Diagnostic Test

CHECK FOR AN ACTIVE DTC
1. Turn the ignition on.
2. Turn the Park Lamps on.
3. With the scan tool, read the Body Control Module (BCM) DTCs and record on the repair order.
  Is the DTC active?
  
  Yes
  - Go To 2
  No
  - The condition or conditions that originally set this DTC are not present at this time. Using the wiring diagrams as a guide, check all related splices and connectors for signs of water intrusion, corrosion, pushed out or bent terminals and correct pin tension. If no problems are found, test complete.
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
CHECK THE (L77) LEFT FRONT PARK LAMP DRIVER CIRCUIT FOR A SHORT TO VOLTAGE
NOTE:
Make sure the Park Lamps are off when performing this step.
1. Turn the Park Lamps off.
2. Turn the ignition off.
3. Disconnect the Left Front Lamp Assembly harness connector.
4. Disconnect the Left Sidemarker Lamp Assembly harness connector.
5. Turn the ignition on.
6. Measure the voltage on the (L77) Left Front Park Lamp Driver circuit at the Left Front Lamp Assembly harness connector.
  Is there any voltage present?
  
  Yes
  - Repair the short to voltage in the (L77) Left Front Park Lamp Driver circuit.
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  No
  - Go To 3
CHECK THE (Z901) GROUND CIRCUITS FOR AN OPEN
1. Turn the ignition off.
2. Measure the resistance between ground and the (Z901) Ground circuit at the Left Front Lamp Assembly harness connector.
3. Measure the resistance between ground and the (Z901) Ground circuit at the Left Sidemarker Lamp Assembly harness connector.
  Is the resistance above 3.0 Ohms for any of the connections?
  
  Yes
  - Repair the open in the (Z901) Ground circuit(s).
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  No
  - Go To 4
CHECK THE BCM OUTPUT FOR CORRECT OPERATION
1. Turn the ignition on.
2. Turn the Park Lamps on.
  NOTE:
  The test light must illuminate brightly. Compare the brightness to that of a direct connection to the battery.
3. Connect a 12-volt test light between the (L77) Left Front Park Lamp Driver circuit and the (Z901) Ground circuit at the Left Front Lamp Assembly harness connector.
4. Connect a 12-volt test light between the (L77) Left Front Park Lamp Driver circuit and the (Z901) Ground circuit at the Left Sidemarker Lamp Assembly harness connector.
  Does the test light illuminate brightly for both connections?
  
  Yes
  - Replace the Left Front Sidemarker Lamp or Left Front Park Lamp in accordance with the Service Information. Refer to UNIT, FRONT LAMP, REMOVAL .
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  No
  - Go To 5
CHECK THE (L77) LEFT FRONT PARK LAMP DRIVER CIRCUIT FOR AN OPEN
1. Turn the Park Lamps off.
2. Turn the ignition off.
3. Disconnect the BCM C1/A harness connector.
4. Measure the resistance of the (L77) Left Front Park Lamp Driver circuit between the Left Front Lamp Assembly harness connector and the BCM C1/A harness connector.
5. Measure the resistance of the (L77) Left Front Park Lamp Driver circuit between the Left Sidemarker Lamp Assembly harness connector and the BCM C1/A harness connector.
  Is the resistance above 3.0 Ohms for any of the connections?
  
  Yes
  - Repair the open in the (L77) Left Front Park Lamp Driver circuit.
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  No
  - Replace the Body Control Module (BCM) in accordance with the Service Information. Refer to MODULE, BODY CONTROL (BCM), REMOVAL .
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .