Relay is located under left side of dash near turnsignal flasher unit. It is the standard dark brown color is plastic, and has 5 pin connections. If you have a voltmeter or test lamp and want to troubleshoot it, the values are as follows. With the window switch off, terminals number 1,2,4,and 5 should be 0 volt. Terminal number 3 should be 12 volts. With the window switched on, terminals 1,2, and 3 should read 12 volts, and terminals 4 and 5 will read 0 volts. This is a transistorized relay with printed circuit, and is probably your problem. I would check the above mentioned voltages before replacing it however. You should also check for continuity with an ohmmeter, the orange oxide lines that go across the rear window, sometimes they get scratched and lose continuity. They are tin oxide, and get warm when current is applied to them.

Hope this is of some help.

Turbo240