Circuit/System Testing

Ignition OFF, disconnect the harness connector at the G18 high pressure fuel pump.
NOTE: The DMM and test leads must be calibrated to 0 Ω in order to prevent misdiagnosis.
Test for 9-11 Ω at 25°C (77°F) between the low control circuit terminal 1 and the high control circuit terminal 2.
If not within the specified range, replace the G18 high pressure fuel pump.
Measure the resistance between each terminal and the high pressure fuel pump housing. The DMM should display OL.
If less than the specified value, replace the G18 high pressure fuel pump.
Ignition OFF, verify that a test lamp does not illuminate between B+ and the low control circuit terminal 1.
If the test lamp illuminates, test the low control circuit for a short to ground. If the circuit tests normal, replace the K20 ECM.
Ignition ON, verify that a test lamp does not illuminate between ground and the high control circuit terminal 2.
If the test lamp illuminates, test the high control circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.
Ignition ON, command the Fuel Pressure Regulator ON with a scan too. Verify that the test lamp illuminates.
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.
Ignition OFF, connect a test lamp between the low control circuit terminal 1 and B+.
Ignition ON, command the Fuel Pressure Regulator ON with a scan tool. Verify that the test lamp illuminates.
If the test lamp does not illuminate, test the low control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 ECM.
If all circuits and the high pressure fuel pump test normal, replace the K20 ECM.