Circuit/System Testing

Ignition ON.
Verify the scan tool ECM Ignition 1 Signal parameter is greater than 10 V.
- If 10 V or less
1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
2. Test for infinite resistance between the ignition voltage circuits and ground.
  - If less than infinite resistance, repair the short to ground on the circuit.
  - If infinite resistance
3. 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.
- If greater than 10 V
Ignition OFF, disconnect the KR27 Starter Relay, ignition ON.
Verify a test lamp illuminates between the B+ circuit terminal 30 and ground.
- If the test lamp does not illuminate
1. Ignition OFF.
2. 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, repair the open/high resistance in the positive connection.
- If the test lamp illuminates
Ensure the parking brake is applied and the automatic transmission is in PARK or the manual transmission is in neutral. 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
1. Ignition OFF, disconnect the harness connector at the M64 Starter Motor.
2. Test for infinite resistance between the control circuit terminal 87 ground.
  - If less than infinite resistance, repair the short to ground on the circuit.
  - If infinite resistance
3. 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 M64 Starter Motor.
- If the M64 Starter Motor activates
Test or replace the KR27 Starter Relay.