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Home >> Jeep >> 2017 >> Wrangler Sahara, Automatic Trans >> Repair and Diagnosis >> External Pages >> Different car >> Section 14 (Body Control Module (BCM) - DTCS B106A-12 To B1A90-51) >> DTC Troubleshooting >> B1666-18-Left Reverse Lamp Control - Under Current >> Diagnostic Test

Diagnostic Test

WARNING: This page is about a different car, the 2017 Jeep Cherokee. However, it is still accessible from the selected car via links, so may be relevant.
  1. CHECK FOR AN ACTIVE DTC 
    1. Turn the ignition on.
    2. With the brakes firmly applied, shift the gear selector into REVERSE.
    3. With the scan tool, read DTCs.

      Does the scan tool display this DTC as active?

      Yes 

      • Go To  2

      No 

      • Test complete. 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.
      • Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  2. CHECK THE (L1) BACKUP LAMP DRIVER CIRCUIT FOR A SHORT TO VOLTAGE 
    1. Shift the gear selector into PARK.
    2. Turn the ignition off.
    3. Disconnect the Left and Right Liftgate Lamp harness connectors.
    4. Disconnect the BCM C6 harness connector.
    5. Turn the ignition on.
    6. Measure the voltage between ground and the (L1) Backup Lamp Driver circuit.

      Is there any voltage present?

      Yes 

      • Repair the short to voltage in the (L1) Backup Lamp Driver circuit.
      • Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .

      No 

      • Go To  3
  3. CHECK THE (L1) BACKUP LAMP DRIVER CIRCUIT FOR AN OPEN 
    1. Turn the ignition off.
    2. Measure the resistance of the (L1) Backup Lamp Driver circuit between the Left and Right Liftgate Lamp harness connectors and the BCM C6 harness connector.

      Is the resistance below 5.0 Ohms for both connections?

      Yes 

      • Go To  4

      No 

      • Repair the open in the (L1) Backup Lamp Driver circuit.
      • Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  4. CHECK THE (Z923) GROUND CIRCUIT FOR AN OPEN 
    1. Using a 12-volt test light connected to 12-volts, check the (Z923) Ground circuit.

      Does the test light illuminate brightly?

      Yes 

      • Go To  5

      No 

      • Repair the open in the (Z923) Ground circuit.
      • Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  5. CHECK THE BCM FOR CORRECT OPERATION 
    1. Turn the ignition off.
    2. Reconnect the BCM C6 harness connector.
    3. Connect a 12-volt test light between the (L1) Backup Lamp Driver circuit and the (Z923) Ground circuit at the Left and Right Liftgate Lamp harness connectors.
    4. Turn the ignition on.
    5. With the brakes firmly applied, shift the gear selector into REVERSE.

      Does the test light illuminate brightly at both connections?

      Yes 

      No