Before performing this test, please check the following.
- Generator mounts.
- Make sure that the battery installed in the vehicle is fully charged.
- Drive belt tension.
- Fuse link.
- The presence of extraneous noise coming from the generator when the engine is running.
Turn the ignition key to the "LOCK" position.
Disconnect the negative cable from the battery.
Using the Generator Test Harness (MB991519), connect a digital voltmeter between the generator "S" terminal and vehicle ground. (Connect the positive lead of the voltmeter to the "S" terminal and the negative lead to a good ground or to the negative battery terminal.).
Connect a 0-120A DC clip-on ammeter to the wire between the alternator "B" terminal and the battery.
Attention! Connecting a conventional ammeter to a break in the circuit is possible if the electrical contact between the generator terminal "B" and the current wire is not broken.
Connect the negative cable to the battery.
Connect a tachometer or MUT-II/III diagnostic tool.
Turn the ignition key to the "ON" position. The voltmeter should show battery voltage.
Attention! If the voltmeter shows a voltage of 0 V, the probable cause may be a break in the connecting wire or fuse between the generator terminal "S" and the positive terminal of the battery.
Turn off all lighting fixtures and other electrical consumers.
Start the engine.
Increase engine speed to 2500 min⁻¹.
Record the voltmeter readings when the generator current is equal to or less than 10 A.
If the measured voltage is within the set range, the voltage regulator is working properly.
If the measured voltage does not correspond to the set range, then the generator itself or the voltage regulator is faulty.
After checking, release the accelerator pedal.
Turn the ignition key to the "LOCK" position.
Disconnect the tachometer or MUT-II/III diagnostic tool.
Disconnect the negative cable from the battery.
Disconnect the ammeter and voltmeter.
Connect the generator current wire to the "B" terminal of the generator.
Disconnect the generator test harness, reconnect all electrical connectors.
Connect the negative cable to the battery.
Generator regulated voltage (nominal value)
(The article is based on data from the website: mitsubishiman)