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EPR Solenoid Electrical Check: Notes

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. The solenoid is supplied with 12 volts by ignition switch. ECM completes ground circuit to energize solenoid, and turn EPR on when needed (EGR operation command).

NOTE: Test numbers refer to numbers on diagnostic chart.
  1. This tests for short to ground, or a faulty ECM signal to EPR solenoid. Test light should normally be off.
  2. This tests for signal to energize EPR solenoid with engine at idle. If test light is on, electrical circuits to solenoid are okay.
  3. This tests for voltage or open circuit from terminal "B" of EPR solenoid to ECM terminal C12 ("C" & "K" Series) or F16 ("G" Series) on circuit No. 439 ("C" & "K" Series) or No. 39 ("G" Series).
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