Inspection Procedure 31

Ignition Switch-ST Circuit:

CIRCUIT OPERATION
- The battery positive voltage is supplied to the ECM (terminal 71) via the starter relay during engine cranking. With this, the ECM detects that the engine is being cranked.

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

DIAGNOSIS




STEP 1. Check the ignition switch-ST signal line at ECM connector C-58.
1. Disconnect connector C-58 and measure at the harness side.
2. Turn the ignition switch to "START" position.
3. Measure voltage between terminal 68 and ground.
- The voltage should be 8 volts or more.

4. Turn the ignition switch to "LOCK" (OFF) position. If within specifications, go to Step 2.

If not within specifications, repair the harness wire between ECM connector C-58 and starter relay connector A-18X. Then confirm that the malfunction symptom is eliminated.




STEP 2. Check the circuit at ECM connector C-58.
1. Disconnect connector C-58 and measure at the harness side.
2. Check for continuity between terminal 67 and ground.
- Should be less than 2 ohms .

If less than 2 ohms , go to Step 3.

If open circuit, repair the harness wire between the ECM connector C-58 and the ground. Then confirm that the malfunction symptom is eliminated.




STEP 3. Check harness connector C-58 at the ECM for damage.
If harness connector C-58 is damaged, repair or replace it. Refer to Harness Connector Inspection.

If harness connector C-58 is in good condition, replace the ECM.
Then confirm that the malfunction symptom is eliminated.