, if it doesn't touch just right it won't activate the switch. I used a small piece of mica with a little piece of tape to hold it in place and re-attached the outer buttons over top. After everything was assembled, the mica between the button and the switch made it much easier to operate the switch.

The switch is just like one you would find in your TV remote control.

Hope this can help someone out there!

Hi,

Im actually having the same issue. The light comes on and the click is made by the left side of my knee. You mentioned a tv like button you press. Do you have a pic of where it is. Im not electrically inclined so im pretty lost with your comment.

all the help is appreciated.

Terry