Voltage is provided to the exhaust gas recirculation (EGR) valve by the ignition 1 voltage circuit through a fuse. Ground is provided to the EGR valve on the control circuit by a low side driver within the engine control module (ECM). The ECM monitors the voltage on the control circuit of the EGR valve to determine if a failure is present.

The engine control module (ECM) monitors the position of the exhaust gas recirculation (EGR) valve through the EGR valve position sensor. The EGR valve position sensor sends a feedback voltage on the signal circuit to the ECM. The EGR position sensor voltage varies depending on the position of the EGR valve.

The EGR valve utilizes the following circuits:

The ECM detects the difference between the actual EGR position and the learned EGR position is greater than 10 percent.

DTC P0488 is a Type B DTC.

DTC P0488 is a Type B DTC.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exhaust Gas Recirculation (EGR) System Description

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON, observe the DTC information with a scan tool. DTC P0651 should not set.

⇒	If DTC P0651 is set, refer to DTC P0641 or P0651.

2. Observe the scan tool EGR Position Variance parameter while commanding the EGR valve to 100 percent. The reading should be less than 15 percent.
3. Engine running, observe the scan tool EGR position sensor percentage parameter. The reading should be less than 4 percent.
4. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

1. Ignition OFF, disconnect the harness connector at the EGR valve.
2. Ignition OFF, test for less than 1 ohm between the low reference circuit terminal 2 or B and ground.

⇒	If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

3. Ignition ON, verify that a test lamp illuminates between the ignition 1 voltage circuit terminal 5 or E and ground.

⇒	If the test lamp does not illuminate, test the ignition 1 voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition 1 voltage circuit fuse is open, test all components connected to the ignition 1 voltage circuit and replace as necessary.

Important: The 5-volt reference circuits are internally and externally connected at the ECM. Other component DTCs may be set. If other DTCs are set, review the electrical schematic and diagnose the applicable circuits and components.

4. Test for 4.8-5.2 volts between the 5-volt reference circuit terminal 4 or D and ground.

⇒	If less than the specified range, test the 5-volt reference circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the ECM.

⇒	If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.

5. Ignition OFF, verify a test lamp does not illuminate between the control circuit terminal 1 or A and B+.

⇒	If test lamp illuminates, test the control circuit for a short to ground. If the circuit tests normal, replace the ECM.

6. Ignition ON, command the EGR valve to 100 percent with a scan tool. The test lamp should illuminate.

⇒	If test lamp does not illuminate, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.

7. Verify the scan tool EGR position sensor parameter is less than 3 percent.

⇒	If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.

8. Install a 3A fused jumper wire between the signal circuit terminal 3 or C and the 5-volt reference circuit terminal 4 or D. Verify the scan tool EGR position sensor parameter is greater than 95 percent.

⇒	If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.

9. If all circuits test normal, test or replace the EGR valve.

1. Ignition OFF, disconnect the harness connector at the exhaust gas recirculation (EGR) valve.
2. Test for 6-10 ohms between the ignition 1 voltage terminal 5 or E and control terminal 1 or A.

⇒	If not within the specified range, replace the EGR valve.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.