P0643-SENSOR REFERENCE VOLTAGE 1 CIRCUIT HIGH
For a complete wiring diagram Refer to Section 8W
- When Monitored:
With the ignition on.
- Set Condition:
The PCM detects a short to voltage on the 5 volt supply circuit.
| Possible Causes |
| INTERMITTENT DTC |
| (K855) 5 VOLT SUPPLY CIRCUIT SHORTED TO VOLTAGE |
| (K856) 5 VOLT SUPPLY CIRCUIT SHORTED TO VOLTAGE |
| POWERTRAIN CONTROL MODULE (PCM) |
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
Diagnostic Test
1. DTC IS ACTIVEAttempt 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. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
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 (Refer to 9 - ENGINE - STANDARD PROCEDURE).
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 (Refer to 9 - ENGINE - STANDARD PROCEDURE).
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 (Refer to 9 - ENGINE - STANDARD PROCEDURE).
No
- Replace and program the Powertrain Control Module in accordance with the Service Information.
- Perform the PCM Verification Test Ver. 1 (Refer to 9 - ENGINE - STANDARD PROCEDURE).