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Deceleration Fuel Cut-Off System: Testing

  1. Connect Bosch test meter (KDJE 7453) to 2-pole test socket located near relay holder. Start engine and run at idle speed. Disconnect electrical connection from vacuum valve.
  2. Using probe, check that there is 12 volts between connector and ground. Increase engine speed to 2000 RPM. Suddenly release accelerator.
  3. Using hand, feel if vacuum valve is operating. Check that Lambda system assumes a fixed pulse relation (60%) until system cuts out at 1375 RPM.
Fig 1: Cutaway View of Vacuum Valve
G09323319Courtesy of SAAB-SCANIA OF AMERICA, INC.