Buick Regal: DTC P0650, P263A, or P263B

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 Descriptor

DTC P0650

Malfunction Indicator Lamp (MIL) Control Circuit Open

DTC P263A

Malfunction Indicator Lamp (MIL) Control Circuit Low Voltage

DTC P263B

Malfunction Indicator Lamp (MIL) Control Circuit High Voltage

Diagnostic Fault Information

Circuit/System Description

The malfunction indicator lamp (MIL) illuminates to inform the driver that an emission system fault has occurred and the powertrain control system requires service. Ignition voltage is supplied directly to the MIL. The engine control module (ECM) turns the MIL ON by grounding the MIL control circuit when the emission system fault occurs. Under normal operating conditions, the MIL should be ON only when the ignition is ON and the engine is OFF.

Conditions for Running the DTC

• The engine speed is greater than 80 RPM.
• The ignition voltage is between 11 - 32 V.
• The DTCs run continuously when the above conditions are met.

Conditions for Setting the DTC

DTC P0650 or DTC P263A

The ECM detects low voltage during the MIL control circuit driver OFF state. This indicates either a shorted to ground or an open MIL control circuit.

DTC P263B

The ECM detects high voltage on the MIL control circuit during the driver ON state. This indicates a shorted to voltage MIL control circuit.

Action Taken When the DTC Sets

DTC P0650, P263A, and P263B are Type B DTCs

Conditions for Clearing the DTC

DTC P0650, P263A, and P263B are Type B DTCs

Diagnostic Aids

• If the condition is intermittent, move the related harnesses and connectors while monitoring the scan tool MIL control circuit status parameters. Perform this test with the ignition ON and the engine OFF, and with the engine running. The MIL control circuit status parameters change from OK or Not Run to Malfunction if there is a condition with a circuit or a connection.
• If the ECM detects low voltage on the MIL control circuit during the control circuit driver OFF state, DTCs P0650 and DTC P263A may set simultaneously.

Reference Information

Schematic Reference

• Engine Controls Wiring Schematics (LTG)
• Instrument Cluster Wiring Schematics

Connector End View Reference

• Component Connector End View Index

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 the parameters listed below do not display Malfunction when commanding the Malfunction Indicator Lamp On and Off with a scan tool.

• The MIL Control Circuit Low Voltage Test Status
• The MIL Control Circuit Open Test Status
• The MIL Control Circuit High Voltage Test Status

If Malfunction is displayed

• Refer to Circuit/System Testing.

3. Engine running.

4. Verify the parameters listed below do not display Malfunction when commanding the Malfunction Indicator Lamp On and Off with a scan tool.

• The MIL Control Circuit Low Voltage Test Status
• The MIL Control Circuit Open Test Status
• The MIL Control Circuit High Voltage Test Status
• If Malfunction is displayed

Refer to Circuit/System Testing.

• Go to next step: If Malfunction is not displayed

5. Verify the malfunction indicator lamp turns ON and OFF when commanding the Malfunction Indicator Lamp On and Off with a scan tool.

• If the malfunction indicator lamp does not turn ON and OFF

Refer to Circuit/System Testing.

• Go to next step: If the malfunction indicator lamp turns ON and OFF

6. 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.

• If the DTC sets

Refer to Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis.

• Go to next step: If the DTC does not set

7. All OK.

Circuit/System Testing

1. Ignition OFF.

2. Disconnect the X1 harness connector at the K20 Engine Control Module.

3. Ignition ON, verify the malfunction indicator lamp does not illuminate.

• If the malfunction indicator lamp illuminates

1. Test for infinite resistance between the control circuit terminal X1 71 and ground.
   • If less than infinite resistance, repair the short to ground in the circuit.
   • If infinite resistance, replace the P16 Instrument Cluster.

• Go to next step: If the malfunction indicator lamp does not illuminate

4. Connect a 3 A fused jumper wire between the control circuit terminal X1 71 and ground.

5. Verify the malfunction indicator lamp illuminates.

• If the malfunction indicator lamp illuminates

Replace the K20 Engine Control Module.

• If the malfunction indicator lamp does not illuminate

1. Test for less than 1 V between the control circuit terminal X1 71 and ground.
   • If 1 V or greater, repair the short to voltage in the circuit.
   • Go to next step: If less than 1 V
2. Ignition OFF.
3. Test for less than 2 Ω in the control circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.
   • Go to next step: If less than 2 Ω.

6. Ignition OFF, disconnect the harness connector at the instrument cluster.

7. Ignition ON, verify a test lamp illuminates between the between the ignition voltage circuit terminal X1 8 and ground.

• If the test lamp does not illuminate and the circuit fuse is open

1. Ignition OFF.
2. Test for infinite resistance between the ignition voltage circuit and ground.
   • If less than infinite resistance, repair the short to ground in the circuit.

• If the test lamp does not illuminate and the circuit fuse is good

1. Ignition OFF.
2. Test for less than 2 Ω in the ignition voltage circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.

• Go to next step: If the test lamp illuminates

8. Replace the P16 Instrument Cluster.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

• Instrument Cluster Replacement
• Control Module References for control module replacement, programming, and setup

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