Diagnostic Test

1. With the scan tool, read DTCs in all Electronic Control Units (ECUs) and record on the repair order.
2. With the scan tool, run a Vehicle Scan Report or record the Environmental Data.
3. With the scan tool, erase DTCs.
4. Turn the ignition off for at least 10.0 seconds.
5. Turn the ignition on.
6. Using the recorded Environmental Data and the When Monitored Conditions, operate the vehicle in the conditions that set the DTC.
7. With the scan tool, read 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 .

1. The ignition must be off when checking a circuit for continuity to ground.
2. Isolate the circuit by disconnecting the Electronic Control Unit (ECU) and the component harness connectors containing the circuit being tested. Note:  Use the appropriate SYSTEM WIRING DIAGRAMS as a guide to follow the path of the circuit. Check the disconnected connectors and related harnesses for damage, corrosion, and loose fitting terminals.
3. Connect the negative lead of the Digital Volt-Ohm Meter (DVOM) to a known good ground.
4. With the positive lead of the DVOM, probe the circuit being tested at the component harness connector and check for continuity between the circuit and ground.

Is there continuity between ground and the circuit being tested?

Yes 

• Repair the circuit for a short to ground. Use the appropriate SYSTEM WIRING DIAGRAMS as a guide to trace the circuit and identify any in-line connectors that may help isolate the location of the short.
• Perform the HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .

No 

• Go To  3

1. Check the Power Distribution Center (PDC) layout in the wiring information to determine if the Defogger Relay is removable or if it is embedded on the Printed Circuit Board (PCB) of the PDC.

Is the Relay removable or is it embedded on the PCB?

Removable. 

• Go To  4

Embedded on PCB. 

• Go To  6

1. Remove the Defogger Relay.
2. Disconnect PDC harness connector C3.
3. Check for continuity between ground and the (C115) Defogger Relay Control circuit at the PDC C3 connector interface.

   Is there continuity between ground and the (C115) Defogger Relay Control circuit inside the PDC?

   Yes 

   • Replace the PDC in accordance with the Service Information.
   • Perform the HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .

   No 

   • Go To  5

1. Reconnect the PDC and HVAC Module harness connectors.
2. Connect a test light between the Defogger Relay coil terminals 86 and 85 in the PDC relay socket.
3. Turn the ignition on.
4. Turn the Rear Window Defogger on.

   Is the test light illuminated and bright?

   Yes 

   • Replace the Defogger Relay in accordance with the Service Information.
   • Perform the HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .

   No 

   • Go To  7

1. Disconnect all PDC harness connectors.
2. Check for continuity between the PDC connector interface C3, terminal H7 and all other circuits in all PDC connector interfaces.
   NOTE:

   Continuity between PDC connector interface C1, terminal C4 and PDC connector interface C3, terminal H7 is normal. There is no need to test for a short between these circuits.

   Is there continuity between the PDC connector interface C3, terminal H7 and any other circuit inside the PDC?

   Yes 

   • Replace the PDC in accordance with the Service Information.
   • Perform the HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .

   No 

   • Go To  7

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 AND INSTALLATION .
    • 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 .