Diagnostic Test

CHECK FOR AN ACTIVE DTC
1. Start the engine and allow it to reach normal operating temperature.
  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 may result in possible serious or fatal injury.
2. 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
1. Turn the ignition off.
2. Disconnect the Oxygen Sensor 1/1 harness connector.
3. Disconnect the Powertrain Control Module (PCM) C2 harness connector.
4. Check for continuity between ground and the (K79) O2 Sensor 1/1 Heater Control circuit in the Oxygen Sensor 1/1 harness connector.
  Is there continuity between ground and the (K79) O2 Sensor 1/1 Heater Control circuit?
  
  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 FOR THE (K79) O2 SENSOR 1/1 HEATER CONTROL CIRCUIT SHORTED TO THE (Z909) GROUND CIRCUIT
1. Check for continuity between the (K79) O2 Sensor 1/1 Heater Control circuit and the (Z909) Ground circuit in the Oxygen Sensor 1/1 harness connector.
  Is there continuity between the (Z909) Ground circuit in the Oxygen Sensor 1/1 harness connector and the (K79) O2 Sensor 1/1 Heater Control circuit?
  
  Yes
  - Repair the short between the (K79) O2 Sensor 1/1 Heater Control circuit and the (Z909) Ground circuit.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Go To 4
CHECK THE PCM OXYGEN SENSOR 1/1 HEATER CONTROL OPERATION
1. Connect the Powertrain Control Module (PCM) C2 harness connector.
2. Turn the ignition on.
3. With the scan tool, actuate the Oxygen Sensor 1/1 control to the maximum allowable percentage.
4. Using a 12-volt test light connected to ground, check the (K79) O2 Sensor 1/1 Heater Control circuit at the Oxygen Sensor 1/1 harness connector.
  NOTE:
  The test light should flash dimly.
5. With the scan tool, actuate the Oxygen Sensor 1/1 control to OFF (0%).
6. Using a 12-volt test light connected to ground, check the (K79) O2 Sensor 1/1 Heater Control circuit in the Oxygen Sensor 1/1 harness connector.
  NOTE:
  The test light should not be illuminated with the control actuated OFF (0%).
  
  Does the test light flash dimly with the output control ON (25%) and not illuminated with the output control OFF (0%)?
  
  Yes
  - Replace the Oxygen Sensor 1/1 in accordance with the Service Information. Refer to SENSOR, OXYGEN, REMOVAL AND INSTALLATION .
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Go To 5
CHECK RELATED HARNESS CONNECTIONS
1. Disconnect all PCM harness connectors.
2. Disconnect all related in-line harness connections (if equipped).
3. Disconnect the related component harness connectors.
4. 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.
5. Reconnect all PCM harness connectors. Be certain that all harness connectors are fully seated and the connector locks are fully engaged.
6. Reconnect all in-line harness connectors (if equipped). Be certain that all connectors are fully seated and the connector locks are fully engaged.
7. Reconnect all related component harness connectors. Be certain that all connectors are fully seated and the connector locks are fully engaged.
8. With the scan tool, erase DTCs.
9. Test drive or operate the vehicle in accordance with the when monitored and set conditions.
10. 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 AND INSTALLATION .
  - 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 .