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Chart C-7C, EGR Check: Notes

NOTE: Test numbers refer to test numbers on diagnostic chart. Steps 1-3 represent an EGR functional check.
  1. This test checks to see if the EGR passages are restricted or if valve is stuck open. Engine should run roughly or stall as valve is opened manually.
  2. EGR valve diaphragm should begin to move as engine speed approaches 2000 RPM.
  3. This test should result in EGR solenoid being energized, shutting off vacuum to EGR valve. This indicates system is functioning properly.
  4. If vacuum is less than 7 in. Hg at 2000 RPM, a leak or restriction between the EGR diaphragm and vacuum source is indicated.
  5. With ignition on and engine stopped, ECM normally grounds terminal "T" to energize the EGR solenoid. This test checks EGR solenoid and solenoid electrical control circuit.
  6. The EGR is normally de-energized with the engine idling at normal operating temperature. This test checks EGR solenoid and solenoid electrical control circuit.
  7. This determines whether ECM is providing ground to terminal "T" or circuit No. 435 is shorted to ground.
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