P0641
DTC P0641 or P0651
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Strategy Based Diagnosis Strategy Based Diagnosis
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions
DTC Descriptors
DTC P0641
- 5-Volt Reference 1 Circuit
DTC P0651
- 5-Volt Reference 2 Circuit
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.
* The ECM commands the TAC system to operate in a Reduced Engine Power mode.
Conditions for Clearing the DTC
DTCs P0641 and P0651 are Type B DTCs.
Diagnostic Aids
* If a shared 5-volt reference circuit is shorted to ground or shorted to a voltage, other 5-volt reference circuits may be affected.
* The scan tool 5-volt reference parameter should display between 4.8-5.2 volts.
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 throttle position (TP) sensor 2
The 5-volt reference 2 circuit provides 5 volts to the following sensors:
P0651
* The accelerator pedal position (APP) sensor 2
* The air conditioning (A/C) refrigerant pressure sensor
* The exhaust gas recirculation (EGR) valve
* The fuel tank pressure (FTP) sensor
* The rough road sensor
Reference Information
Schematic Reference
Engine Controls Schematics (w/Throttle Actuator Controls) Electrical DiagramsEngine Controls Schematics (w/o Throttle Actuator Control) Electrical Diagrams
Connector End View Reference
* Engine Control Module Connector End Views (w/ Throttle Actuator Control) Engine Control Module Connector End Views (w/ Throttle Actuator Control)Engine Control Module Connector End Views (w/o Throttle Actuator Control) Engine Control Module Connector End Views (w/o Throttle Actuator Control)
* Engine Controls Connector End Views (w/ Throttle Actuator Control) Engine Controls Connector End Views (w/ Throttle Actuator Control)Engine Controls Connector End Views (w/o Throttle Actuator Control) Engine Controls Connector End Views (w/o Throttle Actuator Control)
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
Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
* Scan Tool Data List (w/ Throttle Actuator Control) Scan Tool Data List (w/ Throttle Actuator Control)Scan Tool Data List (w/o Throttle Actuator Control) Scan Tool Data List (w/o Throttle Actuator Control)
* Scan Tool Data Definitions (w/ Throttle Actuator Control) Scan Tool Data Definitions (w/ Throttle Actuator Control)Scan Tool Data Definitions (w/o Throttle Actuator Control) Scan Tool Data Definitions (w/o Throttle Actuator Control)
* Scan Tool Output Controls (w/ Throttle Actuator Control) Scan Tool Output Controls (w/ Throttle Actuator Control)Scan Tool Output Controls (w/o Throttle Actuator Control) Scan Tool Output Controls (w/o Throttle Actuator Control)
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 the specified range, test for a short to ground on all the 5-volt reference circuits. If all circuits test normal, replace the control module.
• If the voltage is greater than the specified range, test for a short to voltage on all the 5-volt reference circuits for each component associated with the appropriate 5-volt reference circuit. 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.
3. Connect each component associated with the 5-volt reference circuit one at a time while monitoring the scan tool 5-volt reference voltage parameter. The voltage should not change more than 0.5 volt.
• If the voltage display increases more than the specified value when a component is connected, test the signal circuit for a short to voltage. If all circuits test normal, replace the control module.
• If the voltage display decreases more than the specified value when a component is connected, replace the component.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Accelerator Pedal Position Sensor Replacement Service and Repair
* Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement Service and Repair
* Exhaust Gas Recirculation Valve Replacement Service and Repair
* Fuel Tank Pressure Sensor Replacement Service and Repair
* Manifold Absolute Pressure 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