For a complete wiring diagram Refer to Section 8WPossible CausesVACUUM SUPPLY TO EGR SOLENOIDEGR SOLENOIDEGR VALVE1. VACUUM SUPPLY TO EGR SOLENOIDTurn the ignition off.Disconnect the vacuum supply hose to the EGR Solenoid.Connect a vacuum gauge to the disconnected vacuum supply hose to the EGR Solenoid.Start and idle the engine.Observe the vacuum gauge reading. Does the vacuum gauge display vacuum above 24 inches of mercury?YesGo To 2NoCheck vacuum pump and vacuum supply system for problems related to low vacuum.Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - STANDARD PROCEDURE)2. VACUUM SUPPLY TO EGR VALVEThe engine must be at operating temperature for this test.Turn the ignition off.Reconnect the vacuum supply hose to the EGR Solenoid.Disconnect the vacuum hose at the EGR Valve.Connect a vacuum gauge to the disconnected vacuum hose at the EGR Valve.Start and idle the engine.Observe the vacuum gauge reading for 30 seconds beginning at engine start up. Does the vacuum gauge display vacuum above 14 inches of mercury for approximately 16.0 seconds from engine start up then drop to 0?YesGo To 3NoCheck the vacuum hose between the EGR Solenoid and the EGR Valve for crack, kinks cuts, or other damage that may prevent proper vacuum operation. If the hose is functioning properly, replace the EGR Solenoid.Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - STANDARD PROCEDURE)3. EGR VALVETurn the ignition off.Reconnect the vacuum hose at the EGR Valve.Disconnect both vacuum hoses at the EGR Solenoid.Using a vacuum tee connector, connect both disconnected hose ends at the EGR Solenoid.This test will apply continual vacuum to the EGR Valve. If the EGR Valve is functioning properly, a dramatic loss of engine power will occur when attempting to accelerate and/or load the engine.Test drive the vehicle.Does the vehicle exhibit a noticeable loss of power on acceleration?YesTest Complete.NoReplace the EGR Valve in accordance with the Service Information.Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - STANDARD PROCEDURE)