Inspection Procedure 28
INSPECTION PROCEDURE 28Ignition Switch-ST System
Ignition Switch-ST System Circuit
WIRING DIAGRAM and CONNECTOR VIEW
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 the ECM connector C-57.
(1) Disconnect connector C-57 and measure at the harness side.
(2) Turn the ignition switch to "ST."
(3) Measure voltage between terminal 71 and ground.
- The voltage should be 8 volts or more.
(4) Turn the ignition switch "OFF."
If within specifications, go to Step 2.
If not within specifications, repair the harness wire between the ECM connector C-57 and the starter relay connector A-50X. Then confirm that the malfunction symptom is eliminated.
STEP 2. Check the circuit at the ECM connector C-57.
(1) Disconnect connector C-57 and measure at the harness side.
(2) Check for continuity between terminal 91 and ground.
- There should be continuity (0 ohms).
If continuity, go to Step 3.
If no continuity, repair the harness wire between the ECM connector C-57 and the ground. Then confirm that the malfunction symptom is eliminated.
STEP 3. Check harness connector C-57 at the ECM for damage.
If harness connector C-57 is damaged, repair or replace it. Refer to Harness Connector Inspection.
If harness connector C-57 is in good condition, replace the ECM.
Then confirm that the malfunction symptom is eliminated.