EPR Solenoid Electrical Check
The Exhaust Pressure Regulation (EPR) solenoid controls vacuum to the EPR valve. When energized, EPR solenoid allows vacuum to close the EPR valve, increasing exhaust backpressure for proper EGR operation. The solenoid is supplied with 12 volts by ignition switch. The ECM completes ground circuit to energize the solenoid and turn EPR on when needed (EGR operation command).
Test Number 1) This tests for short to ground or a faulty ECM signal to EPR solenoid. Test light should normally be off.
Test Number 2) This tests for signal to energize EPR solenoid with engine at idle. If test light is on, electrical circuits to the solenoid are okay.
Test Number 3) This tests for voltage or open circuit from terminal "B" of EPR solenoid to ECM terminal C12.