07 - Inspection Procedure
Defroster Function does not OperateDefogger Circuit:
Connectors:
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
DIAGNOSIS
Required Special Tools:
- MB991223: Test Harness Set
STEP 1. Check the Defogger relay continuity.
Q: Is the Defogger relay continuity in good condition?
YES: Go to Step 2.
NO: Replace the defogger relay. The defogger system should work normally.
STEP 2. 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 3.
NO: Refer to Defogger.
STEP 3. 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 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 6.
NO: Go to Step 4.
STEP 4. Check defogger relay connector C-215 for damage.
Q: Is defogger relay connector C-215 in good condition?
YES: Go to Step 5.
NO: Repair or replace the connector. Refer to Harness Connector Inspection. Check that the air conditioning works normally.
STEP 5. Check the wiring harness between defogger relay connector C-215 and the ignition switch (IG2).
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 defogger relay connector C-215 and the ignition switch (IG2) in good condition?
YES: Check that the air conditioning works normally.
NO: Repair the wiring harness. Check that the air conditioning works normally.
STEP 6. 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. Ignition switch: ON
3. 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 9.
NO: Go to Step 7.
STEP 7. Check defogger relay connector C-215 for damage.
Q: Is defogger relay connector C-215 in good condition?
YES: Go to Step 8.
NO: Repair or replace the connector. Refer to Harness Connector Inspection. Check that the air conditioning works normally.
STEP 8. Check the wiring harness between defogger relay connector C-215 and fusible link 1.
NOTE: Also check intermediate connector C-126 and junction block connector C-212. If intermediate connector C-126 or junction block connector C-212 is damaged, repair or replace the connector as described in Harness Connector Inspection.
Q: Is the wiring harness between defogger relay connector C-215 and fusible link 1. in good condition?
YES: Check that the air conditioning works normally.
NO: Repair the wiring harness. Check that the air conditioning works normally.
STEP 9. Measure the voltage at defogger connector F-16.
1. Disconnect defogger switch connector F-16, and measure the voltage at the wiring harness side.
2. Ignition switch: ON
3. Defogger switch: ON (measurement must be done within nine minutes after defogger switch is turned on)
4. 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 12.
NO: Go to Step 10.
STEP 10. Check defogger relay connector C-215 and defogger connector F-16 for damage.
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 air conditioning works normally.
STEP 11. Check the wiring harness between defogger relay connector C-215 and defogger connector F-16.
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 defogger relay connector C-215 and defogger connector F-16 in good condition?
YES: The defogger should operate normally.
NO: Repair or replace the wiring harness. Refer to Harness Connector Inspection. Check that the air conditioning works normally.
STEP 12. 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.
- 2 Ohm or less
Q: Does the measured resistance value correspond with this range?
YES: Go to Step 15.
NO: Go to Step 13.
STEP 13. Check defogger connector F-06 for damage.
Q: Is 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 air conditioning works normally.
STEP 14. Check the wiring harness between defogger connector F-06 and ground.
Q: Is the wiring harness between defogger connector F-06 and ground in good condition?
YES:Go to STEP 15.
NO: Repair or replace the wiring harness. Refer to Harness Connector Inspection. Check that the air conditioning works normally.
STEP 15. Check defogger relay connector C-215 and A/C-ECU connector C-16 for damage.
Q: Are defogger relay connector C-215 and A/C-ECU connector C-16 in good condition?
YES: Go to Step 16.
NO: Repair or replace the connector. Refer to Harness Connector Inspection. Check that the air conditioning works normally.
STEP 16. Check the wiring harness between defogger relay connector C-215 and A/C-ECU connector C-16.
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 defogger relay connector C-215 and A/C-ECU connector C-16 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 air conditioning works normally.