P0651
DTC P0641 or P0651
DTC Descriptors
DTC P0641
- 5-Volt Reference 1 Circuit
DTC P0651
- 5-Volt Reference 2 Circuit
Diagnostic Fault Information
Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
Circuit/System Description
The engine control module (ECM) has 2 5-volt reference circuits. The ECM provides the 5-volt reference to various sensors. Each reference circuit provides a 5-volt reference for more than one sensor. A short to ground or voltage on one of the 5-volt reference circuits will affect all components connected to that 5-volt reference circuit. The ECM monitors the voltage on the 5-volt reference circuits.
Conditions for Running the DTC
* The ignition is ON.
* DTCs P0641 and P0651 run continuously when the above condition is met.
Conditions for Setting the DTC
The control module detects a voltage above 5.5 volts, or below 4.5 volts, on either 5-volt reference circuit for more than 0.5 second.
Action Taken When the DTC Sets
DTCs P0641 and P0651 are Type B DTCs.
Conditions for Clearing the DTC
DTCs P0641 and P0651 are Type B DTCs.
Diagnostic Aids
The 5-volt reference 1 circuit provides 5 volts to the following sensors:
P0641
* The accelerator pedal position (APP) sensor 1
* The throttle position (TP) sensor 1
* The TP sensor 2
The 5-volt reference 2 circuit provides 5 volts to the following sensors:
P0651
* The APP sensor 2
* The air conditioning (A/C) refrigerant pressure sensor
* The exhaust gas recirculation (EGR) valve
* The fuel tank pressure (FTP) sensor
* The manifold absolute pressure (MAP) sensor
* The rough road sensor
Reference Information
Schematic Reference
Engine Controls Schematics Electrical Diagrams
Connector End View Reference
* Engine Control Module (ECM) Connector End Views Engine Control Module (ECM) Connector End Views
* Engine Controls Connector End Views Engine Controls Connector End Views
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
DTC Type Reference
Diagnostic Trouble Code (DTC) Type Definitions Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
* Scan Tool Data List Scan Tool Data List
* Scan Tool Data Definitions Scan Tool Data Definitions
* Scan Tool Output Controls Scan Tool Output Controls
Circuit/System Verification
1. Ignition ON, observe the DTC information with a scan tool. DTCs P0641 and P0651 should not set.
2. If the vehicle passes the Circuit/System Verification Test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records Data List.
Circuit/System Testing
Important: Additional DTCs will set when disconnecting the components.
1. Ignition OFF, disconnect the harness connector of all appropriate sensors for the applicable DTC. Refer to Diagnostic Aids.
2. Ignition ON, measure for 4.6-5.4 volts between one of the 5-volt reference circuits and ground.
• If the voltage is less than 4.6 volts, test for a short to ground on all the 5-volt reference circuits. If all circuits test normal, replace the control module.
Important: A short to voltage on the signal circuit of certain components may cause this DTC to set.
• If the voltage is greater than 5.4 volts, test for a short to voltage on all the 5-volt reference circuits, or the signal circuit, for each component associated with the appropriate 5-volt reference circuit. If all circuits test normal, replace the control module.
3. Connect each component associated with the 5-volt reference circuit one at a time while monitoring the voltage. The voltage should not change more than 0.5 volt.
• If the voltage display changes more than the specified value when a component is connected, replace the component.
Repair Instructions
Important: Always perform the Diagnostic Repair Verification Diagnostic Repair Verification after completing the diagnostic procedure.
* Accelerator Pedal with Position Sensor Replacement Service and Repair
* Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement Service and Repair
* Exhaust Gas Recirculation (EGR) Valve Replacement Exhaust Gas Recirculation (EGR) Valve Replacement
* Fuel Tank Pressure Sensor Replacement Service and Repair
* Manifold Absolute Pressure (MAP) Sensor Replacement Service and Repair
* Rough Road Sensor Replacement Service and Repair
* Throttle Body Assembly Replacement Removal and Replacement
* Control Module References Control Module References for ECM replacement, setup, and programming