Battery Light, Diode / Resistor Question

[Ras12]

My battery light is on pretty consistently. I took it to the local auto parts store and they ran a test on the battery and it came out good. The test showed the charge going to the battery was around 13v but detected a “bad diode or faulty resistor.” Anyone every experience this? Any input would be greatly appreciated.

[Ras12]

Bueller? Bueller? Bueller?

[Ron]

lol

13V sounds right if one of the 6 main diodes in the rectifier are bad.
A "bad resistor" usually refers to a shunt resistor that rests on top of the voltage regulator/brush holder of an older style GM integrated alternator, 10SI iirc... It is usually not needed. A smaller set of diodes are also used in these units ("diode trio"). They go between the rectifier and the regulator. Depending on the tester, “bad diode or faulty resistor” could be generic/catch all for any of the above. In any case, I'd remove the unit and have it load tested at your local auto parts (free)...

[iflights]

Agree on the recommendation.

Fortunately, removing the alternator is not a difficult task and having gone through a similar situation as what is described, I wish I had started with getting the alternator tested.