Inspection Procedure 8
Defroster Function does not Operate.Defogger Circuit Part 1:
Defogger Circuit Part 2:
CIRCUIT OPERATION
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
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 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 defogger relay continuity.
Follow the table above to check the defogger relay for continuity.
Q: Is the Defogger relay continuity 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-206.
1. Disconnect 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 defogger relay connector C-206 for damage.
Q: Is defogger relay connector C-206 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-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 defogger relay connector C-206(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-206.
1. Disconnect defogger relay connector C-206, and measure the voltage at the junction block side.
2. Ignition switch: ON
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 defogger relay connector C-206 for damage.
Q: Is defogger relay connector C-206 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-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 defogger relay connector C-206 (terminal 1) and ignition switch 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-206 and A/C-ECU connector C-06 for damage.
Q: Are 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. Refer to Harness Connector Inspection. Check that the defogger system works normally.
STEP 11. Check the wiring harness between 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 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 defogger should operate normally.
NO: Repair or replace the wiring harness. Refer to Harness Connector Inspection. Check that the defogger system works normally.
STEP 12. 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: Go to Step 13.
NO: Refer to Defogger.
STEP 13. Measure at defogger connector F-01 to check the ground circuit to the defogger connector.
1. Disconnect 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 defogger connector F-01 for damage.
Q: Is defogger connector F-01 in good condition?
YES: Go to Step 15.
NO: Repair or replace the connector. Refer to Harness Connector Inspection. Check that the defogger system works normally.
STEP 15. Check the wiring harness between defogger connector F-01 (terminal 1) and ground.
Q: Is the wiring harness between defogger connector F-01 (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 16. Check defogger relay connector C-206 and defogger connector F-04 for damage.
Q: Are defogger relay connector C-206 and defogger connector F-04 in good condition?
YES: Go to Step 17.
NO: Repair or replace the connector. Refer to Harness Connector Inspection. Check that the defogger system works normally.
STEP 17. Check the wiring harness between defogger relay connector C-206 (terminal 4) and 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 defogger relay connector C-206 (terminal 4) and defogger connector F-01 (terminal 1) 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.