GM Service Manual Online
For 1990-2009 cars only

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 provide an overview of each diagnostic category.

DTC Descriptor

DTC P0403:  Exhaust Gas Recirculation (EGR) Solenoid Control Circuit

Diagnostic Fault Information

Circuit

Short to Ground

High Resistance

Open

Short to Voltage

Signal Performance

EGR Position Sensor 5-Volt Reference

P0652

--

P0409

--

--

EGR Position Sensor Low Reference

--

--

P0409

--

--

EGR Motor W Position Signal

P0409

--

P0409, P042E

--

--

EGR Motor V Position Signal

P0409

--

P0409, P042E

--

--

EGR Motor U Position Signal

P0409

--

P0409, P042E

--

--

EGR Motor W Control

P0403

--

P0401, P0403

--

--

EGR Motor V Control

P0403

--

P0401, P0403

--

--

EGR Motor U Control

P0403

--

P0401, P0403

--

--

Circuit/System Description

The exhaust gas recirculation (EGR) valve is controlled by the engine control module (ECM) through the EGR motor high control and the EGR motor low control circuits. The ECM supplies voltage that is near ignition voltage to the high and low control circuits at all times. The ECM will pulse width modulation (PWM) the low control circuit to ground when EGR is desired. The lower the pulse width, the more the valve will open. The ECM will PWM the high control circuit to ground when the EGR valve is desired closed. If the ECM detects an electrical malfunction on the control circuits, DTC P0403 will set.

Conditions for Running the DTC

Condition 1

    • DTCs P0404, P0409, P042E, P0652 and P0653 are not set.
    • The battery voltage is between 10-16 volts.
    • The Ignition is ON for more than 2 seconds.

OR

Condition 2

    • DTCs P0652, P0653, P0409 and P0500 are not set.
    • The battery voltage is between 10-16 volts.
    • The Ignition is ON for more than 2 seconds after the ignition switch is OFF.
    • The engine speed is 0 RPM.
    • The vehicle speed is 0 km/h (0 mph).

Conditions for Setting the DTC

Condition 1

The EGR duty cycle is more than 70 percent for longer than 30 seconds.

OR

Condition 2

The ECM detects that the EGR valve position is not normal. The EGR position abnormal signal pattern is as follows:

    • U, V, W position: ON, ON, ON
    • U, V, W position: OFF, OFF, OFF
    • U, V, W position: OFF, ON, ON
    • U, V, W position: OFF, ON, OFF
    • U, V, W position: OFF, OFF, ON

Action Taken When the DTC Sets

DTC P0403 is a Type A DTC.

Conditions for Clearing the DTC

DTC P0403 is a Type A DTC.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End 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

Important: If you cannot duplicate the condition, 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.

Command the EGR valve to 30 percent with a scan tool. The commanded EGR position and the Actual EGR position should match.

If DTC P046C is also set, diagnose DTC P046C first.

Circuit/System Testing

  1. Test the EGR valve control circuit for a short to ground, a short to voltage, or a short to each other. If the circuits are normal, replace the EGR valve.
  2. Connect all previously disconnected components.
  3. Clear the DTCs with a scan tool.
  4. Turn OFF the ignition for 30 seconds.
  5. Start the engine and observe the scan tool current DTC information.
  6. If the DTC fails this ignition, replace the ECM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Exhaust Gas Recirculation Valve Replacement
    •  Control Module References for ECM replacement, setup, and programming