Diagnostic Test

CHECK FOR AN ACTIVE DTC
1. With the scan tool, read DTCs and record on the repair order.
2. Record the Environmental Data.
3. With the scan tool, erase DTCs.
4. Using the recorded Environmental Data, along with the When Monitored and Set Conditions above, operate the vehicle in the conditions that set the DTC.
5. With the scan tool, read HVAC Module DTCs.
  Did the DTC return?
  
  Yes
  - Go To 2
  No
  - Perform the TESTING FOR AN INTERMITTENT CONDITION procedure. Refer to TESTING FOR AN INTERMITTENT CONDITION .
REPLACE THE REAR DEFROST RELAY AND RECHECK DTCS
1. Replace the Rear Defrost Relay in accordance with the Service Information.
2. With the scan tool, erase DTCs.
3. Using the recorded Environmental Data, along with the When Monitored and Set Conditions above, operate the vehicle in the conditions that set the DTC.
4. With the scan tool, read HVAC Module DTCs.
  Did the DTC return?
  
  Yes
  - Go To 3
  No
  - The new Rear Defrost Relay repaired the problem.
  - Perform the HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .
CHECK THE REAR DEFOGGER RELAY CONTROL CIRCUIT FOR AN OPEN OR HIGH RESISTANCE
1. Turn the Ignition off.
2. Remove the Rear Defrost Relay from the Power Distribution Center (PDC).
3. Disconnect the HVAC Module harness connector.
4. Measure the resistance of the Rear Defogger Relay Control circuit between the relay socket and the HVAC Module harness connector.
  Is the resistance below 3.0 Ohms??
  
  Yes
  - Go To 4
  No
  - Repair the Rear Defogger Relay Control circuit for an open or high resistance.
  - Perform the HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .
CHECK THE REAR DEFOGGER RELAY CONTROL CIRCUIT FOR A SHORT TO GROUND
1. Check for continuity between ground and the Rear Defogger Relay Control circuit at the relay socket.
  Is there continuity between ground and the Rear Defogger Relay Control circuit?
  
  Yes
  - Repair the Rear Defogger Relay Control circuit for a short to ground.
  - Perform the HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .
  No
  - Go To 5
CHECK THE REAR DEFOGGER RELAY CONTROL CIRCUIT FOR A SHORT TO VOLTAGE
1. Turn the ignition on.
2. Measure voltage on the Rear Defogger Relay Control circuit at the relay socket.
  Is there any voltage present?
  
  Yes
  - Repair the Rear Defogger Relay Control circuit for a short to voltage.
  - Perform the HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .
  No
  - Go To 6
CHECK THE REAR DEFOGGER RELAY CONTROL CIRCUIT FOR A SHORT TO ANOTHER CIRCUIT
1. Check for continuity between the Rear Defogger Relay Control circuit and all other circuits at the HVAC Module harness connector.
  Is there continuity between the Rear Defogger Relay Control circuit and any other circuit?
  
  Yes
  - Repair the Rear Defogger Relay Control circuit for a short to another circuit.
  - Perform the HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .
  No
  - Go To 7
CHECK RELATED HARNESS CONNECTIONS
1. Disconnect all HVAC Module 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.
  - Perform a terminal drag test on each connector terminal to verify proper terminal tension.
  Repair any conditions that are found.
5. Reconnect all HVAC Module 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. Using the recorded Environmental Data, along with the When Monitored and Set Conditions above, operate the vehicle in the conditions that set the DTC.
10. With the scan tool, read HVAC Module DTCs.
  Did the DTC return?
  
  Yes
  - Replace the HVAC Module in accordance with the Service information. Refer to MODULE, HVAC, REMOVAL .
  - Perform the HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .
  No
  - The wiring or poor connection problem has been repaired.
  - Perform the HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .