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Lighting Systems Diagnostic System Check

NOTE: The presence of DTCs which begin with "U" indicate some other module on class 2 serial data circuit is not communicating.
  1. Connect scan tool to Data Link Connector (DLC). DLC is located under left side of instrument panel. If scan tool powers up, go to next step. If scan tool does not power up, go to TEST A: SCAN TOOL DOES NOT POWER UP  under SYSTEM TESTS.
  2. Turn ignition switch to RUN position. Using scan tool, attempt to communicate with Body Control Module (BCM). If scan tool communicates with BCM, go to next step. If scan tool does not communicate with BCM, go to TEST B: SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE  under SYSTEM TESTS.
    3. NOTE: Engine may start during following step. Turn off engine as soon as crank power mode is observed.
  3. Using scan tool, access class 2 power mode from diagnostic circuit check function. Rotate ignition switch through all positions while observing ignition switch power mode parameter on scan tool. If ignition switch parameter reading matches ignition switch position for all switch positions, go to next step. If ignition switch parameter reading does not match ignition switch position for all switch positions, go to TEST C: POWER MODE MISMATCH  under SYSTEM TESTS.
  4. Using scan tool, select DISPLAY DTCS function and retrieve any BCM DTCs. If scan tool displays any DTCs, go to next step. If scan tool does not display any DTCs, repair lighting system by symptom. See appropriate EXTERIOR or INTERIOR LIGHTING article.
  5. If scan tool does not display any DTCs which begin with a "U", go to next step. If scan tool displays any DTCs which begin with a "U", go to TEST B: SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE  under SYSTEM TESTS.
  6. If scan tool does not display DTC B1000, go to next step. If scan tool displays DTC B1000, go to DTC B1000: BODY CONTROL MODULE MALFUNCTION  under DIAGNOSTIC TESTS.
  7. If scan tool displays DTC B1328, repair engine electrical concern. See appropriate GENERATOR & REGULATOR article in STARTING & CHARGING SYSTEMS. If scan tool displays any other DTCs, perform appropriate test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .
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