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Home >> Mitsubishi >> 1993 >> Expo Base, AWD, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests >> Motors, Relays & Solenoids >> Relays >> MPI Control Relay
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MPI Control Relay

  1. This step checks ignition switch supply voltage of control relay. Disconnect control relay connector. Turn ignition on. Using DVOM, measure voltage between terminal No. 8 of relay harness connector and vehicle ground. See Fig 1 . If voltage is battery voltage, go to step 2. If voltage is not battery voltage, check and repair circuit between ignition switch and control relay.
  2. This step checks continuity of control relay ground circuit. Turn ignition off. Using DVOM, check continuity between control relay harness connector terminal No. 6 and vehicle ground. If continuity exists, go to step 3. If continuity does not exist, check and repair circuit between control relay and vehicle ground.
  3. This step checks battery supply voltage of control relay. Using DVOM, measure voltage between terminal No. 4 of relay harness connector and vehicle ground. If voltage is battery voltage, go to step 4. If voltage is not battery voltage, check and repair circuit between battery and control relay.
  4. This step checks continuity of circuit between control relay and ECM. Disconnect ECM connector. Using DVOM, check continuity between control relay harness connector terminal No. 3 and ECM connector terminals No. 12 and 25. See Figure and Fig 1 . If continuity exists, go to step 5. If continuity does not exist, check and repair circuits between control relay harness connector and ECM.
  5. This step checks supply voltage to control relay actuator. Connect ECM and MPI control relay connectors. Using DVOM, backprobe control relay terminal No. 2. With engine cranking, voltage should be 8 volts or greater. Start engine and run at 2500 RPM or greater. If voltage is battery voltage, harness is okay. If voltage is not battery voltage, go to step 6.
  6. If control relay tests okay in steps 6 through 8, replace ECM. Removal of relay may assist in testing. Continuity should exist between terminals No. 5 and 7. Measure resistance between terminals No. 6 and 8. Continuity should exist in only one direction. Replace control relay if continuity is not as specified.
  7. Connect 12-volt power source between relay terminals No. 5 and 7. Connect positive lead to terminal No. 7. With relay energized, battery voltage should exist between terminals No. 1 and 5. With power source removed, voltage should not exist.
  8. Move 12-volt power source to relay terminals No. 6 and 8. Connect positive lead to terminal No. 8. With relay energized, continuity should exist between terminals No. 2 and 4 and between terminals No. 3and 4. With power source removed, continuity should not exist. Replace control relay if measurements are not as specified.
    Fig 1: MPI Control Relay Connectors ID
    G93C78453Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
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