Electronic EGR Transducer Test

TESTING ELECTRICAL SOLENOID PORTION OF VALVE CONTROL

NOTE: This is not to be used as a complete test of the EGR system.

Electrical operation of the valve control should be checked with the DRB scan tool. Replace solenoid (valve control) if necessary.

TESTING VACUUM TRANSDUCER PORTION OF VALVE CONTROL

The first part of this test will determine if the transducer diaphram at the back-pressure side of the valve control has ruptured or is leaking. The second part of the test will determine if engine vacuum (full-manifold) is flowing from the inlet to the outlet side of the valve control. This is not to be used as a complete test of the EGR system.
1. Electrical operation of the valve control should first be checked with the DRB scan tool before proceeding with the vacuum test.

EGR Valve And Control:

2. Disconnect the rubber back-pressure hose from the fitting at the bottom of EGR valve control.
3. Connect a hand-held vacuum pump to this fitting.
4. Apply 10 inches of vacuum to this fitting.
5. If vacuum falls off, the valve control diaphragm is leaking.
6. Replace the EGR valve control. Proceed to next step for further testing.
7. Remove the rubber hose at the vacuum inlet fitting on the EGR valve control.
8. Connect a vacuum gauge to this disconnected hose.
9. Start the engine and bring to operating temperature. Hold engine speed at approximately 1500 rpm.
10. Check for steady engine vacuum (full-manifold) at this hose.
11. If engine vacuum (full-manifold) is not present, check vacuum line to engine and repair as necessary before proceeding to next step.
12. Reconnect the rubber hose to the vacuum inlet fitting on the EGR valve control.
13. Disconnect the rubber hose at the vacuum outlet fitting on the EGR valve control.
14. Connect a vacuum gauge to this fitting.

EGR System Location:

15. Disconnect the electrical connector at the valve control. This will simulate an open circuit (no ground from the PCM) at the valve control.
16. Start the engine and bring to operating temperature. Hold the engine speed to approximately 2000 rpm while checking for engine vacuum (full-manifold) at this fitting. To allow full manifold vacuum to flow through the valve control, exhaust back-pressure must be present at valve control. It must be high enough to hold the bleed valve in the transducer portion of the valve control closed. Have a helper momentarily (a second or two) hold a rag over the tailpipe opening to build some exhaust back-pressure while observing the vacuum gauge. Heavy gloves should be worn.

CAUTION: Do not cover the tailpipe opening for an extended period of time as damage to components or overheating may result.

As temporary back-pressure is built, full manifold vacuum should be observed at the vacuum control outlet fitting. Without back-pressure, and engine at approximately 2000 rpm, the gauge reading will be low. This low reading is normal. At idle speed, the gauge reading will be erratic. This is also normal.
17. If full manifold vacuum is not present at the outlet fitting, but was present at the inlet fitting, replace the valve control.

NOTE: The EGR valve, valve control and attaching hoses are serviced as one unit.