Check VPWR During Cranking

Purpose:
To verify PCM power-up during cranking. Lack of power to PCM can cause a no start condition as well as fault code loss. Scan tools often require a minimum system voltage of 9.5 volts to avoid resetting.

Recommended Procedure:
Connect the OBDII Scan Tool to the data link connector (DLC) under the dash. Access VPWR PID on OBDII Scan tool and monitor while cranking the engine.

Possible Causes:

  • Low battery voltage.
  • Charging system problem.
  • Power circuit and ground faults to the PCM.
     

Note: Battery voltage below 9.5 volts can cause the Sacn tool to reset. If the OBDII Scan Tool resets during a self test or while PID monitoring, it may be necessary to install a battery charger to maintain the correct voltage.

Tools Required:
Rotunda New Generation Star (NGS) Tester 007-00500 or equivalent Scan Tool.