Inspection Procedure 7

Defroster Function Does Not Operate.

Defogger Circuit Part 1:

TECHNICAL DESCRIPTION (COMMENT)
If the defogger does not operate when the defogger switch is turned on, the defogger relay system may be defective.

TROUBLESHOOTING HINTS
- Malfunction of the A/C-ECU
- Malfunction of the defogger relay
- The wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector.

DIAGNOSIS

Required Special Tools:
- 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 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. Measure the voltage at defogger connector F-16.




1. Disconnect defogger connector F-16, 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: Is the measured voltage approximately 12 V?

YES: Go to Step 14.

NO: Go to Step 3.

STEP 3. Check the defogger relay continuity.







Follow the table to check the defogger relay for continuity.
Q: Is the defogger relay in good condition?

YES: Go to Step 4.

NO: Replace the defogger relay. The defogger system should work normally.

STEP 4. Measure the voltage at defogger relay connector C-215.




1. Disconnect 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: Is the measured voltage approximately 12 V?

YES: Go to Step 7.

NO: Go to Step 5.

STEP 5. Check defogger relay connector C-215 for loose, corroded or damaged terminals, or terminals pushed back in the connector.




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

YES: Go to Step 6.

NO: Repair or replace the connector. Refer to Harness Connector Inspection. The defogger system should work normally.

STEP 6. Check the wiring harness between defogger relay connector C-215 (terminal 5) and the battery.









NOTE: Also check junction block connector C-212 and intermediate connector C-126 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If junction block connector C-212 and intermediate connector C-126 is damaged, repair or replace the connector as described in Harness Connector Inspection.

Q: Is the wiring harness between defogger relay connector C-215 (terminal 5) and the battery in good condition?

YES: Check that the defogger system works normally.

NO: Repair the wiring harness. Check that the defogger system works normally.

STEP 7. Measure the voltage at defogger relay connector C-215.




1. Disconnect 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 1 and ground. The measured value should be approximately 12 volts (battery positive voltage).

Q: Is the measured voltage approximately 12 V?

YES: Go to Step 10.

NO: Go to Step 8.

STEP 8. Check defogger relay connector C-215 for loose, corroded or damaged terminals, or terminals pushed back in the connector.




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

YES: Go to Step 9.

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

STEP 9. Check the wiring harness between defogger relay connector C-215 (terminal 1) and ignition switch (IG2).






NOTE: Also check junction block connector C-211 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. 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 defogger relay connector C-215 (terminal 1) and ignition switch (IG2) in good condition?

YES: Check that the defogger system works normally.

NO: Repair the wiring harness. Check that the defogger system works normally.

STEP 10. Check defogger relay connector C-215 and defogger connector F-16 for loose, corroded or damaged terminals, or terminals pushed back in the connector.







Q: Are defogger relay connector C-215 and defogger connector F-16 in good condition?

YES: Go to Step 11.

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

STEP 11. Check the wiring harness between defogger relay connector C-215 (terminal 4) and defogger connector F-16 (terminal 1).









NOTE: Also check junction block connector C-217 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. 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 defogger relay connector C-215 (terminal 4) and defogger connector F-16 (terminal 1) in good condition?

YES: Go to Step 12.

NO: Repair or replace the wiring harness. Refer to Harness Connector Inspection. Check that the defogger system works normally.

STEP 12. Check defogger relay connector C-215 and A/C-ECU connector C-16 for loose, corroded or damaged terminals, or terminals pushed back in the connector.







Q: Are defogger relay connector C-215 and A/C-ECU connector C-16 in good condition?

YES: Go to Step 13.

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

STEP 13. Check the wiring harness between defogger relay connector C-215 (terminal 3) and A/C-ECU connector C-16 (terminal 1).









NOTE: Also check junction block connector C-214 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. 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 defogger relay connector C-215 (terminal 3) and A/C-ECU connector C-16 (terminal 1) in good condition?

YES: Replace the A/C-ECU. The defogger should operate normally.

NO: Repair or replace the wiring harness. Refer to Harness Connector Inspection. Check that the defogger system works normally.

STEP 14. Measure at defogger connector F-06 in order to check the ground circuit to the defogger connector.




1. Disconnect 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: Is the measured voltage approximately 12 V?

YES: Go to Step 17. .

NO: Go to Step 15.

STEP 15. Check defogger connector F-06 for loose, corroded or damaged terminals, or terminals pushed back in the connector.




Q: Is defogger connector F-06 in good condition?

YES: Go to Step 16.

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

STEP 16. Check the wiring harness between defogger connector F-06 (terminal 1) and ground.




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

YES: Check that the defogger system works normally.

NO: Repair or replace the wiring harness. Refer to Harness Connector Inspection. Check that the defogger system works normally.

STEP 17. Check the 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 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 defogger work normally?

YES: Check that the defogger system works normally.

NO: Repeat from Step 1.