EPR Vacuum Check
The EPR solenoid controls vacuum to EPR valve. The EPR solenoid, when energized, allows vacuum pump vacuum to close 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, increasing exhaust system back pressure and allowing the EGR valve to function more efficiently.
NOTE:
The following step numbers refer to the numbers in the accompanying flow chart(s).
- Checks for normal EPR vacuum at idle. Electrical circuit was verified as OK on prior chart. Absence of vacuum here is due to source failure (vacuum pump) or a restricted/leaking vacuum line to the valve.
- Checks to see if solenoid will respond to ECM command.
- Checks for normal operation of EPR valve.
NOTE:
See EPR Solenoid Electrical Check for wiring.