Inspection Procedure 8

INSPECTION PROCEDURE 8: Defroster Function does not Operate.

Rear Window Defogger Circuit Part 1:

Rear Window Defogger Circuit Part 2:

CIRCUIT OPERATION
If the defogger does not operate when the 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 Tool:
- MB991223: Test Harness Set

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 10 "Malfunction of the A/C-ECU Power Supply system."

STEP 2. Check the heated door mirror.

Q: Does the heated door mirror operates normally?

YES: Go to Step 12.

NO: Go to Step 3.




STEP 3. Check the rear window defogger relay continuity.




Follow the table to check the rear window defogger relay for continuity.

Q: Is the rear window defogger relay continuity 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. Measure the voltage at rear window defogger relay connector C-206.




1. Disconnect rear window defogger relay connector C-206, 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 7.

NO: Go to Step 5.




STEP 5. Check rear window defogger relay connector C-206 for damage.

Q: Is rear window defogger relay connector C-206 in good condition?

YES: Go to Step 6.

NO: Repair or replace the connector. The rear window defogger system should work normally.







STEP 6. Check the wiring harness between rear window defogger relay connector C-206(terminal 5) and the battery.

NOTE: Also check junction block connector C-204 and intermediate connector C-116. If junction block connector C-204 and intermediate connector C-116 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-206(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 7. Measure the voltage at rear window defogger relay connector C-206.




1. Disconnect rear window defogger relay connector C-206, 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: Does the measured voltage correspond with this range?

YES: Go to Step 10.

NO: Go to Step 8.




STEP 8. Check rear window defogger relay connector C-206 for damage.

Q: Is rear window defogger relay connector C-206 in good condition?

YES: Go to Step 9.

NO: Repair or replace the connector. Check that the rear window defogger system works normally.




STEP 9. Check the wiring harness between rear window defogger relay connector C-206 (terminal 1) and ignition switch.

NOTE: Also check junction block connector C-203. If junction block connector C-203 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-206 (terminal 1) and ignition switch 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 rear window defogger relay connector C-206 and A/C-ECU connector C-06 for damage.

Q: Are rear window defogger relay connector C-206 and A/C-ECU connector C-06 in good condition?

YES: Go to Step 11.

NO: Repair or replace the connector. Check that the rear window defogger system works normally.







STEP 11. Check the wiring harness between rear window defogger relay connector C-206 (terminal 3) and A/C-ECU connector C-06 (terminal 1).

NOTE: Also check junction block connector C-205. If junction block connector C-205 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-206 (terminal 3) and A/C-ECU connector C-06 (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. Check that the rear window defogger system works normally.

STEP 12. 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: Go to Step 13.

NO: Repair the printed-heater line. Refer to Defogger in Windows and Glass/Heated Glass Element.

STEP 13. Measure at rear window defogger connector F-01 to check the ground circuit to the rear window defogger connector.




1. Disconnect rear window defogger connector F-01, 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 14.




STEP 14. Check rear window defogger connector F-01 for damage.

Q: Is rear window defogger connector F-01 in good condition?

YES: Go to Step 15.

NO: Repair or replace the connector. Check that the rear window defogger system works normally.




STEP 15. Check the wiring harness between rear window defogger connector F-01 (terminal 1) and ground.

Q: Is the wiring harness between rear window defogger connector F-01 (terminal 1) and ground in good condition?

YES: Check that the rear window defogger system works normally.

NO: Repair or replace the wiring harness. Check that the rear window defogger system works normally.







STEP 16. Check rear window defogger relay connector C-206 and rear window defogger connector F-04 for damage.

Q: Are rear window defogger relay connector C-206 and rear window defogger connector F-04 in good condition?

YES: Go to Step 17.

NO: Repair or replace the connector. Check that the rear window defogger system works normally.







STEP 17. Check the wiring harness between rear window defogger relay connector C-206 (terminal 4) and rear window defogger connector F-04 (terminal 1).

NOTE: Also check junction block connector C-209. If junction block connector C-209 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-206 (terminal 4) and rear window defogger connector F-01 (terminal 1) in good condition?

YES: Check that the rear window defogger system works normally.

NO: Repair or replace the wiring harness. Check that the rear window defogger system works normally.