Diagnostic Test

WARNING: This page is about a different variant/trim than selected.

CHECK FOR ANY APPLICABLE SERVICE BULLETINS
1. Check for any Service Bulletins or flash updates that may apply.
  Are there any Service Bulletins or flash updates available?
  
  Yes
  - Perform the Service Bulletins or flash update.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Go To 2
CHECK FOR AN ACTIVE DTC
1. Start the engine and allow it to idle long enough for the O2 Sensors to enter closed loop operation (approximately 30 seconds).
2. With the scan tool, read DTCs and record on the repair order.
  Is the DTC active or pending?
  
  Yes
  - Go To 3
  No
  - Perform the INTERMITTENT CONDITION diagnostic procedure. Refer to INTERMITTENT CONDITION .
CHECK THE DOWNSTREAM O2 SENSOR VOLTAGE READINGS ON THE SCAN TOOL
1. With the scan tool, select the Data tab and monitor the voltage readings for the Downstream O2 Sensors.
  NOTE:
  Check the raw voltage readings for the Downstream O2 Sensors to determine if the sensors are switching between 0-1 volt or if one sensor is stuck near 0.0 volts.
  
  Pick the correct scenario below:
  
  Both O2 Sensors are switching between 0-1 volts on the raw O2 Sensor Signal voltage reading
  - Go To 4
  One O2 Sensor is reading 0.0 volts and the other O2 Sensor is switching between 0-1 volts on the raw O2 Sensor Signal voltage reading
  - This indicates a short to ground on the signal circuit of the Downstream O2 Sensor reading near 0.0 volts. Repair the O2 Sensor Signal circuit of the O2 Sensor that is reading near 0.0 volts for a short to ground.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
CHECK FOR A SHORTED DOWNSTREAM O2 SENSOR
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. Disconnect one of the Downstream O2 Sensor harness connectors.
2. With the scan tool, monitor the voltage readings of the Downstream O2 Sensor that is STILL CONNECTED.
  NOTE:
  If the fault is caused by an O2 Sensor that is internally shorted, the other O2 Sensor should change from below one volt to switching between 2.5 - 3.5 volts when the faulty O2 Sensor is disconnected.
3. Reconnect the O2 Sensor harness connector and repeat this step for each of the Downstream O2 Sensors on the vehicle.
  Did the voltages change to approximately 2.5 - 3.5 volts for the O2 Sensors STILL CONNECTED when disconnecting any one of the sensors?
  
  Yes
  - Replace the faulty O2 Sensor 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 THE DOWNSTREAM O2 SENSOR RETURN CIRCUIT FOR A SHORT TO GROUND
1. Turn the ignition off.
2. Disconnect the PCM C2 harness connector.
3. Disconnect the O2 Sensor 1/2 harness connector.
4. Disconnect the O2 Sensor 2/2 harness connector.
5. Check for continuity between ground and the Downstream O2 Sensor Return circuit at the O2 Sensor 1/2 or 2/2 harness connector.
  Is there continuity between ground and the Downstream O2 Sensor Return circuit?
  
  Yes
  - Repair the Downstream O2 Sensor Return circuit for a short to ground.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  No
  - Go To 6
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 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
  - The wiring or poor connection problem has been repaired.
  - Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .