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
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.
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What was the original issue that led to you replacing the switch?
Roadking96 Thanks this. -
The on/off switch cover had broken offblairandgretchen Thanks this.
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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.Roadking96 Thanks this. -
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
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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.Roadking96 Thanks this.
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Attached Files:
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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?
Roadking96 Thanks this. -
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
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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.Roadking96 Thanks this.
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