Component Tests and General Diagnostics
GRID WIRE TEST1. Using a bright lamp inside the vehicle, inspect the wire grid from the outside. A broken grid wire will appear as a brown spot.
2. Run the engine at idle. Set the heated back window switch to ON. The indicator light should come on.
3. Working inside the vehicle with a voltmeter contact the broad red-brown stripes of the back glass window positive lead to battery side and negative lead to ground side. The meter should read 10-13 volts. A lower voltage reading indicates a loose ground connection.
4. Contact a good ground point with the negative lead of the meter. The voltage reading should not change.
5. With the negative lead of the meter grounded, touch each grid line of the heated back window glass back window glass at its midpoint with the positive lead. A reading of approximately 6 volts indicates that the line is good. A reading of zero volts indicates that the line is broken between the midpoint and the B+ side of the grid line. A reading of 12 volts indicates that the circuit is broken between the midpoint of the grid line and ground.