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Engine Electrical Diagnostic System Check

  1. Did you perform the Battery Inspection/Test? If so, go to next step. If not, go to BATTERY TESTING & INSPECTION (NON-HP2)  .
  2. Install a scan tool. Does the scan tool power up? If so, go to step  4 . If not, see SCAN TOOL DOES NOT POWER UP in BODY CONTROL MODULES .
    NOTE: 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 Class 2 Power Mode in the Diagnostic Circuit Check on the scan tool. Rotate the ignition switch through OFF, RUN, and CRANK positions while observing the ignition switch power mode parameter. Does the ignition switch parameter reading match the ignition switch positions for OFF, RUN and CRANK positions? If so, go to next step. If not, see POWER MODE MISMATCH in BODY CONTROL MODULES .
  4. Lack of communication may be due to 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.
    1. Turn ON the ignition, with the engine OFF.
    2. Attempt to communicate with each module on the class 2 serial data circuit.
      • Body Control Module (BCM)
      • Driver Information Center (DIC)
      • Instrument Panel Cluster (IPC)
      • Powertrain Control Module (PCM)
    Does the scan tool communicate with any module on the class 2 serial data circuit? If so, go to next step. If not, see SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE in BODY CONTROL MODULES .
  5. The symptom list in Symptoms will determine the correct diagnostic procedure to use.
    1. Select the Display DTCs function for each module. (If using a Tech 2, use the Class 2 DTC Check feature in order to determine which modules have DTCs set.)
    2. 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 next step. If not, go to ENGINE ELECTRICAL SYMPTOMS  .
  6. The presence of DTCs which begin with "U" indicate some other module is not communicating. The specified procedure will compile all the available information before tests are performed. Does the scan tool display any DTC beginning with "U"? If so, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If not, go to next step
  7. Does the scan tool display any DTC beginning with "B"? If so, see DIAGNOSTIC TROUBLE CODE DEFINITIONS in BODY CONTROL MODULES . If not, see DIAGNOSTIC TROUBLE CODE DEFINITIONS .
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