Buick Regal Owners & Service Manuals

Buick Regal: DTC P0641, P0651, P0697, P06A3, or P06D2

Diagnostic Instructions

  • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
  • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
  • Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P0641

5V Reference 1 Circuit

DTC P0651

5V Reference 2 Circuit

DTC P0697

5V Reference 3 Circuit

DTC P06A3

5V Reference 4 Circuit

DTC P06D2

5V Reference 5 Circuit

Circuit/System Description

The engine control module (ECM) has 5 internal 5V reference circuits. Each internal reference circuit provides external 5V reference circuits for one or more sensors. A short to ground or short to voltage on one external 5V reference circuit can affect all the components connected to the same internal 5V 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 short to ground or voltage on any of the 5V reference circuits for greater than 0.5 s.

Action Taken When the DTC Sets

DTCs P0641, P0651, P0697, P06A3, and P06D2 are Type A DTCs.

Conditions for Clearing the DTC

DTCs P0641, P0651, P0697, P06A3, and P06D2 are Type A DTCs.

Diagnostic Aids

The 5V reference 1 circuit provides 5 V to the components listed below:

  • Air conditioning (A/C) refrigerant pressure sensor
  • Center console multifunction switch
  • Exhaust and intake camshaft position sensors
  • Fuel pressure sensor
  • Manifold absolute pressure sensor

The 5V reference 2 circuit provides 5 V to the sensors listed below:

  • Brake booster vacuum sensor
  • Brake pedal position sensor
  • Crankshaft position sensor
  • Engine oil pressure sensor
  • Turbocharger boost/intake air temperature sensor

The 5V reference 3 circuit provides 5 V to the accelerator pedal position sensor 2.

The 5V reference 4 circuit provides 5 V to the sensors listed below:

  • Accelerator pedal position sensor 1
  • Throttle position sensor

The 5V reference 5 circuit provides 5 V to the sensors listed below:

  • Fuel rail pressure sensor
  • Multifunction intake air sensor

Disconnecting one component at a time from the affected 5V reference circuit while observing the scan tool 5V Reference Circuit Status parameter may help locate the fault. The scan tool parameter will change from Malfunction to OK when the source of the fault is disconnected. If all 5V 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 Wiring Schematics (LTG)

Connector End View Reference

Component Connector End View Index

Component View Reference

Powertrain Component Views

Electrical Information Reference

  • Circuit Testing
  • Connector Repairs
  • Testing for Intermittent Conditions and Poor Connections
  • Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Ignition ON.

2. Verify scan tool 5V Reference 1-5 Circuit Status parameters do not display Malfunction.

  • If Malfunction is displayed

Refer to Circuit/System Testing.

  • Go to next step: If Malfunction is not displayed

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.

  • Go to next step: 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 5V 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 5V 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 5V 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.
  • Go to next step: 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 5V Reference 1, 2, 3, 4, or 5 Circuit Status parameter displays OK while connecting each component associated with the 5V reference circuit one at a time.

  • If OK is not displayed when a component is connected

Test the signal circuit of the component for a short to ground or voltage. If the circuit tests normal, replace the component.

  • Go to next step: If OK is displayed after all components have been connected

5. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

  • Accelerator Pedal with Position Sensor Assembly Replacement
  • Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement
  • Brake Pedal Position Sensor Replacement
  • Camshaft Position Sensor Replacement - Exhaust
  • Camshaft Position Sensor Replacement - Intake
  • Crankshaft Position Sensor Replacement
  • Engine Oil Pressure Sensor Replacement
  • Fuel Injection Fuel Rail Fuel Pressure Sensor Replacement
  • Fuel Pressure Sensor Replacement - Fuel Feed Pipe (AWD) or Fuel Pressure Sensor Replacement - Fuel Feed Pipe (FWD)
  • Intake Air Pressure and Temperature Sensor Replacement for turbocharger boost/intake air temperature sensor replacement.
  • Manifold Absolute Pressure Sensor Replacement
  • Mass Airflow Sensor with Intake Air Temperature Sensor Replacement for multifunction intake air sensor replacement.
  • Throttle Body Assembly Replacement
  • Control Module References for engine control module replacement, programming, and setup.

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