I have a problem with the rear defogger on my '99 Sunfire, it didn't works. The fuse is not blown, the light still comes on when I push on it, but nothing happen. In the positive wire of the grid there is some voltage, but when I plug it again in the connector the voltage drop to .......nothing. Somebody know someting about this trouble ??

I still have the same problem, too.

There is a printed cicrcuit board attached to the Rear Defogger switch which contains a timer and a relay.

Switching the rear defogger ON only energises the timer/relay solid state device and turns ON the on light. The timer circuit should energise the relay and switch power to the heater element.

I think the voltage you see with the rear element disconnected is from the ON lamp which is grounded by the rear element when connected.

A temporary jumper wire from terminal B to D on the printed circuit board will bypass the relay contacts and the rear defogger element should heat up.(This will power direct from the fuse to the element).I don't know if this will overheat if left this way-but probably?

A new, or junkyard switch assy that works, should fix it if the jumper test has the heater working.

Hope this helps


Alont