Inspection Procedure 8

INSPECTION PROCEDURE 8: Defogger Function 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 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
- 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 10, "Malfunction of the A/C-ECU power supply system." Inspection Procedure 10

STEP 2. Check rear window defogger relay connector C-201 for loose, corroded or damaged terminals, or terminals pushed back in the connector.







Q: Is rear window defogger relay connector C-201 in good condition?

YES : Go to Step 3.

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

STEP 4. Check rear window defogger connector D-39 for loose, corroded or damaged terminals, or terminals pushed back in the connector.







Q: Is rear window defogger connector D-39 in good condition?

YES : Go to Step 5.

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

STEP 5. Measure the voltage at rear window defogger connector D-39.







1. Disconnect rear window defogger connector D-39, and measure the voltage at the harness side.







2. Disconnect A/C-ECU connector C-15 and ground harness side terminal No.27.
3. Turn the ignition switch to the "ON" position.







4. Measure the voltage between rear window defogger connector D-39 terminal No.1 and ground.
- The measured value should be approximately 12 volts (battery positive voltage).

Q: Is the measured voltage approx. 12 volts?

YES : Go to Step 13.

NO : Go to Step 6.

STEP 6. Measure the voltage at rear window defogger relay connector C-201.







1. Disconnect rear window defogger relay connector C-201, 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 approx. 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-201 (terminal 5) and the fusible link (1).












NOTE: Also check intermediate connector C-29 and junction block connector C-216 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If intermediate connector C-29 and junction block connector C-216 is damaged, repair or replace the connector as described.

Q: Is the wiring harness between rear window defogger relay connector C-201(terminal 5) and the fusible link (1) in good condition?

YES : It can be assumed that this malfunction is intermittent.

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

STEP 8. Measure the voltage at rear window defogger relay connector C-201.







1. Disconnect rear window defogger relay connector C-201, 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 approx. 12 volts?

YES : Go to Step 10.

NO : Go to Step 9.

STEP 9. Check the wiring harness between rear window defogger relay connector C-201 (terminal 1) and ignition switch (IG2).







NOTE: Also check junction block connector C-215 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If junction block connector C-215 is damaged, repair or replace the connector as described.

Q: Is the wiring harness between rear window defogger relay connector C-201 (terminal 1) and ignition switch (IG2) in good condition?

YES : It can be assumed that this malfunction is intermittent.

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

STEP 10. Check A/C-ECU connector C-15 for loose, corroded or damaged terminals, or terminals pushed back in the connector.







Q: Is A/C-ECU connector C-15 in good condition?

YES : Go to Step 11.

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

STEP 11. Check the wiring harness between rear window defogger relay connector C-201 (terminal 3) and A/C-ECU connector C-15 (terminal 8).







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.

Q: Is the wiring harness between rear window defogger relay connector C-201 (terminal 3) and A/C-ECU connector C-15 (terminal 8) in good condition?

YES : Go to Step 12.

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

STEP 12. Check the wiring harness between rear window defogger relay connector C-201 (terminal 4) and rear window defogger connector D-39 (terminal 1).







NOTE: Also check junction block connector C-204 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If junction block connector C-204 is damaged, repair or replace the connector as described.

Q: Is the wiring harness between rear window defogger relay connector C-201 (terminal 4) and rear window defogger connector D-39 (terminal 1) in good condition?

YES : It can be assumed that this malfunction is intermittent.

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

STEP 13. Check rear window defogger connector D-38 for loose, corroded or damaged terminals, or terminals pushed back in the connector.







Q: Are rear window defogger connector D-38 in good condition?

YES : Go to Step 14.

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

STEP 14. Measure the resistance at rear window rear window defogger connector D-38.







1. Disconnect rear window defogger connector D-38, 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 D-38 (terminal 1) and the ground.







Q: Is the wiring harness between rear window defogger connector D-38 (terminal 1) and the ground in good condition?

YES : Check that the defogger system works normally.

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

STEP 16. Check capacitor connector D-40 for loose, corroded or damaged terminals, or terminals pushed back in the connector.







Q: Is capacitor connector D-40 in good condition?

YES : Go to Step 17.

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

STEP 17. Check the wiring harness between capacitor connector D-40 (terminal 1) and junction block connector C-204 (terminal 1).







Q: Is the wiring harness between capacitor connector D-40 (terminal 1) and junction block connector C-204 (terminal 1) in good condition?

YES : Go to Step 18.

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

STEP 18. 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 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 : Replace the A/C-ECU. Check that the defogger system works normally.

NO : Repair the defogger.