Inspection Procedure 9
INSPECTION PROCEDURE 9: Rear Window Defogger Does Not Operate.Rear Window Defogger Circuit (Part 1):
Rear Window Defogger Circuit (Part 2):
TECHNICAL DESCRIPTION (COMMENT)
If the 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: Harness Set
- MB992006: Extra Fine Probe
STEP 1. Check the A/C and outside/inside air selection damper control motor operation.
Q: Do the A/C and outside/inside air selection damper control motor work normally?
YES : Go to Step 2.
NO : Refer to Inspection procedure 2, "Malfunction of the A/C-ECU power supply system. Inspection Procedure 2
STEP 2. Check rear window defogger relay connector C-306 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Q: Is rear window defogger relay connector C-306 in good condition?
YES : Go to Step 3.
NO : Repair or replace the connector. Refer to general (electrical) Harness Connector Inspection. The rear window defogger system should work normally.
STEP 3. Check the rear window defogger relay continuity.
Follow the table below to check the rear window defogger relay for continuity.
Q: Is the rear window defogger relay in good condition?
YES : Go to Step 4.
NO : Replace the rear window defogger relay. The rear window defogger system should work normally.
STEP 4. Check rear window defogger connector F-20 and A/C control panel connector C-119 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Q: Are rear window defogger connector F-20 and A/C control panel connector C-119 in good condition?
YES : Go to Step 5.
NO : Repair or replace the connector. Refer to general (electrical) Harness Connector Inspection. The rear window defogger system should work normally.
STEP 5. Measure the voltage at rear window defogger connector F-20.
1. Disconnect rear window defogger connector F-20, and measure the voltage at the harness side.
2. Disconnect A/C-ECU connector C-119 and ground harness side terminal No.6.
3. Turn the ignition switch to the "ON" position.
4. Measure the voltage between rear window defogger connector F-20 terminal No.1 and ground.
- The measured value should be approximately 12 volts (battery positive voltage).
Q: Is the measured voltage approximately 12 volts?
YES : Go to Step 13.
NO : Go to Step 6.
STEP 6. Measure the voltage at rear window defogger relay connector C-306.
1. Disconnect rear window defogger relay connector C-306, and measure the voltage at the junction block side.
2. Measure the voltage between terminal 4 and ground.
- The measured value should be approximately 12 volts (battery positive voltage).
Q: Is the measured voltage approximately 12 volts?
YES : Go to Step 8.
NO : Go to Step 7.
STEP 7. Check the wiring harness between rear window defogger relay connector C-306 (terminal 4) and the fusible link (37).
NOTE: Also check intermediate connector C-35 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If intermediate connector C-35 is damaged, repair or replace the connector as described in general (electrical) Harness Connector Inspection.
Q: Is the wiring harness between rear window defogger relay connector C-306 (terminal 4) and the fusible link (37) 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-306.
1. Disconnect rear window defogger relay connector C-306, and measure the voltage at the junction block side.
2. Turn the ignition switch to the "ON" position.
3. Measure the voltage between terminal 1 and ground.
- The measured value should be approximately 12 volts (battery positive voltage).
Q: Is the measured voltage approximately 12 volts?
YES : Go to Step 11.
NO : Go to Step 9
STEP 9. Check ETACS-ECU connector C-301 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Q: Is ETACS-ECU connector C-301 in good condition?
YES : Go to Step 10.
NO : Repair or replace the connector. Refer to general (electrical) Harness Connector Inspection. Check that the rear window defogger system works normally.
STEP 10. Check the wiring harness between rear window defogger relay connector C-306 (terminal 1) and ETACS-ECU C-301 (terminal 12).
Q: Is the wiring harness between rear window defogger relay connector C-306 (terminal 1) and ETACS-ECU C-301 (terminal 12) 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 11. Check the wiring harness between rear window defogger relay connector C-306 (terminal 2) and A/C-ECU connector C-119 (terminal 6).
Q: Is the wiring harness between rear window defogger relay connector C-306 (terminal 2) and A/C-ECU connector C-119 (terminal 6) in good condition?
YES : Go to Step 12.
NO : Repair or replace the wiring harness. Refer to general (electrical) 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-306 (terminal 3) and rear window defogger connector F-20 (terminal 1).
NOTE: Also check intermediate connector C-32 and D-12 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If intermediate connector C-32 and D-12 is damaged, repair or replace the connector as described in general (electrical) Harness Connector Inspection.
Q: Is the wiring harness between rear window defogger relay connector C-306 (terminal 3) and rear window defogger connector F-20 (terminal 1) in good condition?
YES : It can be assumed that this malfunction is intermittent. Refer to general (Body and Chassis) How to Use Troubleshooting/Inspection Service Points -How to Cope with Intermittent Malfunctions.
NO : Repair or replace the wiring harness. Refer to general (electrical) Harness Connector Inspection. Check that the rear window defogger system works normally.
STEP 13. Check rear window defogger connector F-05 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Q: Is rear window defogger connector F-05 in good condition?
YES : Go to Step 14.
NO : Repair or replace the connector. Refer to general (electrical) Harness Connector Inspection. Check that the rear window defogger system works normally.
STEP 14. Measure the resistance at rear window defogger connector F-05.
1. Disconnect rear window defogger connector F-05, and measure at the wiring harness side.
2. Measure the resistance between terminal 1 and ground.
- The measured value should be 2 ohms 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-05 (terminal 1) and the ground.
Q: Is the wiring harness between rear window defogger connector F-05 (terminal 1) and the ground in good condition?
YES : Check that the rear window defogger system works normally.
NO : Repair or replace the wiring harness. Refer Refer to general (electrical) Harness Connector Inspection general (electrical). Check that the rear window defogger
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 : Replace the A/C-ECU. Check that the rear window defogger system works normally.
NO : Repair the rear window defogger.