Exhaust Gas Recirculation: Testing and Inspection

WARNING: If the EGR valve is hot, wear gloves to avoid burning fingers.

1. Start the engine.
2. Run the engine to normal operating temperature.
3. Raise and suitably support the vehicle's drive axles.
4. Place the transmission in Neutral and the transfer cases in 2H. Check that the propeller shaft is turning (the PCM must see VSS input for operation of the EGR solenoid vacuum valve).
5. Place one finger on the Exhaust Gas Recirculation (EGR) valve diaphragm and accelerate the engine. The diaphragm should move.
6. Disconnect the vacuum hose from the EGR valve.
7. Use a hand vacuum pump and apply 27 kPa (8 in. Hg.) of the vacuum to the EGR valve with one finger on the diaphragm. The diaphragm should move and the engine should run rough and may stall.

Inspect
Check for carbon deposits in the valve which may cause a restriction in flow. The restriction may be small enough so that the engine may not stall during Step 7, yet large enough to cause a DTC to set. If the valve passes the above test, check the Exhaust Gas Recirculation (EGR) pressure transducer. Replace the valve if it fails the above test.