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B&B??Battery light comes on n off

Discussion in 'Chevy Trucks' started by flykelley, Jan 6, 2010.

  1. flykelley

    flykelley 2000 Club Member
    Messages: 2,124

    2005 2500HD with the plow prep so the Alt is a 140 amp. The light has come on and off about 5 times today, stays on for about 30 seconds then goes off. Most of the time the amp meter shows just a small drop to just under 14 amps. Im thinking its the Alt going bad but want to make sure its not the batterys. Thoughts please.

    Regards Mike
  2. JDiepstra

    JDiepstra PlowSite.com Addict
    Messages: 1,780

    I had my check gauges light come on a few times and found that my battery gauge was very low. My plow motor was sticking on. I changed the solenoid and problem solved.
  3. Clint S

    Clint S Senior Member
    Messages: 280

    Probably the alt going.
  4. Detroitdan

    Detroitdan PlowSite.com Addict
    Messages: 1,937

    My alternator went yesterday. Battery light was on and the gauge read low. Went through all the connections and eventually had to put a new alternator in it. I've already replaced it once, of course the sticker was long gone so Napa wouldn't warranty it. I could have sworn I put a HD alt in there last time, but when they sent over the HD model it was wrong and wouldn't even mount up. So I got the regular version (105 amp) and it matched right up. I was bummed because I like to upgrade things when I replace them.
    It's wierd, this is the first truck I've owned long enough to replace something more than once. I've used up two new sets of tires, replaced the entire exhaust system twice and batteries twice.

    I suspect the alternator may have been helped along on it's demise. I recently had a transmission cooler line come apart right next to it, and no doubt soaked it thoroughly.
  5. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Start with the obvious things first Mike. Battery connections, load test the batteries, be sure the charge wire is tight etc. And don't forget to check the engine side ground connection. It's down low on the engine block and thus can be very susceptible to corrosion. Also clean the few ground wires on the driver side front body mount just under the door. Will be either two or three there and make sure they're spotless.

    Also, wiggle the plug on the alt while an observer watches for the battery icon to illuminate. Tug it one way and hold, tug it another way and hold as it takes the icon a few seconds to react to a no/low charge condition, the system voltage has to be below 10.5 V for 5 seconds minimum for it to illuminate.

    If everything thus far checks out then it's likely the alternator is slow to excite and it's time for a replacement. You can get a true 200 AMP alternator from your local NAPA for just a few more dollars than you'd spend on a stock rebuilt unit so take that into consideration.
  6. flykelley

    flykelley 2000 Club Member
    Messages: 2,124

    Ok Guys
    This is what I found, both positive and negative battery cables were loose. positive about 1/2 turn and the negative was about 1/4 turn. Put meter on output side of alt and it reads a steady 14 volts. Cleaned the ground wire at the frame and the engine and gave them a shot of FF. I'm going to do some driving around and if the battery not charging light comes back on I am going to change the alt. Thanks for all of the advise.