P0651
DTC P0641-P0643, P0651-P0653, or P0697-P0699 (ECM)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.
DTC Descriptors
DTC P0641
- 5 V Reference 1 Circuit
DTC P0642
- 5 V Reference 1 Circuit Low Voltage
DTC P0643
- 5 V Reference 1 Circuit High Voltage
DTC P0651
- 5 V Reference 2 Circuit
DTC P0652
- 5 V Reference 2 Circuit Low Voltage
DTC P0653
- 5 V Reference 2 Circuit High Voltage
DTC P0697
- 5 V Reference 3 Circuit
DTC P0698
- 5 V Reference 3 Circuit Low Voltage
DTC P0699
- 5 V Reference 3 Circuit High Voltage
Circuit/System Description
The engine control module (ECM) has 3 internal 5 V reference circuits. Each internal reference circuit provides a 5 V reference for more than one sensor. A short to ground or short to voltage on one of the external 5 V reference circuits can affect all the components connected to the same internal 5 V reference circuit.
Conditions for Running the DTC
* The ignition is ON for greater than 3 s.
* DTCs P0641, P0642, P0643, P0651, P0652, P0653, P0697, P0698, and P0699 run continuously when the above condition is met.
Conditions for Setting the DTC
The 5 V reference circuit voltage is greater or less than a predetermined threshold.
Action Taken When the DTC Sets
DTCs P0641, P0642, P0643, P0651, P0652, P0653, P0697, P0698, and P0699 are Type A DTCs.
Conditions for Clearing the DTC
DTCs P0641, P0642, P0643, P0651, P0652, P0653, P0697, P0698, and P0699 are Type A DTCs.
Diagnostic Aids
DTC P0641, P0642, and P0643
The 5 V reference 1 circuit provides 5 V to the following sensors:
* Fuel tank pressure (FTP) sensor
* Engine oil pressure (EOP) sensor
* Fuel rail pressure (FRP) sensor
* Clutch pedal position sensor, if equipped
DTC P0651, P0652, and P0653
The 5 V reference 2 circuit provides 5 V to the following sensors:
* All four camshaft position (CMP) sensors
* Accelerator pedal position (APP) sensor 1
DTC P0697, P0698, and P0699
The 5 V reference 3 circuit provides 5 V to the following sensors:
* Throttle position sensor (TP) 1 and 2
* Crankshaft position (CKP) sensor
* Accelerator pedal position (APP) sensor 2
* A/C refrigerant pressure sensor
It may be possible to locate the fault by disconnecting one component at a time from the affected 5 V reference bus while viewing the 5 V Reference Circuit Status parameter on the scan tool. The scan tool parameter will change from Malfunction to OK when the source of the fault is disconnected. If all 5 V reference components have been disconnected and a fault is still indicated, the fault may exist in the wiring harness.
Reference Information
Schematic Reference
Engine Controls Schematics ([1][2]Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector End Views By Name)
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
Control Module References (Programming and Relearning) for scan tool information
Circuit/System Verification
1. Ignition ON, observe the DTC information with a scan tool. DTC P0641, P0642, P0643, P0651, P0652, P0653, P0697, P0698, or P0699 should not set.
2. Observe the appropriate scan tool 5 V Reference Circuit Test Status parameter. The parameter should display OK.
3. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing
Note: 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, test for 4.8-5.2 V between one of the affected 5 V reference circuits and ground.
• If the voltage is less than the specified range, test for a short to ground on the 5 V reference circuit for each affected component. If all circuits test normal, replace the K20 ECM.
• If the voltage is greater than the specified range, test for a short to voltage on the 5 V reference circuit for each affected component. If all circuits test normal, replace the K20 ECM.
Note: A short to voltage on the signal circuit of certain components may cause this DTC to set.
3. Connect each component associated with the affected 5 V reference circuit one at a time while monitoring the appropriate scan tool 5 V Reference Circuit Status parameter. The parameter should continue to display OK.
• If the parameter displays Malfunction when a component is connected, test the signal circuit of that component for a short to voltage. If the circuit tests normal, 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 (LLT) (Service and Repair)Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement (LS3, L99) (Service and Repair)
* Camshaft Position Sensor Replacement - Bank 1 (Right Side) Intake (Camshaft Position Sensor Replacement - Bank 1 (Right Side) Intake)
* Camshaft Position Sensor Replacement - Bank 1 (Right Side) Exhaust (Camshaft Position Sensor Replacement - Bank 1 (Right Side) Exhaust)
* Camshaft Position Sensor Replacement - Bank 2 (Left Side) Intake (Camshaft Position Sensor Replacement - Bank 2 (Left Side) Intake)
* Camshaft Position Sensor Replacement - Bank 2 (Left Side) Exhaust (Camshaft Position Sensor Replacement - Bank 2 (Left Side) Exhaust)
* Clutch Pedal Position Sensor Replacement (Service and Repair)
* Crankshaft Position Sensor Replacement (Service and Repair)
* Engine Oil Pressure Sensor and/or Switch Replacement (LCS) (Service and Repair)
* Fuel Pressure Sensor Replacement - Fuel Injection Fuel Rail (Fuel Pressure Sensor Replacement - Fuel Injection Fuel Rail)
* Fuel Tank Pressure Sensor Replacement (Service and Repair)
* Throttle Body Assembly Replacement (Removal and Replacement)
* Control Module References (Programming and Relearning) for engine control module replacement, setup, and programming