Circuit/System Testing

LY7 and LFW

1. Ignition OFF, disconnect the harness connector at the engine oil pressure (EOP) switch.
2. Ignition OFF, test for less than 1 ohm of resistance between the low reference circuit terminal B and ground.
   • If greater than the specified value, test the circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Engine Oil Pressure Switch parameter is OK.
   • If not the specified value, test the signal circuit terminal A for a short to ground. If the circuit tests normal, replace the ECM.
4. Ignition ON, install a 3-amp fused jumper wire between the signal circuit terminal A and ground. Verify the scan tool Engine Oil Pressure Switch parameter is Low.
   • 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.
5. If all circuits test normal, test or replace the engine oil pressure switch.