Diagnostic Test

CHECK FOR AN ACTIVE DTC
NOTE:
This DTC must be active and the appropriate trailer must be used for the results of this test to be valid.
1. With the scan tool, read Trailer Tow Module (TTM) 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 TTM DTCs.
  Did the DTC return?
  
  Yes
  - Go To 2
  No
  - Perform the TESTING FOR INTERMITTENT CONDITIONS procedure. Refer to INTERMITTENT CONDITION .
CHECK THE TRAILER WIRING/REAR FOG LAMPS
1. Turn the Rear Fog Lamps off.
2. Turn the ignition off.
3. Disconnect the trailer electrical connection from the vehicle.
4. Turn the ignition on.
5. Turn the Rear Fog Lamps on.
6. With the scan tool, read TTM DTCs.
  Is the DTC as active?
  
  Yes
  - Go To 3
  No
  - The trailer Rear Fog Lamp wiring is shorted to ground, refer the customer to an authorized trailer dealer.
CHECK THE TRAILER REAR FOG LAMP DRIVER CIRCUIT FOR A SHORT TO GROUND
1. Turn the Rear Fog Lamps off.
2. Turn the ignition off.
3. Disconnect the TTM harness connector.
4. Check for continuity between ground and the Trailer Rear Fog Lamp Driver circuit at the vehicle's trailer harness connector.
  Is there continuity between ground and the Trailer Rear Fog Lamp Driver circuit?
  
  Yes
  - Repair the short to ground in the Trailer Rear Fog Lamp Driver circuit.
  - Perform the TTM VERIFICATION TEST. Refer to TTM VERIFICATION TEST .
  No
  - Go To 4
CHECK THE TRAILER TOW MODULE
1. Connect the TTM harness connector.
2. Turn the ignition on.
3. Turn the Rear Fog Lamps on.
  NOTE:
  The test light must illuminate brightly. Compare the brightness to that of a direct connection to the battery.
4. Connect a 12-volt test light between ground and the Trailer Rear Fog Lamp Driver circuit at the vehicle's trailer harness connector.
  Does the test light illuminate on and off brightly?
  
  Yes
  - Perform the TESTING FOR INTERMITTENT CONDITIONS procedure. Refer to INTERMITTENT CONDITION .
  No
  - Go To 5
CHECK RELATED HARNESS CONNECTIONS
1. Disconnect all TTM 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 TTM 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 TTM DTCs.
  Did the DTC return?
  
  Yes
  - Replace the Trailer Tow Module (TTM) in accordance with the Service Information.
  - Perform the TTM VERIFICATION TEST. Refer to TTM VERIFICATION TEST .
  No
  - Perform the TTM VERIFICATION TEST. Refer to TTM VERIFICATION TEST .
  - Test complete.