Powertrain Management (ECM)
DTC P0641, P0651, P0697, or P06A3 (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 P0651
- 5 V Reference 2 Circuit
DTC P0697
- 5 V Reference 3 Circuit
DTC P06A3
- 5 V Reference 4 Circuit
Circuit/System Description
The engine control module (ECM) has 4 internal 5 V reference circuits. Each internal reference circuit provides external 5 V reference circuits for more than one sensor. A short to ground or short to voltage on one external 5 V reference circuit can affect all the components connected to the same internal 5 V reference circuit.
Conditions for Running the DTC
These DTCs run continuously when the ignition voltage is greater than 6.4 V.
Conditions for Setting the DTC
The ECM detects a voltage out of range condition on any of the 5 V reference circuits for greater than 0.5 s.
Action Taken When the DTC Sets
DTCs P0641, P0651, P0697, and P06A3 are Type A DTCs.
Conditions for Clearing the DTC
DTCs P0641, P0651, P0697, and P06A3 are Type A DTCs.
Diagnostic Aids
P0641
The 5 V reference 1 circuit provides 5 V circuits to the following sensors:
* Air conditioning (A/C) refrigerant pressure sensor
* Exhaust and intake camshaft position sensors
* Fuel tank pressure sensor
* Multifunction intake air sensor
P0651
The 5 V reference 2 circuit provides 5 V circuits to the following sensors:
* Brake pedal position sensor (automatic transmission)
* Clutch pedal position sensor (manual transmission)
* Crankshaft position sensor
* Secondary air injection pressure sensor, if equipped
* Vehicle speed sensor (manual transmission)
P0697
The 5 V reference 3 circuit provides 5 V circuits to the following sensors:
* Accelerator pedal position sensor 2
* Manifold absolute pressure sensor
P06A3
The 5 V reference 4 circuit provides 5 V circuits to the following sensors:
* Accelerator pedal position sensor 1
* Throttle position sensor 1 and 2
It may be possible to locate the fault by disconnecting one component at a time from the affected 5 V reference circuit 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 Fuel Pump and Level Sensor Assembly
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 Control Module References for scan tool information
Circuit/System Verification
1. Ignition ON.
2. Verify all scan tool 5 V Reference Circuit Status parameters do not display Malfunction.
• If any of the parameters display Malfunction
Refer to Circuit/System Testing
• If none of the parameters display Malfunction
3. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
4. Verify the DTC does not set.
• If the DTC sets
Refer to Circuit/System Testing
• If the DTC does not set
5. All OK.
Circuit/System Testing
Note: Additional DTCs will set when disconnecting the components.
1. Ignition OFF, disconnect the harness connector at all appropriate sensors for the applicable DTC. Refer to Diagnostic Aids.
2. Ignition ON.
3. Test for 4.8-5.2 V between one of the 5 V reference circuits and ground.
• If less than 4.8 V
1. Ignition OFF, disconnect the harness connectors at the K20 Engine Control Module.
2. Test for infinite resistance between the 5 V reference circuit for each applicable component and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, replace the K20 Engine Control Module.
• If greater than 5.2 V
1. Ignition OFF, disconnect the harness connectors at the K20 Engine Control Module.
2. Test for less than 1 V between the 5 V reference circuit for each applicable component and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K20 Engine Control Module.
• If between 4.8-5.2 V
Note: A short to voltage or ground on the signal circuit of certain components may cause this DTC to set.
4. Verify the appropriate scan tool 5 V Reference 1, 2, 3, or 4 Circuit Status parameter displays OK while connecting each component associated with the 5 V reference circuit one at a time.
• If the parameter does not display OK when a component is connected
Replace the component
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Accelerator Pedal Position Sensor Replacement Service and Repair
* Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement (LDE/LUW) Service and RepairAir Conditioning (A/C) Refrigerant Pressure Sensor Replacement (LUV) Service and Repair
* Brake Pedal Position Sensor Replacement Service and Repair
* Camshaft Position Sensor Replacement Service and Repair
* Clutch Pedal Position Sensor Replacement Service and Repair
* Crankshaft Position Sensor Replacement Service and Repair
* Fuel Tank Pressure Sensor Replacement Service and Repair
* Manifold Absolute Pressure Sensor Replacement Service and Repair
* Mass Airflow Sensor Replacement Service and Repair
* Secondary Air Injection Check Valve Replacement Service and Repair
* Throttle Body Assembly Replacement Removal and Replacement
* Vehicle Speed Sensor Replacement Service and Repair
* Control Module References Control Module References for engine control module replacement, programming, and setup