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Engine Electrical Diagnostic System Check

  1. Perform the Battery Inspection/Test. See BATTERY TESTING & INSPECTION in GENERATORS & REGULATORS article. 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, see SCAN TOOL POWER UP 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 Class 2 Power Mode in the Diagnostic Circuit Check on the scan tool. Rotate the ignition switch through all positions while observing the Class 2 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, see COMMUNICATION DEVICES article in ACCESSORIES & EQUIPMENT.
  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 any module on the class 2 serial data circuit? If so, go to step  5. If not, see COMMUNICATION DEVICES article in ACCESSORIES & EQUIPMENT.
  5. 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. 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, see SYMPTOM INDEX .
  6. Does the scan tool display any DTCs which begin with a "U"? If so, see COMMUNICATION DEVICES article in ACCESSORIES & EQUIPMENT. If not, go to step  7.
  7. Does the scan tool display DTC B1000? If so, see DTC P0560: THE PCM DETECTS A SYSTEM VOLTAGE OUT OF RANGE FOR 30 SECONDS  and/or DTC P0620: THE GENERATOR TURN ON SIGNAL CIRCUIT VOLTAGE LOW WHILE THE PCM IS COMMANDING GENERATOR ON, CONDITION PRESENT FOR MORE THAN 30 SECONDS  . If not, see SELF-DIAGNOSTICS article in FAULT ISOLATION under ENGINE PERFORMANCE.
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