Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the appropriate HO2S.
- Ignition ON, verify that a test lamp illuminates between the ignition 1 voltage circuit terminal 2 and ground.
- If the test lamp does not illuminate, test the ignition 1 voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition 1 voltage circuit fuse is open, test all components connected to the ignition 1 voltage circuit and replace as necessary.
- Ignition OFF, connect the HO2S circuits together with four 10 amp fused jumper wires.
- Ignition ON, verify a test lamp illuminates between the control circuit terminal 1 and ground.
- If the test lamp does not illuminate, test the heater control circuit for a short to ground or a short to voltage. If the circuit tests normal, test or replace the HO2S sensor.
- The following test must be performed with both the HO2S sensor and the control module connected and operating normally.
- The test lamp must still be connected to ground and the heater control circuit.
- Engine running for one minute, observe the test lamp. The test lamp should flash ON and OFF during the first 30 seconds of the engine running.
- If the test lamp is always ON, test for an open/high resistance in the heater control circuit.
- If all circuits test normal, replace the PCM.
IMPORTANT:
The following test must be performed with both the HO2S sensor and the control module connected and operating normally.
IMPORTANT: