Circuit/System Testing
- Ignition ON.
- Verify the scan tool ECM Ignition 1 Signal parameter is greater than 10 V.
- Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
- Test for infinite resistance between the ignition voltage circuits and ground.
- If less than infinite resistance, repair the short to ground on the circuit.
- Test for less than 2 Ω in the control circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, replace the K20 Engine Control Module.
- Ignition OFF, disconnect the KR27 Starter Relay, ignition ON.
- Verify that a test lamp illuminates between the B+ circuit terminal 30 and ground.
- If the test lamp does not illuminate and the circuit fuse is good
- Ignition OFF.
- Test for less than 2 Ω in the B+ circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, verify the fuse is not open and there is voltage at the fuse.
- If the test lamp does not illuminate and the circuit fuse is open
- Ignition OFF.
- Test for infinite resistance between the B+ circuit and ground.
- If less than infinite resistance, repair the short to ground on the circuit.
- Disconnect X1 harness connector at the M64 Starter Motor.
- Test for infinite resistance between the control circuit terminal 87 and ground.
- If less than infinite resistance, repair the short to ground on the circuit.
- If infinite resistance, replace the M64 Starter Motor.
- If the test lamp illuminates
- Ensure the parking brake is applied and the T12 Transmission is in PARK. Momentarily install a 30 A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87.
- Verify the M64 Starter Motor is activated.
- If the M64 Starter Motor does not activate
- Disconnect the X1 harness connector at the M64 Starter Motor.
- Test for less than 2 Ω in the control circuit end to end.
- If greater the 2 Ω, repair the open/high resistance in the circuit.
- If less than 2 Ω, replace the M64 Starter Motor.
- If the M64 Starter Motor activates
- Test or replace the KR27 Starter Relay.