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Alternator problems

Discussion in 'Truck & Equipment Repair' started by P.I.L.C., Feb 28, 2009.

  1. P.I.L.C.

    P.I.L.C. Junior Member
    Messages: 7

    I bought a 250 amp special purpose alternator for my 2004 F-250 powerstroke 6.0L. Took off my 110 amp stock alternator and switched them out, started it up and was charging at 17.2 volts. It tripped the circuit breaker for the electrical system, and all my guages went to the zero position as if the truck was shut off. I sent it back and he tested it and it tested fine he said. He replaced the regulator any way and sent it back again. Same thing when I got it back. I put it on a ford just like mine only newer, same problem. Do I need to reprogram my computer on the truck ( ford has no idea what is wrong either ). Has anybody ever ran into this problem with their ford?
  2. augerandblade

    augerandblade PlowSite.com Addict
    Messages: 1,054

    17.2 Volts!!!!!!!!!!!!!! isnt that too high, should be down at about 13.9 with all lights and accesorries on, heater wipers
  3. theonlybull

    theonlybull Senior Member
    Messages: 405

    sure they didn't send ya a 24volt alt, insted of 12v? kinda what it sounds like
  4. leon

    leon Senior Member
    Messages: 872


    The trucks computer will not help as the alternator is totally separate from it. It delivers power to the battery and then to the electrical system.

    Did they put it on a starter generator tester? You cant tell everything by sticking on a meter with a couple of alligator clips.

    the other thing that sticks in my mind is the battery- how many amps is it rated for? if you have a low amp battery that is a problem too.

    If they have a starter generator tester-that will tell you right away and if something is wrong with it.
    If I remember right those systems also charge another high output battery set too- my next thought would be a larger ciruit breaker-but check with the Ford folks first about the larger circuit breaker.
    Last edited: Feb 28, 2009
  5. P.I.L.C.

    P.I.L.C. Junior Member
    Messages: 7

    The batteries are a group 65 interstate battery ( 800 cca ). Im not sure what test the alternator shop put on the alternator the second time it got sent back. The batteries a 2 months old and test good. The only other thing I had to do was put a new wire from the alt to the bat. to compensate for the higher amperage. When I put the stock alternator back on everything works just fine.
  6. leon

    leon Senior Member
    Messages: 872

    alternating alternator

    I agree with auger and blade it has to be a twenty four volt alternator that was sold to you by mistake.
  7. unit28

    unit28 PlowSite Fanatic
    Messages: 6,634

    with the new Alt. your system is to hot.
    It would be nice if you could run with it, I can only think how bright your lights would be before they blew.

    Having a 24 volt alt would be the equivelant of 2 and a 6 volt would be 1/2.
    Now when you push the go peddle, you'll smoke something for sure.
  8. HomeBuilder

    HomeBuilder Junior Member
    Messages: 13

    There are a few possibilities. Does this truck have dual alternators? This was a common factory upgrade, and alternators must be sync'd with the computer. This is my guess, as the factory alternator works fine.

    The voltage is on the high side, but within spec for a typical 12 volt system, but are you sure you ran your auxilliary wire correctly?

    I upgraded the alternator in my truck last year to a 160 amp, and this seems fine for any amount of plowing I have done. It is my understanding that as you get more amps, you get shorter life from the alterntors due to heat, and 250 amps is a lot!

    Good luck, and keep us posted.
  9. theplowmeister

    theplowmeister 2000 Club Member
    from MA
    Messages: 2,617

    That is WAY to much voltage, you will blow bulbs and computers running that much voltage.
  10. P.I.L.C.

    P.I.L.C. Junior Member
    Messages: 7

    I got my problem figured out. With the new alternator came a new wire to replace the 8 guage factory wire. The ford shop told me that the stock wire went from the alternator straight to the battery. The alternator shop sent me a 2 guage wire to compensate for the higher amperage. So I bypassed the stock wire and hooked up the new wire. Apparently the stock wire does not go straight to the battery, it must stop by the ecm somewhere in the wire loom. Hooked both the wires up and it worked like a charm. Should of tried this on the first alternator 3 weeks ago before I sent the first alternator back. Well I guess they always say we learn best from our mistakes.
  11. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Follow the red wire. Take a guess where the alt gets its system voltage refrence from. ;)

    108786622 (Medium).gif
  12. unit28

    unit28 PlowSite Fanatic
    Messages: 6,634

    PD to Bat N to VR to alt?
    kinda blurry with my foggy glasses.