Inspection Procedure 30

INSPECTION PROCEDURE 30
Electrical load switch system
Electrical Load Switch Circuit




WIRING DIAGRAM and CONNECTOR VIEW

CIRCUIT OPERATION
- When the headlight switch, defogger switch or blower switch is turned "ON," the battery positive voltage is applied on the ECM (terminal 24).
With this, the ECM detects that the headlight switch, defogger switch or blower switch, having a large electrical load, has turned "ON." The ECM compensates for the electrical load by immediately increasing idle rpm.

TROUBLESHOOTING HINTS
The most likely causes for this case:
- Improper connector contact, open circuit or short-circuited harness wire of headlight relay circuit.
- Improper connector contact, open circuit or short-circuited harness wire of defogger relay circuit.
- Improper connector contact, open circuit or short-circuited harness wire of blower switch circuit.
- Malfunction of the ECM.

DIAGNOSIS




STEP 1. Check the circuit at the ECM connector C-51.
(1) Disconnect connector C-51 and measure at the harness side.
(2) Turn the ignition switch "ON."
(3) Turn the lighting switch "ON."
(4) Measure the voltage between terminal 24 and ground.
- Voltage should be approximately 12 volts (battery positive voltage).
(5) Turn the lighting switch "OFF."
(6) Turn the ignition switch "OFF."
If within specifications, go to Step 2.
If not within specifications, check the harness wire and connector between the ECM and the headlight relay. Refer to Headlight. Then confirm that the malfunction symptom is eliminated.




STEP 2. Check the circuit at the ECM connector C-51.
(1) Disconnect connector C-51 and measure at the harness side.
(2) Turn the ignition switch "ON."
(3) Turn the rear defogger switch "ON."
(4) Measure the voltage between terminal 24 and ground.
- Voltage should be approximately 12 volts (battery positive voltage).
(5) Turn the rear defogger switch "OFF."
(6) Turn the ignition switch "OFF."
If within specifications, go to Step 3.
If not within specifications, check the harness wire and connector between the ECM and the defogger relay. Refer to Rear Window Defogger. Then confirm that the malfunction symptom is eliminated.




STEP 3. Check the circuit at the ECM connector C-51.
(1) Disconnect connector C-51 and measure at the harness side.
(2) Turn the ignition switch "ON."
(3) Turn the blower switch "ON."
(4) Measure the voltage between terminal 24 and ground.
- Voltage should be approximately 12 volts (battery positive voltage).
(5) Turn the blower switch "OFF."
(6) Turn the ignition switch "OFF."
If within specifications, go to Step 4.
If not within specifications, check the harness wire and connector between the ECM and the blower switch. Refer to On-vehicle Service. Then confirm that the malfunction symptom is eliminated.




STEP 4. Check harness connector C-51 at the ECM for damage.
If harness connector C-51 is damaged, repair or replace it. Refer to Harness Connector Inspection.
If harness connector C-51 is in good condition, replace the ECM.
Then confirm that the malfunction symptom is eliminated.