Inspection Procedure 9

INSPECTION PROCEDURE 9: Rear Window Defogger Function does not Operate.






























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 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 1, "Malfunction of the A/C-ECU power supply system Inspection Procedure 10."
STEP 2. Check rear window defogger relay connector C-205 for loose, corroded or damaged terminals, or terminals pushed back in the connector.





Q. Is rear window defogger relay connector C-205 in good condition?

YES Go to Step 3.

NO Repair or replace the connector. Harness Connector Inspection.

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.

STEP 4. Check A/C-ECU connector C-15 and rear window defogger connector F-01 for loose, corroded or damaged terminals, or terminals pushed back in the connector.













Q. Is A/C-ECU connector C-15 and rear window defogger connector F-01 in good condition?

YES Go to Step 5.

NO Repair or replace the connector. Harness Connector Inspection.

STEP 5. Measure the voltage at rear window defogger connector F-01.









(1)Disconnect rear window defogger connector F-01, and measure the voltage at the harness side.









(2)Disconnect A/C-ECU connector C-15 and ground harness side terminal No.8.
(3)Turn the ignition switch to the "ON" position.





(4)Measure the voltage between rear window defogger connector F-01 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 12.

NO Go to Step 6.

STEP 6. Measure the voltage at rear window defogger relay connector C-205.





(1)Disconnect rear window defogger relay connector C-205, 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 volts?

YES Go to Step 8.

NO Go to Step 7.

STEP 7. Check the wiring harness between rear window defogger relay connector C-205 (terminal 5) and the fusible link (1).









NOTE:
Also check intermediate connector C-24 and junction block connector C-204 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If intermediate connector C-24 and junction block connector C-204 is damaged, repair or replace the connector as described in Harness Connector Inspection Harness Connector Inspection.

Q. Is the wiring harness between rear window defogger relay connector C-205 (terminal 5) and the fusible link (1) in good condition?

YES It can be assumed that this malfunction is intermittent. How to Cope With Intermittent Malfunctions.

NO Repair or replace the wiring harness. Harness Connector Inspection.

STEP 8. Measure the voltage at rear window defogger relay connector C-205.





(1)Disconnect rear window defogger relay connector C-205, 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 10.

NO Go to Step 9.

STEP 9. Check the wiring harness between rear window defogger relay connector C-205 (terminal 1) and ignition switch (IG2).





NOTE:
Also check junction block connector C-202 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If junction block connector C-202 is damaged, repair or replace the connector as described in Harness Connector Inspection Harness Connector Inspection.

Q. Is the wiring harness between rear window defogger relay connector C-205 (terminal 1) and ignition switch (IG2) in good condition?

YES It can be assumed that this malfunction is intermittent. How to Cope With Intermittent Malfunctions.

NO Repair or replace the wiring harness. Harness Connector Inspection.

STEP 10. Check the wiring harness between rear window defogger relay connector C-205 (terminal 3) and A/C-ECU connector C-15 (terminal 8).









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 in Harness Connector Inspection Harness Connector Inspection.

Q. Is the wiring harness between rear window defogger relay connector C-205 (terminal 3) and A/C-ECU connector C-15 (terminal 8) in good condition?

YES Go to Step 11.

NO Repair or replace the wiring harness. Harness Connector Inspection.

STEP 11. Check the wiring harness between rear window defogger relay connector C-205 (terminal 4) and rear window defogger connector F-01 (terminal 1).

















NOTE:
Also check junction block connector C-208 and intermediate connector D-43 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If junction block connector C-208 and intermediate connector D-43 is damaged, repair or replace the connector as described in Harness Connector Inspection Harness Connector Inspection.

Q. Is the wiring harness between rear window defogger relay connector C-205 (terminal 4) and rear window defogger connector F-01 (terminal 1) in good condition?

YES It can be assumed that this malfunction is intermittent. How to Cope With Intermittent Malfunctions.

NO Repair or replace the wiring harness. Harness Connector Inspection.

STEP 12. Check rear window defogger connector F-04 for loose, corroded or damaged terminals, or terminals pushed back in the connector.









Q. Is rear window defogger connector F-04 in good condition?

YES Go to Step 13.

NO Repair or replace the connector. Harness Connector Inspection.

STEP 13. Measure the resistance at rear window defogger connector F-04.









(1)Disconnect rear window defogger connector F-04, and measure the resistance at the wiring harness side.





(2)Measure the resistance value between terminal 1 and ground.
OK: Less than 2 ohms

Q. Does the measured resistance value correspond with this range?

YES Go to Step 15.

NO Go to Step 14.

STEP 14. Check the wiring harness between rear window defogger connector F-04 (terminal 1) and ground.









Q. Is the wiring harness between rear window rear window defogger connector F-04 (terminal 1) and ground in good condition?

YES It can be assumed that this malfunction is intermittent. How to Cope With Intermittent Malfunctions.

NO Repair or replace the wiring harness. Harness Connector Inspection.

STEP 15. 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.

NO Repair the rear window defogger.