EPR Vacuum Check
The EPR solenoid controls vacuum to EPR valve. EPR solenoid, when energized, allows engine vacuum pump vacuum to close EPR valve. Battery voltage is supplied from ignition, and ECM completes the ground to energize solenoid. A vacuum leak will cause a steady CEL after 10 seconds of engine running with the leak present. CEL will remain "ON" even if the vacuum leak is repaired, unless the key is turned "OFF" and "ON."
- This step checks for vacuum at EPR solenoid with engine idling.
- The ECM normally completes the ground to open the EPR solenoid allowing vacuum to the valve. By removing the electrical connector, the vacuum should fall to near zero.
- This step checks for a leak in the EPR valve or hoses.
- Valve should move as vacuum is applied. If valve moves, fault is in solenoid or connections.