Thermo king Unit Code 25

Discussion in 'Refrigerated Trucking Forum' started by rasymacmac21, Mar 16, 2015.

  1. rasymacmac21

    rasymacmac21 Light Load Member

    291
    155
    Sep 25, 2009
    East of the Mississippi.
    0
    I'm getting code 25 (alternator check) on my TK SB 3. Alternator was replaced recently. Every time I start it up, it shuts down and I have to restart it a couple of times until the amps reach above 0 so it can stay on. I tried cleaning the grounds, battery and cables, and the same thing happens. Any one knows what it might be?
     
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  3. EZ Money

    EZ Money Road Train Member

    Code 25 is for the alternator so if it was already replaced either you got a defective one or possibly the battery has a bad cell.
    I would pull the battery and have it load tested.
    Do you know if that alt. has a built in regulator?
     
    Oldironfan Thanks this.
  4. rasymacmac21

    rasymacmac21 Light Load Member

    291
    155
    Sep 25, 2009
    East of the Mississippi.
    0
    It has a built in regulator. It stays on after I go through that hassle a couple of times. Maybe something else that's corroded would drain the amps from the start. Probably gonna have to take the alternator and battery out and test it before I go any further I guess.
     
  5. 404a

    404a Bobtail Member

    23
    11
    Feb 28, 2015
    Delavan, WI
    0
    On this unit it is not uncommon for the shunt on the board to go bad. If your battery was bad that would not affect the units code 25, these units could run with the positive cable completely off. My bet is on the shunt on the board. This is assuming all connections are ok and the alternator is ok. You should have about 14.1v at the main positive cable on the alt. The voltage in the plugs on both terminals should be about the same when disconnected.
     
    Oldironfan Thanks this.
  6. ReferDude

    ReferDude Bobtail Member

    1
    1
    Aug 30, 2018
    0
    My unit starts out with 20 amps in a matter of seconds it drops to zero amps, help
     
    Oldironfan Thanks this.
  7. reeferwrencher

    reeferwrencher Medium Load Member

    552
    1,469
    Aug 4, 2018
    0
    It should stay just slightly above o amps after running for a bit.What is the voltage reading and is the reefer shutting down or getting a code?
     
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