Circuit/System Testing

IMS Switch Circuit Malfunction

1. Ignition OFF, disconnect the harness connector at the AT Inline 20-Way Connector.
2. Ignition ON, verify the scan tool PNP Switch parameter displays In Gear.
   • If not the specified value, test the signal circuit terminal 2 for a short to ground. If the circuit tests normal, replace the ECM.
3. Install a 3A fused jumper wire between the ignition circuit terminal 2 and ground. Verify the scan tool PNP Switch parameter reads Park/Neutral.
   • If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
4. If all circuits test normal, test or replace the IMS switch.

Clutch Start Switch Circuit Malfunction

1. Ignition OFF, disconnect the harness connector at the clutch start switch.
2. Ignition ON, verify a test lamp illuminates between the ignition circuit terminal A and ground.
   • If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.
3. Verify the scan tool Clutch Start Switch parameter reads Released.
   • If not the specified value, test the signal circuit terminal B for a short to voltage. If the circuit tests normal, replace the ECM.
4. Install a 3A fused jumper wire between the ignition circuit terminal A and the signal circuit terminal B. Verify the scan tool Clutch Start Switch parameter reads Applied.
   • If not the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
5. If all circuits test normal, test or replace the Clutch Start Switch.

Crank Relay Circuit Malfunction

1. Ignition OFF, disconnect the CRANK relay.
2. Ignition ON, transmission in Park/Neutral (automatic transmission) or clutch pedal depressed (manual transmission), verify a test lamp illuminates between the relay coil ignition circuit terminal and ground.
   • If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.
3. Verify a test lamp illuminates between the relay switch B+ circuit terminal and ground.
   • If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the CRANK fuse is open, test the relay controlled output circuit for a short to ground.
4. Connect a test lamp between the relay coil ignition circuit terminal and the relay coil control circuit terminal.
IMPORTANT: The engine may begin to crank.
5. Ignition ON, transmission in Park/Neutral (automatic transmission) or clutch pedal depressed (manual transmission), command the Start Relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
   • If the test lamp is always ON, test the relay coil control circuit for a short to ground. If the circuit tests normal, replace the ECM.
   • If the test lamp is always OFF, test the relay coil control circuit for a short to voltage or and open/high resistance. If the circuit tests normal, replace the ECM.
6. Connect the CRANK relay.
7. Install a test lamp between the starter S terminal and ground.
IMPORTANT: The engine may begin to crank.
8. Ignition ON, transmission in Park/Neutral (automatic transmission) or clutch pedal depressed (manual transmission), command the Start Relay ON with a scan tool. The test lamp should illuminate.
   • If the test lamp does not illuminate, test the relay controlled output circuit for an open/high resistance. If the circuit tests normal, test or replace the CRANK relay.
9. If all circuits test normal, test or replace the starter.