Battery Light

[wrpsuite]

Haven't been driving my truck much lately but last week when i started it battery light came on. Had tools with and headed to parts store thinking original alternator finally giving out and could die at any moment.

Tested voltage- 12.6 across terminals, charging at 14.7 skipped the purchase and drove home 3 hours, got home and load tested and it's fine started perfect all week just not sure why battery light is on?

 

[brillo_76]

Possible dirty terminals.

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[wrpsuite]

Will start there and see what happens thanks


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[Sarki]

Possible dirty terminals.

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I like how you think Brillo.
So many times we look past the more obvious and move on to the more complicated or expensive potential sources for the problem......i’m guilty of the same!
Best to start by eliminating the more basic and cheap ones first.

 

[photoleif]

brillo's fix first.

another reason the battery light comes on is an LED swap. i just had to revert to incandescent on mine for that indicator.

 

[19963.4lsr5]

Battery post cleaner and terminal remover should be in everyone’s toolbox.


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[brillo_76]

As old as these rigs are now. The chances of terminal and connections at the battery post being severely oxidized and those causing major resistance and bad conduction.

 

[wrpsuite]

Cleaned battery, replaced terminals, checked ground wire, checked wires going to alternator and light still on. Making me crazy and worried to get stranded. May have to take alternator out and have bench tested.


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[19963.4lsr5]

Cleaned battery, replaced terminals, checked ground wire, checked wires going to alternator and light still on. Making me crazy and worried to get stranded. May have to take alternator out and have bench tested.


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Hit your Alt with a hammer. If the light goes out either replace the brush assemble or get another alternator.


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[brillo_76]

Mostly the battery light comes on when the vehicle isn't charging. That's when mine came on.


So your getting 14.7 volts across the terminals when the engine is running is this at idle? As the these mostly dont charge much at idle.

Maybe your voltage regulator is failing and your voltage is going too high thus why your light is on.




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[wrpsuite]

12.7 when off
Drops to 11.5 when cranking
14.3 at idle
Smacked alternator battery light still on scratching head.


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[LittleCaesar]

Take it to a local auto parts store (NAPA if you have one) and have them load test it.

It seems to be charging, but possibly overcharging the battery.

 

[wrpsuite]

Had it load tested when first came on not the problem but thanks


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[19963.4lsr5]

12.7 when off
Drops to 11.5 when cranking
14.3 at idle
Smacked alternator battery light still on scratching head.


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What bulb do you have in for the battery light?

If you have an LED in it, it won’t work. The lamp is part of the circuit.

14.3 at the battery is good.


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[wrpsuite]

Stock light


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[brillo_76]

Now I am starting to scratch my head as there has to.be a reason this light is on
.:/

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[19963.4lsr5]

What is your voltage at the charge post of the alternator?

That light may also come on if the V regulator is failing and outputting too high of voltage.

If your voltage is above 14.5 at the post and you have jumper cables use them to ground the Alt to the negative post of the battery and frame.


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[wrpsuite]

What is your voltage at the charge post of the alternator?

That light may also come on if the V regulator is failing and outputting too high of voltage.

If your voltage is above 14.5 at the post and you have jumper cables use them to ground the Alt to the negative post of the battery and frame.


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14.7 at the alternator post, can you elaborate on the test you mentioned?

 

[wrpsuite]

mechanic friend told me he thinks reference wire in regulator is shorted and alternator is bad ??

 

[brillo_76]

mechanic friend told me he thinks reference wire in regulator is shorted and alternator is bad ??

I been saying bad terminals or alternator from the beginning.. I know when i was loosing my ground in the alt my ground lugs would glow red at night under the hood.

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