Regulated Voltage Test: Notes

Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.

Required Special Tools: 

• MB991519: Generator Test Harness
• MB992744: Vehicle communication interface-Lite (V.C.I.-Lite)
• MB992745: V.C.I.-Lite main harness A
• MB992747: V.C.I.-Lite USB cable short
• MB992748: V.C.I.-Lite USB cable long
• MB991958: Scan Tool (M.U.T.-III Sub Assembly)
  • MB991824: Vehicles Communication Interface (V.C.I.)
  • MB991827: M.U.T.-III USB Cable
  • MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)
• MB991519: Generator Test Harness

This test determines whether the voltage regulator correctly controlling the generator output voltage.

1. Always be sure to check the following before the test.
   • Generator installation
   • Check that the battery installed in the vehicle is fully charged (Refer to BATTERY TEST ).
   • Drive belt tension (Refer to DRIVE BELT TENSION CHECK AND ADJUSTMENT ).
   • Fusible link
   • Abnormal noise from the generator while the engine is running
2. Turn the ignition switch to the "LOCK" (OFF) position.
3. Disconnect the negative battery cable.
4. Use the generator test harness special tool (MB991519) to connect a digital voltmeter between the generator "S" terminal and ground (Connect the positive lead of the voltmeter to the "S" terminal, and then connect the negative lead of the voltmeter to a secure ground or to the negative battery terminal).
5. Set a clamp-type DC test ammeter to the generator "B" terminal output wire.
   NOTE: The way of disconnecting the generator output wire and of connecting the ammeter is possibly not found the problem that the output current is dropping due to the insufficient connection between terminal "B" and the output wire.
6. Reconnect the negative battery cable.
   CAUTION: To prevent damage to scan tool (M.U.T.-III), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-III).
7. Connect scan tool (M.U.T.-III) to the data link connector [Refer to MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS ].
8. Turn the ignition switch to the "ON" position and check that the reading on the voltmeter is equal to the battery voltage.
   NOTE: If the voltage is 0 volt, the cause is probably an open circuit in the wire or fusible link between the generator "S" terminal and the positive battery terminal.
9. Turn all lights and accessories off.
10. Start the engine.
11. Using the scan tool (M.U.T.-III), select data list item number 2 "Crank angle sensor" in MFI system and check that the engine speed (Refer to DATA LIST REFERENCE TABLE ).
12. Increase the engine speed to 2, 500 r/min.
13. Read the value displayed on the voltmeter when the generator output current generator becomes 15 amperes or less.
14. If the voltage reading conforms to the value in the voltage regulation table, then the voltage regulator is operating normally.

    If the voltage is not within the standard value, there is a malfunction of the voltage regulator or of the generator.

    NOTE: When the voltage is approximately 12.8 volts, the "G" terminal is supposed to have a short circuit to the ground. Check the circuits relating to the "G" terminal on the generator (Refer to SYMPTOM CHART ).
15. After the test, lower the engine speed to the idle speed.
16. Turn the ignition switch to the "LOCK" (OFF) position.
17. Disconnect the scan tool (M.U.T.-III) to the data link connector.
18. Disconnect the negative battery cable.
19. Disconnect the ammeter and voltmeter.
20. Remove the generator test harness special tool (MB991519) and return the connector to the original condition.
21. Connect the negative battery cable.