Diagnostic Test
- CHECK FOR AN ACTIVE DTC
- Start the engine and allow it idle.
- With the scan tool, read DTCs and record on the repair order.
Is the DTC active or pending?
Yes
- Go To 2
No
- Perform the INTERMITTENT CONDITION diagnostic procedure. Refer to INTERMITTENT CONDITION .
- CHECK THE (K79) O2 SENSOR 1/1 HEATER CONTROL CIRCUIT FOR A SHORT TO GROUND
- Turn the ignition off.
- Disconnect the O2 Sensor 1/1 harness connector.
- Disconnect the PCM C2 harness connector.
- Check for continuity between ground and the (K79) O2 Sensor 1/1 Heater Control circuit at the Oxygen Sensor 1/1 harness connector.
Is there continuity between ground and the (K79) O2 Sensor 1/1 Heater Control circuit at the Oxygen Sensor 1/1 harness connector?
Yes
- Repair the (K79) O2 Sensor 1/1 Heater Control circuit for a short to ground.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
No
- Go To 3
- CHECK THE (K79) O2 SENSOR 1/1 HEATER CONTROL CIRCUIT FOR A SHORT TO THE (Z904) SENSOR GROUND
- Check for continuity between the (K79) O2 Sensor 1/1 Heater Control circuit and the (Z904) Sensor Ground circuit at the Oxygen Sensor 1/1 harness connector.
Is there continuity between the (K79) O2 Sensor 1/1 Heater Control circuit and the (Z904) Sensor Ground circuit?
Yes
- Repair the short between the (K79) O2 Sensor 1/1 Heater Control circuit and the (Z904) Sensor Ground circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
No
- Go To 4
- Check for continuity between the (K79) O2 Sensor 1/1 Heater Control circuit and the (Z904) Sensor Ground circuit at the Oxygen Sensor 1/1 harness connector.
- CHECK THE PCM HEATER CONTROL DRIVER FOR PROPER OPERATION
- Reconnect the PCM harness connector.
- Turn the ignition on.
- With the scan tool, actuate the Oxygen Sensor 1/1 control to the maximum allowable percentage.
- Using a 12-volt test light connected to ground, probe the (K79) O2 Sensor 1/1 Heater Control circuit at the Oxygen Sensor 1/1 harness connector.NOTE:
The test light should be illuminated. The brightness will be dependant on the actuation percentage selected.
- With the scan tool, actuate the Oxygen Sensor 1/1 control to the OFF (0%) position.
- Using a 12-volt test light connected to ground, probe the (K79) O2 Sensor 1/1 Heater Control circuit at the Oxygen Sensor 1/1 harness connector.NOTE:
The test light should not be illuminated.
Does the test light illuminate with the actuator ON and not illuminate with the actuator OFF?
Yes
- Replace the O2 Sensor 1/1 in accordance with the Service Information. Refer to SENSOR, OXYGEN, REMOVAL .
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
No
- Go To 5
- CHECK RELATED HARNESS CONNECTIONS
- Disconnect all PCM harness connectors.
- Disconnect all related in-line harness connections (if equipped).
- Disconnect the related component harness connectors.
- Inspect harness connectors, component connectors, and all male and female terminals for the following conditions:
- Proper connector installation.
- Damaged connector locks.
- Corrosion.
- Other signs of water intrusion.
- Weather seal damage (if equipped).
- Bent terminals.
- Overheating due to a poor connection (terminal may be discolored due to excessive current draw).
- Terminals that have been pushed back into the connector cavity.
- Check for spread terminals and verify proper terminal tension.
Repair any conditions that are found.
- Connect all PCM harness connectors. Be certain that all harness connectors are fully seated and the connector locks are fully engaged.
- Connect all in-line harness connectors (if equipped). Be certain that all connectors are fully seated and the connector locks are fully engaged.
- Connect all related component harness connectors. Be certain that all connectors are fully seated and the connector locks are fully engaged.
- With the scan tool, erase DTCs.
- Test drive or operate the vehicle in accordance with the when monitored and set conditions.
- With the scan tool, read DTCs.
Did the DTC return?
Yes
- Replace and program the Powertrain Control Module (PCM) in accordance with the Service Information. Refer to MODULE, POWERTRAIN CONTROL (PCM), REMOVAL .
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
No
- Repair the poor connections.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .