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Home >> Mercedes Benz >> 2012 >> ML 350 4MATIC (166.057) V6-3.5L (276.955) >> Repair and Diagnosis >> Starting and Charging >> Charging System >> Alternator >> Rectifier Diode / Bridge >> Service and Repair
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Rectifier Diode / Bridge: Service and Repair



AR15.40-P-9301-02GQ Test Alternator Diodes





Connection diagram shown for model 166.0

030 Engine tester with oscilloscope
065 DC clip-on probe

F32/3 Engine compartment prefuse box
G1 On-board electrical system battery

G2 Generator
M1 Starter
W10 Front right on-board electrical system battery ground point

1 Connect engine tester with oscilloscope (030).

2 Start engine.

3 Switch on low beams.
In this test it is not possible to assess the exciter diodes.

4 Assess diode harmonics at 3000 rpm (engine speed).





Harmonics of the diodes is OK (example)

Voltage peaks are possible but without meaning.





Harmonics when a positive diode is faulty (example).





Harmonics when a negative diode is faulty (example).

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