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Diagnostic System Check (Engine Electrical)

  1. Perform the Battery Inspection/Test. See BATTERY TESTING & INSPECTION under ON-VEHICLE TESTING in STARTING & CHARGING SYSTEMS under CHARGING SYSTEMS in ELECTRICAL. Does the battery pass the test? If so, go to step  2 .
  2. Install a scan tool. Turn ON the ignition, with the engine OFF. Does the scan tool power up? If so, go to step  3 . If not, go to appropriate BODY CONTROL MODULES article under COMMUNICATION DEVICES in ACCESSORIES & EQUIPMENT.
    3. CAUTION: The engine may start during the following step. Turn OFF the engine as soon as you have observed the Crank power mode.
  3. Access the Ignition Switch parameter in the body control module (BCM) inputs data display list. Rotate the ignition switch through all positions while observing the ignition switch power mode parameter. Does the ignition switch parameter reading match the ignition switch position for all switch positions? If so, go to step  4 . If not, go to appropriate BODY CONTROL MODULES article under COMMUNICATION DEVICES in ACCESSORIES & EQUIPMENT.
    4. NOTE: Lack of communication may be because of a partial malfunction of the class 2 serial data circuit or due to a total malfunction of the class 2 serial data circuit. The specified procedure will determine the particular condition.
  4. Turn ON the ignition, with the engine OFF. Attempt to communicate with each of the following modules on the class 2 serial data circuit: Body Control Module (BCM), Instrument Panel Cluster (IPC) and Powertrain Control Module (PCM). Does the scan tool communicate with all modules on the class 2 serial data circuit? If so, go to step  5 . If not, go to appropriate BODY CONTROL MODULES article under COMMUNICATION DEVICES in ACCESSORIES & EQUIPMENT.
    5. NOTE: The symptom list in system tests will determine the correct diagnostic procedure to use. See SYMPTOM INDEX  table under SYSTEM TESTS.
  5. Select the Display DTCs function for the BCM, IPC, and PCM. Record all of the displayed DTCs, the DTC status, and the module which set the DTC. Does the scan tool display any DTCs? If so, go to step  6 . If not, go to SYMPTOM INDEX  table under SYSTEM TESTS.
    6. NOTE: The presence of DTCs which begin with a "U" indicate some other module is not communicating. The specified procedure will collect all the available information before you perform tests.
  6. Does the scan tool display any DTCs which begin with a "U"? Go to appropriate BODY CONTROL MODULES article under COMMUNICATION DEVICES in ACCESSORIES & EQUIPMENT. If not, go to step  7 .
  7. Does the scan tool display DTC B1000, B1004, B1007, or B1009? If so, go to appropriate BODY CONTROL MODULES article under COMMUNICATION DEVICES in ACCESSORIES & EQUIPMENT. If not, go to DIAGNOSTIC TESTS  .
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