16-GENERATOR OUTPUT LINE VOLTAGE DROP TEST

GENERATOR OUTPUT LINE VOLTAGE DROP TEST

Required Special Tools:

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

This test determines whether the wiring from the generator "B" terminal to the battery (+) terminal (including the fusible line) is in a good condition or not.

1. Always be sure to check the following before the test.

Generator installation
Drive belt tension
(Refer to GROUP 11A - On-vehicle Service - Drive Belt Tension Check ).
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. Set a clamp-type DC test ammeter to the generator "B" terminal output wire.

note	Disconnecting the generator output wire and connecting the ammeter may not thoroughly diagnose an generator output line resistance increase problem because of an insufficient connection between terminal "B" and the output wire.

5. Connect a digital-type voltmeter between the generator "B" terminal and the battery (+) terminal. [Connect the (+) lead of the voltmeter to the "B" terminal and connect the (-) lead of the voltmeter to the battery (+) cable].

6. Reconnect the negative battery cable.

7. Connect scan tool (M.U.T.-IIISE) to show the engine speed.

8. Leave the hood open.

9. Start the engine.

10. With the engine running at 2,500 r/min, turn the headlights and other lights on and off to adjust the generator load so that the value displayed on the ammeter is slightly above 30 A.

Adjust the engine speed by gradually decreasing it until the value displayed on the ammeter is 30 A. Take a reading of the value displayed on the voltmeter at this time.

Limit: maximum 0.3 V

note	When the generator output is high and the value displayed on the ammeter does not decrease until 30 A, set the value to 40 A. Read the value displayed on the voltmeter at this time. When the value range is 40 A, the limit is maximum 0.4 V.

11. If the value displayed on the voltmeter is above the limit value, there is probably a malfunction in the generator output wire, so check the wiring between the generator "B" terminal and the battery (+) terminal (including fusible link).

If a terminal is not sufficiently tight or if the harness has become discolored due to overheating, repair and then test again.

12. After the test, run the engine at idle.

13. Turn off all lights.

14. Turn the ignition switch to the "LOCK" (OFF) position.

15. Disconnect the scan tool (M.U.T.-IIISE).

16. Disconnect the negative battery cable.

17. Disconnect the ammeter and voltmeter.

18. Connect the negative battery cable.