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Digital EGR Valve - 1990-1992 3.1L, 3.4L & 3.8L

NOTE: A Tech 1 scan tester or a tester capable of cycling ECM output devices may also be used to perform EGR function test.
  1. Turn engine off. Disconnect EGR valve electrical connector. Start engine and allow engine to idle. Using a 12-volt power source and a fused jumper wire, apply voltage to terminal "D" of EGR valve. See Fig 1 .
    NOTE: EGR valve wire colors may vary.
  2. Using a jumper wire with one end connected to a good ground, alternately touch remaining end of jumper wire to EGR valve terminals "A", "B", and then "C". Engine RPM should change as each EGR valve terminal is contacted. If engine RPM changes, EGR valve is functioning correctly.
  3. If engine RPM does not change, check for restriction in EGR supply tube or plugged EGR valve orifice. If EGR valve is not restricted or plugged, EGR valve is defective.
Fig 1: Digital EGR Valve Circuit (1988-92 3.1L, 3.4L & 3.8L)
G90A09034Courtesy of GENERAL MOTORS CORP.