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2002 Silverado with 5.3 charging problem?

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by donyms, Dec 6, 2012.

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  1. donyms

    donyms Rockstar 4 Years ROTM Winner 1000 Posts

    I think I may have a charging problem. The last couple of mornings when I start the truck the red battery warning in the message center comes on for a couple of seconds and then goes off for a couple of seconds. While the battery warning light is doing this I checked the alternator output and it was 14.4 with a digital meter. The light was still going on and off but there was no change on the meter. The warning light goes out after the truck warms up and the battery is getting a charge. I am thinking bad regulator maybe but i just don't know. Is 14.4 volts too much? Any ideas are appreciated.

    I have the stock "maybe original" 130 amp alternator and a new black top Interstate battery.
  2. RayVoy

    RayVoy Well-Known Member 2 Years 1000 Posts

    How long is this taking, and can you verify how many times it "flashes" the light?

    Is it only once? Does the light stay on longer than it should and then go out and stay out; or, does it come back on and stay on for a time, then go out a second time?

    BTW, 14.4 is fine.
  3. j cat

    j cat Rockstar 4 Years 1000 Posts

    when the red battery light comes on like you have I would get the battery load tested. remove and clean the battery connections first .

    when the engine is cold the voltage from the alternator will be high. if it is 0 deg f the voltage will be 15 volts. if its 120 deg f the voltage will be 13volts.

    with 40-50 deg f cold start 14volt range is good.

    I would guess you have a bad battery cell.
  4. donyms

    donyms Rockstar 4 Years ROTM Winner 1000 Posts

    It doesn't really flash but it comes on for about 5 seconds and then goes off for about 5 seconds. It will continue to do this until I take off down the road and then it goes out until the next time I do a cold start. I tried to video what the light was doing yesterday but when I started the truck the battery warning light didn't come on. I bought a black top Interstate battery 2.5 years ago and it was loosing it's charge over night so I got that replaced about a week ago and when I replaced it I also cleaned the cable ends and put a thin coat of electrical grease on all the connections. I will video the light when it does it again and post. Thanks for the help guys. :glasses:
  5. tbplus10

    tbplus10 Epic Member Staff Member 5+ Years 5000 Posts Platinum Contributor

    Have the battery load tested, just because it's new doesnt mean it's trouble free.
  6. RayVoy

    RayVoy Well-Known Member 2 Years 1000 Posts

    My guess, is just dirty connections; or, a loose connection. As the connection warms up, resistance goes down.

    Clean the battery connections, the alt connections and the battery ground connection.
    1 person likes this.
  7. j cat

    j cat Rockstar 4 Years 1000 Posts

    a bad connection as it gets hotter causes a higher resistance. this then reduces any alternator charge or power demand to the vehicle.

    if the battery is being drained when sitting for a period of time the battery voltage will be low . when first starting the computer will sense low battery voltage and throw the red battery LT on. then after a short period of time the alternator will restore the voltage to/across the battery to satisfy the low voltage sensor.

    could be bad connectors/alternator/battery/light in the glove box always on etc....

    testing and checking for these issues is required.
  8. RayVoy

    RayVoy Well-Known Member 2 Years 1000 Posts

    Your absolutely correct [MENTION=39185]j cat[/MENTION], that is what I said, but not what I intended (gotta learn to pay attention to what I type, hehe).

    What I intended to say was, as the under-hood temps warm up the connection, the resitance will decrease
  9. donyms

    donyms Rockstar 4 Years ROTM Winner 1000 Posts

    Well, the problem has gone for now. If it returns I will repost. Thanks for the input everybody. :glasses:
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