Inspection Procedure 8

Defroster Function 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 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 rear window defogger connector F-16 for damage.

Q: Is rear window defogger connector F-16 in good condition?

YES: Go to Step 3.

NO: Repair or replace the connector. Refer to Harness Connector Inspection. Check that the rear window defogger system works normally.

STEP 3. Measure the voltage at rear window defogger connector F-16.




1. Disconnect rear window defogger connector F-16.
2. Turn the ignition switch to the "ON" position.
3. Turn the rear window defogger switch to the "ON" position.







4. Disconnect A/C-ECU connector C-16 and ground harness side terminal No.1.




5. 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-215 for damage.

Q: Is rear window defogger relay connector C-215 in good condition?

YES: Go to Step 5.

NO: Repair or replace the connector. Refer to Harness Connector Inspection. The rear window defogger system should work 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 rear window 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-215.




1. Disconnect rear window defogger relay connector C-215, 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-215 (terminal 5) and the fusible link (1).

NOTE: Also check junction block connector C-212 and intermediate connector C-126. If junction block connector C-212 or intermediate connector C-126 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-215 (terminal 5) and the fusible link (1) in good condition?

YES: It can be assumed that this malfunction is intermittent. Refer to How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions.

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-215.




1. Disconnect rear window defogger relay connector C-215, 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-215 (terminal 3) and ignition switch.

NOTE: Also check junction block connector C-211. If junction block connector C-211 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-215 (terminal 3) and ignition switch in good condition?

YES: It can be assumed that this malfunction is intermittent. Refer to How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions.

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-215 (terminal 4) and rear window defogger connector F-16 (terminal 1).

NOTE: Also check junction block connector C-217. If junction block connector C-217 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-215 (terminal 4) and rear window defogger connector F-16 (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-16 for damage.

Q: Is A/C-ECU connector C-16 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-215 (terminal 1) and A/C-ECU connector C-16 (terminal 1).

NOTE: Also check junction block connector C-214. If junction block connector C-214 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-215 (terminal 1) and A/C-ECU connector C-16 (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-06 for damage.

Q: Is rear window defogger connector F-06 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 the resistance at rear window defogger connector F-06 in order to check the ground circuit to the rear window defogger connector.




1. Disconnect rear window defogger connector F-06, and measure at the wiring harness side.




2. Measure the resistance value 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-06 (terminal 1) and ground.

Q: Is the wiring harness between rear window defogger connector F-06 (terminal 1) and ground in good condition?

YES: It can be assumed that this malfunction is intermittent. Refer to How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions.

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: It can be assumed that this malfunction is intermittent. Refer to How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions.

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