Diagnostic Test

CHECK FOR AN ACTIVE DTC
NOTE:
If P0688-AUTO SHUTDOWN RELAY SENSE CIRCUIT LOW has set along with any of the O2 SENSOR HEATER CIRCUIT HIGH DTCs, all of the O2 Sensor Heater Control circuits need to be checked for a short to battery voltage.

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.
1. Test drive or operate the vehicle in accordance with the when monitored and set conditions.
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 O2 SENSOR 2/2 HEATER ELEMENT
1. Turn the ignition off.
  NOTE:
  Allow the O2 Sensor to cool down to room temperature.
2. Disconnect the O2 Sensor 2/2 harness connector.
3. Measure the resistance across the O2 Sensor Heater element between the O2 Sensor 2/2 Heater Control terminal and the O2 Sensor 2/2 Heater ground terminal at the component.
  NOTE:
  O2 Sensor 2/2 Heater Element resistance values should be measured at 21.1°C (70°F). The resistance value will vary with different temperature values.
  
  Is the O2 Sensor 2/2 Heater Element resistance between 2.0 and 35.0 Ohms?
  
  Yes
  - Go To 3
  No
  - Verify that there is good pin to terminal contact in the O2 Sensor 2/2 and Powertrain Control Module connectors. If no problems are found, replace the O2 Sensor. Refer to SENSOR, OXYGEN, REMOVAL .
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
CHECK THE (K399) O2 SENSOR 2/2 HEATER CONTROL CIRCUIT
1. Turn the ignition on.
  NOTE:
  Make sure the test light is probing the circuit before actuating the Heater Test or a DTC may set and not allow the actuation.
2. Using a 12-volt test light connected to ground, probe the (K399) O2 Sensor 2/2 Heater Control circuit in the O2 Sensor 2/2 harness connector.
3. With the scan tool, actuate the O2 Sensor 2/2 Heater Test with the Sensor harness connector still disconnected.
  NOTE:
  The test light should be illuminated and bright proportional to the maximum duty cycle allowed by the scan tool. For example, if the scan tool allows 100% actuation, the brightness should be as bright as a direct connection to the battery. If the scan tool allows a maximum 25% actuation, the brightness should be 25% as bright as a direct connection to the battery.
  
  Does the test light illuminate during actuation?
  
  Yes
  - Go To 4
  No
  - Go To 5
CHECK THE O2 SENSOR 2/2 HEATER GROUND CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Turn the ignition off.
2. Measure the resistance between an engine ground and the O2 Sensor 2/2 Heater Ground circuit at the O2 Sensor harness connector.
  Is the resistance below 3.0 Ohms?
  
  Yes
  - Verify that there is good pin to terminal contact in the O2 Sensor 2/2 and Powertrain Control Module connectors. If no problems are found, replace the O2 Sensor. Refer to SENSOR, OXYGEN, REMOVAL .
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Repair the O2 Sensor 2/2 Heater ground circuit for an open or high resistance.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
CHECK THE (K399) O2 SENSOR 2/2 HEATER CONTROL CIRCUIT FOR A SHORT TO VOLTAGE
1. Disconnect the PCM C2 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 the GPEC Diagnostic Adaptor to perform the diagnosis.
2. Connect the (special tool #10436, Adapter, GPEC Diagnostic).
3. Check for continuity between the (K399) O2 Sensor 2/2 Heater Control circuit and all other circuits at the GPEC Adaptor.
  Is there continuity between the (K399) O2 Sensor 2/2 Heater Control circuit and any other circuit?
  
  Yes
  - Repair the (K399) O2 Sensor 2/2 Heater Control circuit for a short to the circuit that showed continuity.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Go To 6
CHECK THE (K399) O2 SENSOR 2/2 HEATER CONTROL CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Turn the ignition off.
2. Measure the resistance of the (K399) O2 Sensor 2/2 Heater Control circuit between the O2 Sensor harness connector and the GPEC Adaptor.
  Is the resistance below 3.0 Ohms?
  
  Yes
  - Go To 7
  No
  - Repair the (K399) O2 Sensor 2/2 Heater Control circuit for an open or high resistance.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
CHECK RELATED PCM AND COMPONENT CONNECTIONS
1. Perform any Service Bulletins that apply.
2. Disconnect all PCM harness connectors.
3. Disconnect all related in-line harness connections (if equipped).
4. Disconnect the related component harness connectors.
5. 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.
6. Reconnect all PCM harness connectors. Be certain that all harness connectors are fully seated and the connector locks are fully engaged.
7. Reconnect all in-line harness connectors (if equipped). Be certain that all connectors are fully seated and the connector locks are fully engaged.
8. Reconnect all related component harness connectors. Be certain that all connectors are fully seated and the connector locks are fully engaged.
9. With the scan tool, erase DTCs.
10. Test drive or operate the vehicle in accordance with the when monitored and set conditions.
11. With the scan tool, read DTCs.
  Did the DTC return?
  
  Yes
  - Replace the Powertrain Control Module in accordance with the Service information. Refer to MODULE, POWERTRAIN CONTROL, REMOVAL .
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  - Test complete.