P0490-EGR CONTROL CIRCUIT HIGH





For a complete wiring diagram Refer to Section 8W

Theory of Operation


The EGR Solenoid is a two-wire electrically operated vacuum solenoid used to control the vacuum supply to the EGR Valve. The Solenoid receives 12 volts from the ECM/ASD relay and a pulse-width modulated ground signal from the ECM. The solenoid contains 2 vacuum ports. Vacuum from the vacuum pump system is supplied to one of the ports. The other port is connected to the EGR Valve. With the solenoid de-energized (off) the vacuum supply is blocked within the solenoid, prohibiting vacuum from reaching the EGR Valve. When the ECM energizes (grounds) the solenoid, the vacuum supply is applied to the EGR Valve causing the EGR Valve to open.



Possible Causes
INTERMITTENT DTC
(K35) EGR SOLENOID CONTROL CIRCUIT SHORTED TO VOLTAGE
(K35) EGR SOLENOID CONTROL CIRCUIT SHORTED TO THE (F344) FUSED ASD RELAY OUTPUT CIRCUIT
(K35) EGR SOLENOID CONTROL CIRCUIT OPEN OR HIGH RESISTANCE
EGR SOLENOID
ENGINE CONTROL MODULE (ECM)

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)



Diagnostic Test

1. DTC IS ACTIVE

Ignition on, engine not running.
With the scan tool, Clear DTCs in the Engine Control Module (ECM).
With the scan tool, actuate the EGR Solenoid at 100%.
Monitor the scan tool for at least two minutes.
Start the engine.
With the scan tool, select View DTCs.

Is the status Active for this DTC?

Yes


No

2. (K35) EGR SOLENOID CONTROL CIRCUIT SHORTED TO VOLTAGE



Turn the ignition off.
Disconnect the EGR Solenoid harness connector.
Disconnect the Engine Control Module harness connector.
Remove the ASD Relay from the TIPM.
Connect a jumper wire between cavity 30 and cavity 87 of the ASD Relay Connector.
Turn the ignition on.
Measure the voltage of the (K35) EGR Solenoid Control circuit in the EGR Solenoid harness connector.

Is there any voltage present?

Yes


No

3. (K35) EGR SOLENOID CONTROL CIRCUIT SHORTED TO THE (F344) FUSED ASD RELAY OUTPUT 2 CIRCUIT



Turn the ignition off.
Measure the resistance between the (K35) EGR Solenoid Control circuit and the (F344) Fused ASD Relay Output 2 circuit in the EGR Solenoid harness connector.

Is the resistance above 1000 ohms?

Yes


No

4. (K35) EGR SOLENOID CONTROL CIRCUIT OPEN OR HIGH RESISTANCE



Measure the resistance of the (K35) EGR Solenoid Control circuit between the EGR Solenoid harness connector and the Engine Control Module (ECM) harness connector.

Is the resistance below 10.0 ohms?

Yes


No