how to test the rear defrost 1986 lesabre

Hi, I am new to the block and I need some help. I have a 1986 buick lesabre with a 3.8 liter engine. I need to how to test the rear window defrost. I can turn the switch on and it don't lite up like it use too. I replaced the breaker in the fuse panel with a 20 amp fuse just to see if it would lite up(it didn't). I checked the fuse to see if it were hot on both sides and it was. I am lost now and I don't know what to do next. I looked under the hood for a relay and didn't have any progress because I didn't see anything lable. I have owned this car for over five years and it was working not to long ago. I need any help that anyone can give me. Thanks Gold69: My e-mail address is [email protected]

The schematic shows two types on your car..
One with Manual A/C the other with electronic A/C.

I will explain the Manual one.. but the electronic wiring and voltages are the same to the electronic type defogger relay timer.

The fuses are noted as Fuse 7 and Circuit breaker 24 both are located on the fuse panel under the instrument panel.. the Circuit breaker will be a large can type in that position 24...

Your relay timer is noted to be below the A/C control panel (head) and behind the center of the dash.. The light is on when the relay timer is activated.

There is a Brown wire to the relay and a Orange/Black to the relay. They should each have voltage to them to operate the system. The brown wire is to the FUSE 7 and the ORANGE/BLACK goes back to the Circuit Breaker 24.

Check them for voltages first.

I suspect the Circuit breaker 24 has malfuncitoned or popped. But thats a guess.

Good Luck.