Inspection Procedure 7
Defroster does not Operate.Rear Window Defogger Circuit Part 1:
Rear Window Defogger Circuit Part 2:
TECHNICAL DESCRIPTION (COMMENT)
If the rear window defogger does not operate when the rear window defogger switch is turned on, the rear window defogger relay system may be defective.
TROUBLESHOOTING HINTS
- Malfunction of the A/C-ECU
- Malfunction of the rear window defogger relay
- Damaged harness wires or connectors
DIAGNOSIS
Required Special Tools:
- MB991223: Test Harness Set
STEP 1. Check the A/C and outside/inside air changeover damper control motor operation.
Q: Do the A/C and outside/inside air changeover damper control motor work normally?
YES : Go to Step 2.
NO : Refer to Inspection procedure 9 "Malfunction of the A/C-ECU Power Supply system."
STEP 2. Check rear window defogger connector F-03 for damage.
Q: Is rear window defogger connector F-03 in good condition?
YES : Go to Step 3.
NO : Repair or replace the connector. Refer to Harness Connector Inspection. The rear window defogger system should work normally.
STEP 3. Measure the voltage at rear window defogger connector F-03.
1. Disconnect rear window defogger connector F-03, and measure the voltage at the junction block side.
2. Turn the ignition switch to the "ON" position.
3. Turn the Defogger switch to the "ON" position.
4. Measure the voltage between terminal 1 and ground.
- The measured value should be approximately 12 volts (battery positive voltage).
Q: Does the measured voltage correspond with this range?
YES : Go to Step 13.
NO : Go to Step 4.
STEP 4. Check rear window defogger relay connector C-216 for damage.
Q: Is rear window defogger relay connector C-216 in good condition?
YES : Go to Step 5.
NO : Repair or replace the connector. Refer to Harness Connector Inspection. Check that the rear window defogger system works normally.
STEP 5. Check the rear window defogger relay continuity.
Follow the table to check the rear window defogger relay for continuity.
Q: Is the Defogger relay continuity in good condition?
YES : Go to Step 6.
NO : Replace the rear window defogger relay. The rear window defogger system should work normally.
STEP 6. Measure the voltage at rear window defogger relay connector C-216.
1. Disconnect rear window defogger relay connector C-216, and measure the voltage at the junction block side.
2. Measure the voltage between terminal 5 and ground.
- The measured value should be approximately 12 volts (battery positive voltage).
Q: Does the measured voltage correspond with this range?
YES : Go to Step 8.
NO : Go to Step 7.
STEP 7. Check the wiring harness between rear window defogger relay connector C-216 (terminal 5) and the battery.
NOTE: Also check junction block connector C-213 and intermediate connector C-121. If junction block connector C-216 or intermediate connector C-121 is damaged, repair or replace the connector as described in Harness Connector Inspection.
Q: Is the wiring harness between rear window defogger relay connector C-216 (terminal 5) and the battery in good condition?
YES : Check that the rear window defogger system works normally.
NO : Repair the wiring harness. Check that the rear window defogger system works normally.
STEP 8. Measure the voltage at rear window defogger relay connector C-216.
1. Disconnect rear window defogger relay connector C-216, and measure the voltage at the junction block side.
2. Turn the ignition switch to the "ON" position.
3. Measure the voltage between terminal 3 and ground.
- The measured value should be approximately 12 volts (battery positive voltage).
Q: Does the measured voltage correspond with this range?
YES : Go to Step 10.
NO : Go to Step 9.
STEP 9. Check the wiring harness between rear window defogger relay connector C-216 (terminal 3) and ignition switch (IG2).
NOTE: Also check junction block connector C-212. If junction block connector C-212 is damaged, repair or replace the connector as described in Harness Connector Inspection.
Q: Is the wiring harness between rear window defogger relay connector C-216 (terminal 3) and ignition switch (IG2) in good condition?
YES : Check that the rear window defogger system works normally.
NO : Repair the wiring harness. Check that the rear window defogger system works normally.
STEP 10. Check the wiring harness between rear window defogger relay connector C-216 (terminal 4) and rear window defogger connector F-03 (terminal 1).
NOTE: Also check junction block connector C-218 and intermediate connector F-01. If junction block connector C-218 or intermediate connector F-01 is damaged, repair or replace the connector as described in Harness Connector Inspection.
Q: Is the wiring harness between rear window defogger relay connector C-216 (terminal 4) and rear window defogger connector F-03 (terminal 1) in good condition?
YES : Go to Step 11.
NO : Repair or replace the wiring harness. Refer to Harness Connector Inspection. Check that the rear window defogger system works normally.
STEP 11. Check A/C-ECU connector C-05 for damage.
Q: Is A/C-ECU connector C-05 in good condition?
YES : Go to Step 12.
NO : Repair or replace the connector. Refer to Harness Connector Inspection. Check that the rear window defogger system works normally.
STEP 12. Check the wiring harness between rear window defogger relay connector C-216 (terminal 1) and A/C-ECU connector C-05 (terminal 1).
NOTE: Also check junction block connector C-215. If junction block connector C-215 is damaged, repair or replace the connector as described in Harness Connector Inspection.
Q: Is the wiring harness between rear window defogger relay connector C-216 (terminal 1) and A/C-ECU connector C-05 (terminal 1) in good condition?
YES : Replace the A/C-ECU. The rear window defogger should operate normally.
NO : Repair or replace the wiring harness. Refer to Harness Connector Inspection. Check that the rear window defogger system works normally.
STEP 13. Check rear window defogger connector F-19 for damage.
Q: Is rear window defogger connector F-19 in good condition?
YES : Go to Step 14.
NO : Repair or replace the connector. Refer to Harness Connector Inspection. Check that the rear window defogger system works normally.
STEP 14. Measure at rear window defogger connector F-19 in order to check the ground circuit to the rear window defogger connector.
1. Disconnect rear window defogger connector F-19, and measure at the wiring harness side.
2. Measure the resistance value between terminal 1 and ground.
- 2 ohm or less
Q: Does the measured resistance value correspond with this range?
YES : Go to Step 16.
NO : Go to Step 15.
STEP 15. Check the wiring harness between rear window defogger connector F-19 (terminal 1) and ground.
Q: Is the wiring harness between rear window defogger connector F-19 (terminal 1) and ground in good condition?
YES : Check that the rear window defogger system works normally.
NO : Repair or replace the wiring harness. Refer to Harness Connector Inspection. Check that the rear window defogger system works normally.
STEP 16. Check the rear window defogger.
1. Let the engine run at 2,000 r/min, and check the printed heater with the battery fully charged.
2. Turn on the rear window defogger switch, and use a voltmeter to measure the voltage in each printed heater at middle point A on the rear window glass.
- The value should be approximately 6 volts.
Q: Does the rear window defogger work normally?
YES : Check that the rear window defogger system works normally.
NO : Repair or replace the rear window defogger.