Powertrain Control Module Response Test

Oxygen Sensor And Connector:

NOTE: This test should be performed only after the Oxygen Sensor (O2S) has passed the functional test and heating element test.

NOTE: A four gas analyzer is needed to perform this test.

NOTE: When performing this test it is important that no part of your body contact the vehicle body, as test results will be inaccurate.

CAUTION: NEVER apply voltage directly to any computer sensor wire.

PRECONDITIONING AND SET UP

1. Run the engine at 2,500 rpm for 3 minutes with the transmission in PARK (A/T) or NEUTRAL (M/T), (to ensure vehicle and oxygen sensor are at operating temperature and vehicle is in closed loop).
2. Turn engine OFF, disconnect the oxygen sensor connector. Connect a jumper lead to the O2S signal wire.
3. Start the engine and run at 2,500 rpm for 1 minute, with the transmission in PARK (A/T), or NEUTRAL (M/T).
4. Let idle.

LEAN MIXTURE SIMULATION (PCM SHOULD ATTEMPT TO ENRICH MIXTURE)

1. Touch one hand to the jumper wire from the O2S signal wire and the other hand to battery negative, hold for 10 to 20 seconds.

- The CO and HC readings should increase, as the PCM opens the injectors for longer periods (longer pulse width), to enrich the mixture.

2. If the readings do not change as described, further testing of the oxygen sensor circuit and/or engine control system will be necessary. SEE DIAGNOSIS BY SYMPTOM.

RICH MIXTURE SIMULATION (PCM SHOULD ATTEMPT TO LEAN OUT MIXTURE)

1. Touch one hand to the jumper wire from the O2S signal wire and the other hand to battery positive, hold for 10 to 20 seconds.

- The O2 readings should begin to increase, and the CO reading should decrease.

2. If the readings do not change as described, further testing of the oxygen sensor circuit and/or engine control system will be necessary. SEE DIAGNOSIS BY SYMPTOM.