Battery Light On

[kjctaco]

I searched but did not find an answer. This morning my 01 z71 died. I had my wife tow me home and figured out the alternator had died. I replaced the alternator and the truck fired right up and runs fine but now the red battery light is on. It stays on for about 5 seconds and then turns off for about 5 seconds cycling continuously. I removed the battery cables for about an hour and tried another battery to reset it and nothing changed. Anyone have an idea why the light is on?

[C. Charles Hahn]

Hmm... I was going to suggest maybe a bad cell in the battery, but since you tried a different battery it kind of rules that out.

 

Maybe take your truck to the local autozone and have them run a load test on the charging system and check for thrown DTCs? Could be something else other than the alternator is drawing on the charging system....

[Diesail]

I would meter the output of the alternator and see what the voltage is doing there. If it is cycling up and down just like the light then it is a bad alternator. If it stays steady at around 14 volts then you have a loose connection someplace.

[kjctaco]

what is the best way to check the alternator output. I have a voltage meter, where would i check it at?

[dlewis1111]

what is the best way to check the alternator output. I have a voltage meter, where would i check it at?

 

voltmeter isnt going to tell you the amperage output. drive it to autozone or advance and have them check your entire charging system for free

[az'03Silverado]

You can check the voltage at the battery when the engine is running. But, like dlewis1111 said, system current is a better indicator.

[Diesail]

what is the best way to check the alternator output. I have a voltage meter, where would i check it at?

 

 

Look at the back of the alternator for the large red charge wire. Pull the boot back just enough to expose the connecton. Check your voltage there, then at the battery. If you have a solid voltage at the alternator then you are most likely looking for a loose or corrored connection someplace.