Circuit/System Testing
- Ignition OFF.
- Disconnect the harness connector at the G18 high pressure fuel pump.
- Engine operating, verify that a test lamp flashes between the low control circuit terminal 1 and B+.
- If the test lamp is always ON, test the low control circuit for a short to ground. If the circuit tests normal, replace the K20 ECM.
- If the test lamp is always OFF, test the low control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 ECM.
- Ignition ON, verify that a test lamp illuminates between the high control circuit terminal 2 and ground.
- If the test lamp does not illuminate, test the high control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 ECM.
- If all circuits test normal, test or replace the high pressure G18 fuel pump.