EPR Vacuum Circuit Check

Circuit Description:
The EPR solenoid controls vacuum to the EPR valve. The EPR solenoid, when energized, allows vacuum pump vacuum to close the EPR valve and increase exhaust back pressure for proper EGR operation. The EPR valve is a combination vacuum actuator and exhaust restrictor plate. When vacuum is applied to the actuator, the restrictor plate closes to increase exhaust system back pressure to allow the EGR valve to function more efficiently.

Test Description:
Numbers below refer to circled numbers on diagnostic chart.
1. Checks for normal EPR vacuum at idle. Since electrical circuit was verified as OK on prior chart, if no vacuum is present, it is due to no source vacuum (vacuum pump) or a restriction or leak in vacuum lines to valve, including the solenoid.
2. EPR solenoid is de-energized, so no vacuum should be present.
3. Checks for normal operation of EPR valve. When vacuum is applied, valve actuator should move and hold.