2 Trailer Plugs?

Discussion in 'Trucks [ Eighteen Wheelers ]' started by Juicehauler, Dec 28, 2013.

  1. Juicehauler

    Juicehauler Light Load Member

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    Wondered this for a while but never asked till now, why do some tractors have 2 7 pin trailer light cords?
     
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  3. DL550CAT

    DL550CAT Road Train Member

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    For dump valves, back up/work lights, and stuff like that.
     
  4. GrapeApe

    GrapeApe Road Train Member

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    Our car haulers have 2. They have a suspension over lift (electric solenoid), electric back up hydraulic pump and safety strobes for loading. not enough wires in the 7 way.

    Other uses could be dump valves, lift axle, extra lights, scale system, etc. Basically anything extra that you want to control from the cab or if you're going to overload the aux circuit.

    We have a few with 4 airlines too. The older suspension lifts were just air, so an extra line for that, and some have a sliding king pin rather than a sliding 5th wheel.
     
  5. truckman29801

    truckman29801 Medium Load Member

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    I must ask the same question, one ive been using on the green cord ..........the other cord is yellow and labeled Stay-dry- ABS or something, ill look 2maro but my normal electric line wouldn't plug in because one pin is big in the socket hole. i might post a pic as well.
     
  6. Richter

    Richter Road Train Member

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    At TMC trans we had 2. They used the center pin on the main (green) line to control the trailer dump valve. This is normally used for ABS. The installed a second wire (yellow) to power the ABS since the wire that should be ABS was used for dump valve. Why they dont just power the dump valve with the yellow, I do not know. That is probaly why your yelloe is labeled ABS. With a standard wired trailer your ABS should still work off the green wire if the dump valve switch is in the on position.
     
  7. truckman29801

    truckman29801 Medium Load Member

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    IM LOST this truck has never pulled a dump axle or lift axle it doesnt have a dump switch either, Ive never used the STADRY-ABS plug port View attachment 60008
     
  8. Richter

    Richter Road Train Member

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    Well then your truck manufacturer prob wire the abs into just encase.
     
  9. Juicehauler

    Juicehauler Light Load Member

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    i pulled out the test light on the abs plug, only 1 live pin with the key on, and the top ground pin is a female socket and the rest are typical male pins, ive never ran into this style connector before. Probably just take it out, havent ever needed it, prob never gonna need it.
     
  10. Juicehauler

    Juicehauler Light Load Member

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    Now i just need to figure out where the wire for my aux pin ends up in my dash(01 pete 379), should be fun, i traced it as far as the where it comes through the firewall, then it just disappears with the rest of the maze of unmarked white wires. prob just end up tying in there and running my own wires
     
  11. truckman29801

    truckman29801 Medium Load Member

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    yeah it came from Freightliner like this, i really wish I knew why they did this.
     
    Last edited: Dec 29, 2013
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