P0643

P0643-PRIMARY 5-VOLT SUPPLY CIRCUIT HIGH





For a complete wiring diagram refer to Diagrams/Electrical.

- When Monitored:

Ignition on.

- Set Condition:

When the PCM recognizes the Primary 5-volt Supply circuit voltage is too high. One Trip Fault. ETC light is flashing.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.

Diagnostic Test

1. ACTIVE DTC

Ignition on, engine not running.

With a scan tool, select View DTCs.

Is the DTC Active at this time?

Yes

- Go To 2

No

- Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Intermittent Condition
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

2. (F855) PRIMARY 5-VOLT SUPPLY SHORTED TO BATTERY VOLTAGE





Turn the ignition off.

Disconnect the C2 PCM harness connector.

Disconnect all the Sensors that share the (F855) Primary 5-volt Supply circuit.

NOTE: Improperly installed aftermarket accessories can cause this DTC to set. Check for wiring added by customer.

Ignition on, engine not running.

Measure the voltage on the (F855) Primary 5-volt Supply circuit at the CKP Sensor harness connector.

Is the voltage above 5.2 volts?

Yes

- Repair the short to battery voltage in the (F855) Primary 5-volt Supply circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

No

- Go To 3

3. PCM

NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.

Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.

Were there any problems found?

Yes

- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

No

- Replace and program the Powertrain Control Module.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test