Series 60 14l engine break switch issue

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Roadking96, Apr 7, 2026 at 7:58 PM.

  1. Roadking96

    Roadking96 Light Load Member

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    Hello everyone.i got 09 westernstar with ddec 6 series 60 14l.i changed out the engine break switch in the dash.after plugging in the new switch it blew the 5amp ENGINE FUSE(f33)and all the gauges quit working and the truck just cranks but won’t start.i try replacing it the with different switch but same issue.if i unplug the engine break switch everything works fine and truck starts.i did unplug the harness at the valve cover to see if something is shorting inside the valve cover but still same issue.anyone what could be the issue or where can i start to diagnose?thanks
     
    Last edited: Apr 8, 2026 at 1:51 PM
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  3. blairandgretchen

    blairandgretchen Road Train Member

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    What was the original issue that led to you replacing the switch?
     
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  4. Roadking96

    Roadking96 Light Load Member

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    The on/off switch cover had broken off
     
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  5. blairandgretchen

    blairandgretchen Road Train Member

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    You got me there. Was it an OEM switch ordered by VIN from dealer?

    I can't figure in my head why the on/off engine brake switch would cause the ECM fuse to blow.
     
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  6. Roadking96

    Roadking96 Light Load Member

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    Yes it’s from the dealer.i inspected all the harnesses from the outside to the inside for broken wires or shorts.but could not find anything.but when i plug in the engine break switch without the f33(engine)fuse i’m getting ground on one of the terminals on the fuse.so I’m guessing it’s shorting somewhere
     
  7. JB7

    JB7 Road Train Member

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    Post a picture of both the front and back of the switch. Also, a pic of the connector/wires that plug into the switch.
     
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  8. Roadking96

    Roadking96 Light Load Member

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  9. JB7

    JB7 Road Train Member

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    Make sure that the piece sticking out goes in the hole. See pics attached. It appears that the plug can be installed either way on the switch, one way of course is wrong. Does the back of the new switch (the terminals) match up with the old switch?

    upload_2026-4-9_15-20-55.png
    upload_2026-4-9_15-22-31.png
     
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  10. Roadking96

    Roadking96 Light Load Member

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    yes the terminals are exactly as the old switch.everything matches up.i checked the switch it only goes one way.there is like guide pin that goes into the slot on the harness plug
     
  11. JB7

    JB7 Road Train Member

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    Take a small punch or similar object and place it in the white hole of the old broken switch and see if you can operate it, moving it between different positions. If so, I would then plug in the switch, start the truck, and operate the switch and see what happens.
     
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