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Diagnostic Procedure

  1. Install a scan tool. Does the scan tool power up? If so, go to next step. If not, diagnose scan tool concern. See appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.
  2. Turn ON the ignition, with the engine OFF. Attempt to establish communication with PCM and PZM. Does the scan tool communicate with both the PCM and PZM? If so, go to next step. If not, diagnose body control system. See appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.
    3. 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 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 next step. If not, diagnose body control system. See appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.
  4. With a scan tool, select the display DTC function for the PCM and the PZM. Does the scan tool display any DTCs? If so, go to next step. If not, attempt diagnosis by symptom. See SYMPTOM TESTS  .
  5. Does the scan tool display any DTCs which begin with a "U"? If so, diagnose body control system. See appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. If not, go to next step.
  6. Does the scan tool display DTC B1552, B1556 or B1558? If so, diagnose body control system. See appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. If not, go to next step.
  7. Does the scan tool display DTC P1820, P1822, P1823 or P1825? If so, diagnose engine control system. See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE. If only DTC B2502 or B2503 is displayed, see DIAGNOSTIC TROUBLE CODE DEFINITIONS  .
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