15. Check Vehicle Power (VPWR) During Cranking Test

15. CHECK VEHICLE POWER (VPWR) DURING CRANKING TEST

Purpose:
The purpose of this test is to verify PCM power during cranking.

Scan Tool - Data List Monitoring

NOTE:
- The 8 volt specification represents the minimum battery voltage required for engine starting. Greater than average crank times are encountered if the battery voltage is less than 9.5 volts. If excessive crank time is a concern, verify battery voltage is greater than 9.5 volts.
- An outside power source may be needed for the scan tool.

- The scan tool may reset below 9.5 volts.
- Select the parameters indicated from the scan tool parameter list and monitor while cranking the engine.







If a low voltage condition is present, check the battery, charging system or power and ground circuits to the PCM.

Recommended Procedure:
- Connect the scan tool.
- Ignition ON, engine OFF.
- Access and monitor the VPWR PID while cranking the engine.

Possible Causes:
- Battery cables
- Low battery voltage
- Charging system
- Power and ground circuits to the PCM
- PCM relay

GO to Pinpoint Test A to diagnose a voltage concern. Test A: Powertrain Control Module (PCM) Power Relay

Tools Required:
Scan tool