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 diagnostic procedure. Refer to TESTING FOR AN INTERMITTENT CONDITION .

1. The ignition must be off when checking the continuity of a circuit.
2. Isolate the circuit by disconnecting the Electronic Control Unit (ECU) and the component harness connectors containing the circuit being tested. Note:  Use the wiring diagram 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. Before testing a circuit, measure the resistance between the two leads of the Digital Volt-Ohm Meter (DVOM). Note:  Resistance in the meter leads can cause an error in the test results.
4. Connect one lead of the DVOM to the circuit being tested at the component harness connector.
5. Connect the other lead to the circuit being tested at the ECU harness connector and measure the resistance of the circuit.

Is the resistance below 3.0 Ohms?

Yes 

• Go To  3

No 

• Repair the circuit for an open or high resistance.
• Perform the HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .

1. The ignition must be off when performing a resistance check to find a short between circuits.
2. Isolate the circuit by disconnecting the ECU and the component harness connectors containing the circuit being tested. Note:  Use the wiring diagram 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 one lead of the DVOM to the circuit being tested at the ECU harness connector.
4. With the other lead of the DVOM probe all other circuits at the ECU harness connector.

Is there continuity between the circuit being tested and any other circuit?

Yes 

• Repair the circuit for a short to another circuit. Use the wiring diagram as a guide to trace the circuits and look for any in-line connectors to help isolate the location of the short.
• Perform the HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .

No 

• Go To  4

1. The ignition must be off when checking the continuity of a circuit.
2. Isolate the circuit by disconnecting the ECU and the component harness connectors containing the circuit being tested. Note:  Use the wiring diagram 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. Before testing a circuit, measure the resistance between the two leads of the DVOM. Note:  Resistance in the meter leads can cause an error in the test results.
4. Connect one lead of the DVOM to the circuit being tested at the component harness connector.
5. Connect the other lead to the circuit being tested at the ECU harness connector and measure the resistance of the circuit.

Is the resistance below 3.0 Ohms?

Yes 

• Go To  5

No 

• Repair the circuit for an open or high resistance.
• Perform the HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .

1. Check the 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  6

Embedded on PCB. 

• Go To  8

1. Disconnect PDC harness connectors C1 and C3,
2. Remove the Defogger Relay.
3. Connect a jumper wire across the relay coil terminals 86 and 85 in the PDC relay socket.
4. Measure the resistance between the PDC connector interface C1, terminal C3 and the PDC connector interface C3, terminal H3.

   Is the resistance below 3.0 Ohms?

   Yes 

   • Go To  7

   No 

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

1. Remove the jumper wire.
2. Reconnect the PDC and HVAC Module harness connectors.
3. Connect a test light between the Defogger Relay coil terminals 86 and 85 in the PDC relay socket.
4. Turn the ignition on.
5. 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  9

1. Disconnect PDC harness connectors C1 and C3,
2. Measure the resistance between the PDC connector interface C1, terminal C3 and the PDC connector interface C3, terminal H3.

   Is the resistance between 72 and 114 Ohms?

   Yes 

   • Go To  9

   No 

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

1. Remove all test equipment and jumper wires from PDC.
2. Disconnect all PDC harness connectors.
3. Check for continuity between the PDC connector interface C3, terminal H3 and all other circuits in all PDC connector interfaces.
   NOTE:

   Continuity between PDC connector interface C1, terminal C4 and PDC connector interface C3, terminal H3 is normal. There is no need to test for a short between these circuits.

   Is there continuity between the PDC connector interface C3, terminal H3 and any other internal PDC circuit?

   Yes 

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

   No 

   • Go To  10

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 .