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Voltage guage...

Discussion in 'Chevy Trucks' started by mkwl, Feb 5, 2008.

  1. mkwl

    mkwl 2000 Club Member
    Messages: 2,362

    I've noticed over the last couple months that my voltage guage "varies" a little more than the rest of our trucks. When the truck is idling or accelerating/decelerating the guage needle moves up/down 1-2 "tick marks" from the middle of the guage at 14 volts. Is this normal without any additional electrical loads on the truck?

    The guage dips down a little when I'm using the plow- more than it "varies" by itself, but can't figure out why it would do this with no real change in the curent draw on the truck.

  2. mike33087

    mike33087 Senior Member
    Messages: 555

    how old is the battery? and do u run 1 or 2
  3. mkwl

    mkwl 2000 Club Member
    Messages: 2,362

    Battery is about 2 years old- I run one battery. It's got a 145A alt.
  4. OhioPlower

    OhioPlower Senior Member
    Messages: 440

    My dmax was doing the same thing about a month ago and the lights were dimming a little bit too while the gauge was bouncing and that was without the plow. Ended up going to the dealer to milk my extended warranty that was up in 200 miles and they said it was the alternator and batteries. They replaced those things for $0 and its good as new now. Plow seems a little bit faster and my lights dim less. Oh yea the dealer said the alternator was about $380 and the batteries were about $110 or 120. Cant remember exact numbers cuz I didnt pay for it.
  5. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Use a digital volt meter and connect it directly to the battery and watch the voltage. Does it fluctuate up and down like the volt gage in the truck? If not, then the stepper motor in the gage itself is going bad. Very common problem on the 03-05 GM trucks.

    If the voltage does fluctuate when checking directly at the battery, then you either have a battery or alternator problem. A loose battery cable or poor cab to frame ground will cause it too.
  6. saabman

    saabman Member
    from Maine
    Messages: 70

    Fluctuating volage is often indicative a failed voltage regulator in the alternator. With a volt meter is if you see the voltage cycle from 12.5 to 14.5 volts I would suspect the VR in the alternator.
  7. mkwl

    mkwl 2000 Club Member
    Messages: 2,362

    If it turns out to be the voltage regulator- will any harm be done by not addressing it in the near future. It doesn't spike a lot, stays well withing the "okay" area on the guage. seems to always spike "up" (to like 14.5 volts or so), not really down below 14.

    Can the regulator be changed out of th alt or would I need a new alt on the truck?
  8. highlander316

    highlander316 Senior Member
    Messages: 583

    just get a new alternator, if its bad. You can get a lifetime warranty w/ new ones. No real damage can be done if it's minimal, thats what fuses and stuff are for. The alternator charges the battery, if its slightly low or slightly high, it'll take a little longer or faster in either case. Bigger alternators recharge the battery faster. All electronics are drawn from the battery in some way, not the alternator.
  9. Burkartsplow

    Burkartsplow PlowSite Veteran
    Messages: 3,246

    my stepper motor is bad in my 04 chevy 2500 HD. they are replacing them
  10. mkwl

    mkwl 2000 Club Member
    Messages: 2,362

    What exactly did yours do, how'd you know it was the stepper motor? Was it covered under the warranty?
  11. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    mkwl Here a thread from a few weeks ago with the stepper motor info in it if it turns out that what the problem is: Gage cluster

    The voltage regulars don't die too often on the newer twin fan style alternators (like your truck uses). But GM doesn't consider these style alternators as a "repairable" component either. Replace the alternator as a whole if it needs it...
  12. mkwl

    mkwl 2000 Club Member
    Messages: 2,362

    I put my Dad's voltage/tach meter on it- reads steady at an idle at a hair short of 14 volts. The needle on the guage in the truck seems to only move up a little and "fluctuate" when I'm driving (engine RPM is up)- again though, doesn't move mnore than 1 or 2 "tick" marks about the 14 volt line.

    Could this be the guage that is no good?

    Is it common for hte guage to go bad and be just a "little off"?
  13. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Yep, and yep...especially on the 03-05 trucks.

    Did you hold the rpm's up a bit and check to see if it fluctuated on the volt meter? If it was still steady then but the gage in the cluster still "twitched" then it's the gage. They'll do that many times before they die completely. Can also work for a long time with the twitch and never totally die.
  14. wirenut

    wirenut Senior Member
    from nh
    Messages: 529

    just had mine done today at the old exeter chevy