Window Defogger Grid Lines Test

For complete circuit diagrams, (Refer to Appropriate Wiring Information). To detect breaks in the rear glass heating grid lines, the following procedure is required:
1. Turn the ignition switch to the ON position. Turn the rear window defogger system ON. The rear window defogger switch LED indicator should light. If OK, go to Step 2. If not OK, (Refer to ELECTRICAL/HEATED GLASS/REAR WINDOW DEFOGGER RELAY - DIAGNOSIS AND TESTING).
2. Using a 12-volt DC voltmeter, contact the rear glass heating grid vertical bus bar on the right side of the vehicle with the negative lead. With the positive lead, contact the rear glass heating grid 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, repair the open rear window defogger relay output circuit to the rear window defogger relay as required.
3. With the positive voltmeter lead still contacting the rear glass heating grid vertical bus bar on the left side of the vehicle, move the negative lead of the voltmeter to a good body ground point. The voltage reading should not change. If OK, go to Step 4. If not OK, repair the ground circuit to ground as required.

Rear Window Glass Grid Test:

4. Connect the negative lead of the voltmeter to the right side bus bar and touch each grid line at midpoint C with the positive lead. A reading of approximately six volts indicates a line is good. A reading of zero volts indicates a break in the grid line between midpoint C and the left side rear glass heating grid bus bar. A reading of ten to fourteen volts indicates a break between midpoint C and the right side rear heating grid 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.