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Mysterious Low Voltage Issue

Discussion in 'Western Plows Discussion' started by mtnxtreme, Feb 1, 2015.

  1. mtnxtreme

    mtnxtreme Member
    Messages: 55

    I leave my truck plugged in with a battery tender, I turn the key on the gauge reads a little more tha n 12V , I start it up I get a 14V reading,and it works fine for abt. an hour, after abt. an hour I start having trouble where it won't lift, just whines but won't totally engage and lift, the gauge reads a little more than 12V, if I turn off the truck it starts right up like the battery is fine, still won't lift though, if i let it idle for like 15 minutes the gauge now reads 14V and I can use the plow. Same scenario every time I use it, when I first start it up it works fine. Any ideas, battery, alternator ??
     
  2. xgiovannix12

    xgiovannix12 PlowSite.com Addict
    Messages: 1,419

    Have the battery load tested
     
  3. mtnxtreme

    mtnxtreme Member
    Messages: 55

    I was thinking that, maybe its having trouble holding a long term charge ?
     
  4. xgiovannix12

    xgiovannix12 PlowSite.com Addict
    Messages: 1,419

    Prob dropped a cell
     
  5. mishnick

    mishnick 2000 Club Member
    Messages: 2,243

    If it starts the engine the battery may not be at fault. Look for loose or corroded connections on the battery terminals, check the grill plug with the two big pins and the plow motor connections.

    Of course you would be wise the do a battery load test and an alternator output test. What confuses me is that the starter motor certainly needs as much or more power than the plow pump motor so if it cranks OK and starts then why won't it lift the motor.
     
  6. mtnxtreme

    mtnxtreme Member
    Messages: 55

    I know it's strange and looking at it more closely whenever I hit my plow controls the gauge drops below 12 volts, to like 10 volts and it does the same when I beep the horn, but the truck starts every time.
     
  7. mishnick

    mishnick 2000 Club Member
    Messages: 2,243

    What generation of plow is it? Three plug or two, uni, ultra? It may be that the fusable long feeding your fuse box, voltmeter and plow ignition wire is failing and, depending on plow version, there is not enough voltage to the controller to close the motor relay.
     
  8. Sprag-O

    Sprag-O Senior Member
    Messages: 220

    Have the alternator or battery tested.

    I'd suspect the battery is alright, and that's why the truck performs alright in the beginning. Alternator can't keep up and eventually the battery starts losing power. Then the alternator can't keep up at all. Let is sit, with the alternator doing nothing but charging the battery, and you have your reserve back.

    I'd test the battery since it's easier to pull, but putting the alternator on a bench tester would be my next suggestion.
     
  9. seville009

    seville009 Senior Member
    from CNY
    Messages: 733

    I had a problem a few weeks ago where my truck with an mvp basically shut itself down. Turned out to be overheating plow wires. This is the thread - look at the last post for what the dealer replaced. Everything has been fine since it was fixed. Not sure if this is your issue, but you never know.

    http://www.plowsite.com/showthread.php?t=159932&page=2
     
  10. Sprag-O

    Sprag-O Senior Member
    Messages: 220

    OP says it even happens when he hits the horn. Not sure it's plow related.
     
  11. seville009

    seville009 Senior Member
    from CNY
    Messages: 733

    He posted it in the Western Plows forum instead of one of the truck specific or other forums, so the conclusion is that he thinks it's plow related.
     
  12. mtnxtreme

    mtnxtreme Member
    Messages: 55

    It's a Uni Mount with 2 pin heavy plug and 9 pin small plug, Mishnick concluded in a previous thread of mine it was an Isarmatic relay style ? Yes I posted in the Western section thinking maybe it was maybe a Western issue like a wire that would go bad and then start making a heavy draw on the system, but then I noticed the gauge showing the same heavy draw even when beeping the horn, so possibly the alternator charges but then with a heavy draw it craps out ?
     
  13. mtnxtreme

    mtnxtreme Member
    Messages: 55

    After looking into it, my battery is in good shape, I forgot its only a year old, if I drop a new alternator in it do you guys think 100 amp is enough ?
     
  14. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,924

    No...bigger the better
     
  15. mtnxtreme

    mtnxtreme Member
    Messages: 55

    Bigger than 100 amp, I think stock is like 45, what do suggest.
     
  16. mishnick

    mishnick 2000 Club Member
    Messages: 2,243

    The uni relay takes power from the ignition wire feeds the motor relay and coils. So if the horn drops the voltage it could be a bad connection downstream from the battery.
     
  17. mtnxtreme

    mtnxtreme Member
    Messages: 55

    You mean where the main plow wire hooks to the battery?
     
  18. mishnick

    mishnick 2000 Club Member
    Messages: 2,243

    No, there is a red wire that comes off the controller harness about a foot back from the controller plug under the dash. It will go to an accessory fuse in the fuse box.
     
  19. mtnxtreme

    mtnxtreme Member
    Messages: 55

    So your saying check that for bad connection ?
     
  20. mishnick

    mishnick 2000 Club Member
    Messages: 2,243

    What I am saying is test for a bad connection between the battery + post and the fuse box. Depending on what kind of truck it is there will be a fusible link somewhere between the battery + and the fuses that could be on the verge of failure. A fusible link is special piece of wire, usually about 6 inches long, that acts as a high amperage fuse. Fords have one for the alternator and one feeding the main fuse box. They are usually on the + lug of the starter relay and often well hidden inside split loom or taped up. On GM they are usually on the starter where the main wire from the battery connects to the solenoid. The point is that they are always after the starter so they don't effect the starter. You talk about your gauges and your plow control failing while your voltmeter drops from 14 to 12 volts. These are all indicative of a voltage drop on the feed to your main distribution point... which is the fuse box right where you plow controller is plugged in... Buy a Haynes or Chilton manual for your truck and look at the electrical schematics under starter and charging system or whatever shows the main feed to the fuse box. Look for the fusible links. There is where you will find your bad connection.