On the the climate control panel there is are 3 buttons, one says econ, the next looks like your windshield and the next one is square, this is the rear window defrost.
buick roadmaster 1992 rear axle does it have limited slip diff
rear wheel drive
located in back window with rear defog
passenger side on the bottom rear of the engine block
on the rear of the intake manifold on the drivers side
attached to the frame on the drivers side in front of the rear wheel
you probably have a bad ground in the rear taillight assembly common problem
the rear defog switch is located near the a/c dials on the front console and the washer fluid tank is located under the hood on the left side near the light
Component Location View. Drive Train LH rear of Transmission, near Driveshaft
On the frame rail in front of the rear wheels. Can't remember rt. or lft. side. Rick D.
Under the vehicle, passenger side, 2 feet in front of the rear tire, just inside the frame.
It should be on the passenger side 2 feet in front of the rear tire mounted toi the inside of the frame