Diesel

P0643-SENSOR REFERENCE VOLTAGE 1 CIRCUIT HIGH





For a complete wiring diagram Consult Diagrams/Electrical

- When Monitored:
With the ignition on.

- Set Condition:
The ECM detects a short to voltage on the Sensor Supply #1 circuit for 0.10 seconds.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.Initial Inspection and Diagnostic Overview

Theory of Operation

The ECM contains 3 internal 5-Volt Sensor Supply sources. Each 5-Volt Supply source is split into parallel circuits to provide 5 volts to multiple sensors. Sensor Supply 1 provides 5 volts to the Camshaft Position Sensor and the Accelerator Pedal Position Sensor #1.

Diagnostic Test

1. CHECK FOR ACTIVE DTC
Turn the ignition on.
With the scan tool, erase ECM DTCs.
Turn the ignition off for 10 seconds.
Turn the ignition on.
With the scan tool, View DTCs.
Is the status Active for this DTC?

Yes

- Go To2

No

- Refer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure.Intermittent Condition

2. (F855) ACCELERATOR PEDAL POSITION SENSOR NO.1 5-VOLT SUPPLY CIRCUIT SHORTED TO VOLTAGE




Turn the ignition off.
Disconnect the Accelerator Pedal Position Sensor harness connector.
Disconnect the ECM harness connectors.
Remove the ASD Relay from the PDC.
Connect a jumper wire between cavity 30 and cavity 87 of the ASD Relay connector.
Turn the ignition on.
Measure the voltage on the (F855) Accelerator Pedal Position Sensor No. 1 5 Volt Supply circuit.
Is the voltage below 1.0 volt?

Yes

- Go To3

No

- Repair the (F855) Accelerator Pedal Position Sensor No. 1 5 Volt Supply circuit for a short to voltage.
- Perform the ECM VERIFICATION TESTVerification Tests

3. (K844) CAMSHAFT POSITION SENSOR 5-VOLT SUPPLY CIRCUIT SHORTED TO VOLTAGE




Turn the ignition off.
Disconnect the Camshaft Position Sensor harness connector.

NOTE: The jumper wire should still be in place.

Turn the ignition on.
Measure the voltage on the (K844) Camshaft Position Sensor 5 Volt Supply circuit.
Is the voltage below 1.0 volt?

Yes

- Go To4

No

- Repair the (K844) Camshaft Position Sensor 5 Volt Supply circuit for a short to voltage.
- Perform the ECM VERIFICATION TESTVerification Tests

4. ENGINE CONTROL MODULE (ECM)
Turn the ignition off.
Inspect the (K844) Camshaft Position Sensor 5 Volt Supply circuit between the CMP harness connector and the ECM harness connector.
Inspect the (F855) Accelerator Pedal Position Sensor No. 1 5 Volt Supply circuit between the APP Sensor harness connector and the ECM harness connector
Look for any chafed, pierced, pinched, or partially broken wires.
Look for broken, bent, pushed out or corroded terminals.
Monitor the scan tool data relative to this circuit and wiggle test the wiring and connectors.
Look for the data to change or for the DTC to reset during the wiggle test.
Search for any Technical Service Bulletins that may apply.
Were any problems found?

Yes

- Repair as necessary.
- Perform the ECM VERIFICATION TESTVerification Tests

No

- Replace and program the Engine Control Module.
- Perform the ECM VERIFICATION TESTVerification Tests