Quick question
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Quick question
65 f100. 352 3 speed manual.
My question; is the alternator light in the dash connected only to the alternator or will it also illuminate if the battery is dying or going bad and the alternator is functioning correctly?
Thank you
My question; is the alternator light in the dash connected only to the alternator or will it also illuminate if the battery is dying or going bad and the alternator is functioning correctly?
Thank you
Mountain Pass
Joined: Sep 2010
Posts: 238
Likes: 8
From: Princeton
Simply, the alternator light is positively connected to the battery and grounded through the alternator. This is why the light comes on when the key is turned on, but engine not started. When the engine starts, the alternator becomes positive and the light goes out because there is positive electricity to both sides of the bulb. If the light comes on brightly with engine running, it means alternator is not charging. In that event the light has positive electricity from the battery to one side of the bulb and negative to the other side through the non-charging alternator thereby completing the circuit. If the light comes on dimly, it means alternator is not charging fully. In that event the light has positive from the battery on one side and some positive on the other side from a barely charging alternator, but it is more negative than positive thereby allowing the light to burn dimly. Well, something like that anyway.
Mountain Pass
Joined: Sep 2010
Posts: 238
Likes: 8
From: Princeton
If it is wired correctly, I do not see how the alternator light could indicate a bad battery. Is it possible for the alternator light to come on with a good charging system? Yes, under certain conditions. None of this is absolute, but the alternator controls the light, not the battery. Have your alt and battery checked for free at the local auto parts store to be sure.
In these old trucks though, there are a million things that could go wrong. The wiring is old and brittle, and it's probably been tinkered with by every Tom, Dick and Harry and their relatives, so unusual things can happen. Troubleshooting these things can be challenging, because you can't assume anything.
In these old trucks though, there are a million things that could go wrong. The wiring is old and brittle, and it's probably been tinkered with by every Tom, Dick and Harry and their relatives, so unusual things can happen. Troubleshooting these things can be challenging, because you can't assume anything.
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Ford Inline Six, 200, 250, 4.9L / 300
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