DTC P0641, P0651, P0697, or P06A3 (ECM)

Diagnostic Instructions

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

Circuit/System Description

The engine control module (ECM) has 4 internal 5V reference circuits. Each internal reference circuit provides an external 5V reference circuit for more than one sensor. A short to ground or short to voltage on one of the external 5V reference circuits can affect all the components connected to the same internal 5V reference circuit.

Conditions for Running the DTC

These DTCs run continuously when 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, 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 5V reference 1 circuit provides 5 V to the sensors listed below:

  • A/C refrigerant pressure sensor
  • All four camshaft position sensors
  • Fuel pressure sensor
  • Fuel rail pressure sensor
  • Fuel tank pressure sensor
  • Multifunction intake air sensor

P0651

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

  • Brake pedal position sensor
  • Crankshaft position sensor
  • Fuel economy mode switch

P0697

The 5V reference 3 circuit provides 5 V to the sensors listed below:

  • Manifold absolute pressure sensor
  • Accelerator pedal position sensor 2

P06A3

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

  • Throttle position sensor
  • Accelerator pedal position sensor 1

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 Schematics

Connector End View Reference

Component Connector End Views

Component View Reference

Powertrain Component Views

Electrical Information ReferenceDTC 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 all scan tool 5V Reference Circuit Status parameters do not display Malfunction.
    • If Malfunction is displayed

      Refer to Circuit/System Testing.

    • 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.

    • 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.
    • 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, or 4 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 that component for a short to ground or voltage. If the circuit tests normal, replace the component.

    • If OK is displayed after all components have been connected
  5. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.