P0641

P0641-SENSOR REFERENCE VOLTAGE 1 CIRCUIT

For a complete wiring diagram, refer to the Wiring Information.

Theory of Operation

The Powertrain Control Module (PCM) contains 3 internal 5-Volt Sensor Supply sources. Each 5-Volt Supply source is split into parallel circuits to provide 5.0 Volts to multiple sensors.

- When Monitored:
With the ignition on.

- Set Condition:
The Powertrain Control Module (PCM) detects a short to voltage or short to groune on the 5-Volt Sensor Supply 1 circuit 0.6 seconds.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

Diagnostic Test

1. CHECK FOR ACTIVE DTC
1. Turn the ignition on.
2. With the scan tool, erase PCM DTCs.
3. Turn the ignition off for 10 seconds.
4. Turn the ignition on.
5. With the scan tool, View DTCs.

Is the status Active for this DTC?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test.

2. CHECK THE THROTTLE POSITION SENSOR
1. Turn the ignition off.
2. Disconnect the Throttle Body harness connector.
3. Turn the ignition on.
4. Measure the voltage on the (F855) 5-Volt Supply circuit at the Throttle Body harness connector.

Is the voltage between 4.8 and 5.2 Volts?

Yes

- Replace the Throttle Body.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 2

3. CHECK THE FUEL TANK PRESSURE SENSOR
1. Turn the ignition off.
2. Disconnect the Fuel Tank Pressure Sensor harness connector.
3. Turn the ignition on.
4. Measure the voltage on the (N8) 5-Volt Supply circuit at the Fuel Tank Pressure Sensor harness connector.

Is the voltage between 4.8 and 5.2 Volts?

Yes

- Replace the Fuel Tank Pressure Sensor.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 4

4. CHECK THE APP SENSOR 1
1. Turn the ignition off.
2. Disconnect the APP Sensor harness connector.
3. Turn the ignition on.
4. Measure the voltage on the (K852) 5-Volt Supply circuit at this Sensor harness connector.

Is the voltage between 4.8 and 5.2 Volts for each sensor?

Yes

- Replace the APP Sensor.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No, voltage is below 4.8 volts,

- Go To 5

No, voltage measured above 5.2 volts on one of the 5-Volt Supply circuits,

- Repair the 5-Volt Supply circuit for a short to voltage.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

5. CHECK THE 5-VOLT SUPPLY CIRCUITS FOR A SHORT TO GROUND
1. Turn the ignition off.
2. Disconnect the PCM harness connectors.
3. Measure the resistance between ground and each of the 5-Volt Supply circuit at the PCM harness connector.

Is the resistance above 10k Ohms for each 5-Volt Supply circuit?

Yes

- Go To 6

No

- Repair the 5-Volt Supply circuit that measured below 10k Ohms for a short to ground.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

6. POWERTRAIN CONTROL MODULE
1. Turn the ignition off.
2. Look for any chafed, pierced, pinched, or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals.
4. Perform any Technical Service Bulletins that may apply.

Were any problems found?

Yes

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

No

- Replace the Powertrain Control Module (PCM). .
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.