Diagnostic Test
- 1) 2/2 OXYGEN SENSOR VOLTAGE NOTE: If an O2 sensor signal circuit is shorted to voltage, all O2 sensor voltage readings displayed on the scan tool will be approximately 5.0 volts. Diagnose the sensor that set the most current DTC.
Start the engine and allow it to idle for at least 60 seconds.
WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.With a scan tool, select View DTCs.
Is the DTC Active at this time?
Yes
- Go to step 2).
No
- Refer to *CHECKING FOR AN INTERMITTENT DTC diagnostic procedure.
- 2) (K243) O2 2/2 SIGNAL CIRCUIT SHORTED TO VOLTAGE
Turn the ignition off.
Disconnect the 2/2 Oxygen Sensor harness connector.
Disconnect the C1 Powertrain Control Module (PCM) harness connector.
Turn the ignition on.
Measure the voltage of the (K243) O2 2/2 Signal circuit in the 2/2 Oxygen Sensor harness connector.
NOTE: Measure the voltage in reference to ground, not the (K904) O2 Return (Down) circuit.Is there any voltage present?
Yes
- Repair the short to voltage in the (K243) O2 2/2 Signal circuit.
- Perform PCM VERIFICATION TEST .
No
- Go to step 3).
- 3) (K904) O2 RETURN (DOWN) CIRCUIT SHORTED TO VOLTAGE
Measure the voltage on the (K904) O2 Return (Down) circuit in the 2/2 Oxygen Sensor harness connector.
Is there any voltage present?
Yes
- Repair the short to voltage in the (K904) O2 Return (Down) circuit.
- Perform PCM VERIFICATION TEST .
No
- Go to step 4).
- 4) (K243) O2 2/2 SIGNAL CIRCUIT SHORTED TO THE (K399) O2 2/2 HEATER CONTROL CIRCUIT
Turn the ignition off.
Measure the resistance between the (K243) O2 2/2 Signal circuit and the (K399) O2 2/2 Heater Control circuit the 2/2 Oxygen Sensor harness connector.
Is the resistance below 100.0 ohms?
Yes
- Repair the short between the (K243) O2 2/2 Signal circuit and the (K399) O2 2/2 Heater Control circuit.
- Perform PCM VERIFICATION TEST .
No
- Go to step 5).
- 5) 2/2 OXYGEN SENSOR
Turn the ignition off.
Connect the Powertrain Control Module (PCM) harness connector.
Connect a jumper wire between the (K243) O2 2/2 Signal circuit and the (K904) O2 Return (Down) circuit in the 2/2 Oxygen Sensor harness connector.
Turn the ignition on.
With a scan tool, monitor the 2/2 Oxygen Sensor voltage.
Is the voltage between 2.3 and 2.7 volts with the jumper wire in place?
Yes
- Verify that there is good pin to terminal contact in the Oxygen Sensor and Powertrain Control Module connectors. If OK, replace the 2/2 O2 Sensor.
- Perform PCM VERIFICATION TEST .
No
- Go to step 6).
- 6) (K243) O2 2/2 SIGNAL CIRCUIT OPEN
Turn the ignition off.
If necessary, remove the jumper wire from between the (K243) O2 2/2 Signal circuit and the (K904) O2 Return (Down) circuit in the 2/2 Oxygen Sensor harness connector.
Disconnect the C1 Powertrain Control Module (PCM) harness connector.
CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals, resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis.Measure the resistance of the (K243) O2 2/2 Signal circuit between the 2/2 Oxygen Sensor harness connector and the appropriate terminal of special tool #8815.
Is the resistance below 5.0 ohms?
Yes
- Go to step 7).
No
- Repair the open in the (K243) O2 2/2 Signal circuit for an open.
- Perform PCM VERIFICATION TEST .
- 7) (K904) O2 RETURN (DOWN) CIRCUIT OPEN OR HIGH RESISTANCE
Measure the resistance of the (K904) O2 Return (Down) circuit between the 2/2 Oxygen Sensor harness connector and the appropriate terminal of special tool #8815.
Is the resistance below 5.0 ohms?
Yes
- Go to step 8).
No
- Repair the open in the (K904) O2 Return (Down) circuit.
- Perform PCM VERIFICATION TEST .
- 8) POWERTRAIN CONTROL MODULE (PCM)
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the 2/2 Oxygen Sensor and the Powertrain Control Module (PCM).
Look for any chafed, pierced, pinched, or partially broken wires.
Look for broken, bent, pushed out or corroded terminals.
Verify that there is good pin to terminal contact in the Oxygen Sensor and Powertrain Control Module connectors.
Refer to any Technical Service Bulletins that may apply.
Were any problems found?
Yes
- Repair as necessary.
- Perform PCM VERIFICATION TEST .
No
- Replace and program the Powertrain Control Module (PCM) in accordance with the Service Information.
- Perform PCM VERIFICATION TEST .