Captiva

DTC P0641 or P0651

The engine control module (ECM) has 2 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.

The ECM detects a voltage out of range condition on the 5 V reference 1 or 2 circuit for more than 0.5 s.

DTCs P0641 and P0651 are Type A DTCs.

DTCs P0641 and P0651 are Type A DTCs.

The 5 V reference 1 circuit provides 5 V to the following sensors:

The 5 V reference 2 circuit provides 5 V to the following sensors:

It may be possible to locate the fault by disconnecting one component at a time from the 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 Malfunction is still indicated, the fault may exist in the wiring harness.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

1. With the ignition ON and the engine OFF, observe the 5 V Reference 1 and 2 parameters. The scan tool should display 4.8-5.2 V for a normally operating system.
2. Ignition ON, observe the DTC information with a scan tool. DTCs P0641 and P0651 should not set.
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.

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, measure for 4.8-5.2 V between one of the 5 V reference circuits and ground.

⇒	If the voltage is less than the specified value, 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 value, 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 5 V reference circuit, one at a time, while monitoring the appropriate scan tool 5 V Reference Voltage parameter. Verify the voltage remains between 4.8-5.2 V.

⇒	If not the specified range 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.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.