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How do you check the alternator diode?

Updated: 10/22/2022
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9y ago

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If the car is running do an AC voltage drop test from the positive on the alternator to the positive battery terminal. there should be less than 0.1v ac. if there is greater than 0.1v that would indicate a failed diode. Another way is to remove the alternator from the vehicle and disassemble it, exposing the diode trio. Using a multimeter on the diode setting, test for continuity on each side of each diode. Continuity should be detected only one way on each diode. If this is not the case on any of the 3 diodes, then the diodes have failed and are in need of replacement.

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Q: How do you check the alternator diode?
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What wrong when battery lights blinks?

The diode in the alternator is probley going bad, Check charging system. And replace alternator.


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