EPR Vacuum Circuit Check
WARNING: This page does not describe the selected car, but rather 22 other vehicles, including the 1992 GMC Yukon, 1992 GMC Vandura Special, 1992 GMC Vandura, 1992 GMC Value Van, and 1992 GMC Rally Camper Special. However, it is still accessible from the selected car via links, so may be relevant.
The Exhaust Pressure Regulation (EPR) solenoid controls vacuum to EPR valve. When energized, EPR solenoid allows vacuum to close EPR valve, increasing exhaust backpressure for proper EGR operation.
NOTE:
Test numbers refer to numbers on diagnostic chart.
- This tests for normal EPR vacuum at idle. Since electrical circuit was already proven okay in EPR SOLENOID ELECTRICAL CHECK chart, absence of vacuum is due to no vacuum source (vacuum pump), or a restriction or leak in vacuum hose to valve, including a leak in solenoid.
- EPR solenoid is de-energized, no vacuum should be present.
- This tests for normal operation of EPR valve. When vacuum is applied to vacuum valve, valve actuator should move and hold.