Window Defogger Grid Lines Test

For circuit descriptions, refer to Wiring Diagrams. To detect breaks in the grid lines, the following procedure is required:
1. Turn the ignition switch to the ON position. Press the rear defogger switch once. The indicator lamp should light. If OK, go to Step 2. If not OK, refer to the Defogger Relay diagnosis in this group.
2. Using a voltmeter, connect the negative lead to a good body ground. Place the positive lead on the vertical bus bar on the left side of the vehicle. The voltmeter should read battery voltage. If OK, go to Step 3. If not OK, go to Rear Window Defogger Relay Test below.
3. With the negative lead of the voltmeter, contact the right side vertical bus bar. The voltage reading should not change. If OK, go to Step 4. If not OK, repair the circuit to ground as required.
4. Connect the negative lead of the voltmeter to the right side bus bar and touch each grid line at mid-point C with the positive lead. A reading of approximately 6 volts indicates a line is good. A reading of 0 volts indicates a break in the grid line between mid-point C and the left side bus bar. A reading of 10 - 14 volts indicates a break between midpoint C and the right side bus bar. Move the positive lead on the grid line towards the break and the voltage reading will change as soon as the break is crossed.