EGR System Test

Fig 1 EGR Valve And Components:

EGR system operation must first be checked with the DRB scan tool. To perform a test of the EGR system, refer to the appropriate Powertrain Diagnostic Procedures service manual. Check and correct any electrical malfunctions before proceeding.

Do not attempt to diagnose a defective EGR valve by applying vacuum to the EGR valve diaphragm fitting with engine running. Opening the EGR valve at idle speed will not change idle speed.

1. Check operation of EGR valve vacuum regulator solenoid and EGR system with DRB scan tool.

Fig 5 Engine Vacuum Pump:

2. Start engine and verify that vacuum is available at inlet fitting of EGR valve vacuum regulator solenoid. Vacuum is supplied by an engine driven vacuum pump (Fig. 5).
3. Check EGR valve for operation and leaks. Refer to EGR Valve Test.
4. Check operation of one-way check valve (Fig.1). Refer to Check Valve Test.