Test 2

For EGR function testing, see appropriate SYSTEM & COMPONENT TESTING article.

1994

1. Ensure EGR vacuum modulator filter is clean and in good condition. Clean filter with compressed air (if necessary).
2. Using "T" connector, install vacuum gauge in vacuum line to EGR valve. Start engine. Ensure engine runs idles smoothly to ensure proper seating of EGR valve.
3. Install Jumper Wire (SST 09843-18020) between terminals TE1 and E1 of data link connector No. 1, located in engine compartment.
   NOTE: The EGR system components can be checked with engine coolant temperature less than minimum temperature and engine at specified engine RPM.
4. Warm engine to normal operating temperature. Operate engine at 2500-3500 engine RPM again. Ensure a low vacuum reading is now obtained.
5. Disconnect vacuum hose from port "R" of EGR vacuum modulator. See Fig 1. Using additional hose, connect port "R" of EGR vacuum modulator directly to intake manifold. High vacuum reading should be obtained at 2500-3500 engine RPM.
   NOTE: Engine should misfire due to large amounts of exhaust gas being injected into intake manifold.
6. Remove vacuum hose and reconnect original vacuum hose to EGR vacuum modulator. To check EGR valve operation, remove vacuum hose from EGR valve.
7. Using vacuum pump, apply vacuum directly to EGR valve with engine idling. Engine should run rough or stall. If EGR system does not operate as described, each individual component should be tested. Shut engine off. Remove jumper wire from data link connector No. 1.