no jake brakes

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by hodge63, Apr 26, 2020.

  1. hodge63

    hodge63 Bobtail Member

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    Apr 25, 2020
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    i have a 1996 freightliner fdl 112 with a cummins m11, the jakes don't work. I just bought it for a grain truck, am I over looking something, another switch to activate,ect. we have jumped them and they kick on so I know it is a wire problem. there is no power at the terminals on engine. all switches are doing what they are supposed to. Where does the power go after the switch? could it be a faulty relay? If so where is it located? or a ecm problem, it has no engine codes either.
     
    Last edited: Apr 26, 2020
    Deere hunter Thanks this.
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  3. lwlevens

    lwlevens Medium Load Member

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    Is the clutch pedal up all the way. Mine wasn't coming up all the way on it's own and Jake's weren't coming on.
     
  4. hodge63

    hodge63 Bobtail Member

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    Apr 25, 2020
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    yes that switch works, shuts down cruise and fast idle like it is supposed to.
     
  5. Rideandrepair

    Rideandrepair Road Train Member

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    What about the brake switch? Should do the same thing.
     
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  6. hodge63

    hodge63 Bobtail Member

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    Apr 25, 2020
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    well it seems to do the same as clutch switch, by shutting off cruise and hi idle when pressed
     
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  7. wtokhi

    wtokhi Light Load Member

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    did you check the jake solenoids
     
  8. hodge63

    hodge63 Bobtail Member

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    Apr 25, 2020
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    yes we hooked a power lead to them and they both kicked on
     
  9. stillwurkin

    stillwurkin Road Train Member

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    I have to have the fast idle or cruise switch off in order to engage the engine brake while driving with my foot. Now if driving with the cruise, with engine brake switch on, it will engage the engine brake if momentum pushes me 2 or 4 mph over my set cruise speed.
     
  10. hodge63

    hodge63 Bobtail Member

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    Apr 25, 2020
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    k I will try that tomo, thanks
     
  11. Rideandrepair

    Rideandrepair Road Train Member

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    FC49811B-7CE2-4AFA-8F22-8382796270D9.png
    It should be good then. Neither of the Jake switches working, cant be 2 bad switches. My Freightliner w/ Detroit has a plug above the starter for jakes. Maybe the wiring is broken somewhere.Heres a pic of it, (unplugged).
     
    lwlevens Thanks this.
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