P0643

P0643-SENSOR REFERENCE VOLTAGE 1 CIRCUIT HIGH





For a complete wiring diagram refer to Diagrams/Electrical.

- When Monitored:

With the ignition on.

- Set Condition:

The PCM detects a short to voltage on the 5 volt supply circuit.






Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.

Diagnostic Test

1. DTC IS ACTIVE

Attempt to start the engine. If the engine will not start, crank the engine for 5 seconds.

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.

With the scan tool, select View DTCs.

Is the status Active for this DTC?

Yes

- Go to2

No

- Refer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure. Checking for an Intermittent DTC

2. (K856) 5 VOLT SUPPLY CIRCUIT SHORTED TO VOLTAGE

Turn the ignition off.

Disconnect the Accelerator Pedal Position Sensor harness connector.

Disconnect the PCM harness connectors.

Measure the voltage on the (K856) 5 Volt Supply circuit.

Is there any voltage present?

Yes

- Repair the (K856) 5 Volt Supply circuit for a short to voltage.
- Perform the PCM Verification Test Ver. 1. PCM Verification Test

No

- Go to3

3. (K855) 5 VOLT SUPPLY CIRCUIT SHORTED TO VOLTAGE

Turn the ignition off.

Disconnect the Throttle Body harness connector.

Turn the ignition on.

Measure the voltage on the (K855) 5 Volt Supply circuit.

Is there any voltage present?

Yes

- Repair the (K855) 5 Volt Supply circuit for a short to voltage.
- Perform the PCM Verification Test Ver. 1. PCM Verification Test

No

- Go to4

4. POWERTRAIN CONTROL MODULE (PCM)

Turn the ignition off.

Inspect the (K855) 5 Volt Supply circuit between the Camshaft 1/2 Position Sensor harness connector and the PCM harness connector.

Inspect the (K855) 5 Volt Supply circuit between the Crankshaft Position Sensor harness connector and the PCM harness connector.

Inspect the (K855) 5 Volt Supply circuit between the Throttle Body harness connector and the PCM harness connector.

Inspect the (K856) 5 Volt Supply circuit between the Accelerator Pedal Position Sensor harness connector and the PCM harness connector.

If the vehicle is equipped with a manual transmission, inspect the (K856) 5 Volt Supply circuit between the Vehicle Speed Sensor harness connector and the PCM harness connector.

Look for any chafed, pierced, pinched, or partially broken wires.

Look for broken, bent, pushed out or corroded terminals.

Refer to any Technical Service Bulletins that may apply.

Were any problems found?

Yes

- Repair as necessary.
- Perform the PCM Verification Test Ver. 1. PCM Verification Test

No

- Replace and program the Powertrain Control Module.
- Perform the PCM Verification Test Ver. 1. PCM Verification Test