Te fuse keeps blowing when i put my truck in reverse

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It is likely to be the reverse switch that activates the reversing lights, or frayed shorted wires in the trunk.

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Possibly an internal failure of the reverse switch. The blown fuse is for both the reverse and the turn signal lights. The fix is replacement of the reverse switch.

You have to isolate the wiring harness that goes to the reverse light.

Somewhere in that path a chafed or bare wire is grounding out and blowing your fuse when you put the car in reverse.

You can rule out internal transmission wires. The only thing I know of would be the reverse light wiring. You have one power wire to the neutral switch. So when the lights are supposed to come on the fuse blows the turn signal . You said you check the wiring, Did you check for continuity? High resistance cause a higher amperage draw. Also did you check the hot wire for short to ground? Try leaving the engine off. No lights on. Put it in reverse, see what lights come on. Have someone stand in back and watch as you put it in reverse. The lights should flash for a split second before the fuse blows. If any other lights come on, you have lost ground to the reverse lights.

A bad outside mirror motor will also cause that fuse to blow. Is your fuse blowing when you adjust the mirrors or when you put the car in reverse? If yes, then the mirror motor is the problem.

Unfortunately, many possibilities. If you have time, start by removing both reverse lamp sockets from light assembly(and keep from touching any metal), remove bulbs from sockets, CAREFULLY INSPECT sockets and wires. New fuse of correct rating. Turn key on and try again in reverse.
Fuse still blows: Next place to look is transmission reverse electrical switch and wiring as far as you can trace looking for burned/stripped wires near transmission and wires by sockets
Fuse doesn't blow: Turn key off and install one lamp in socket at a time. DO NOT install sockets into fixture at this time. Test. Remove first lamp to check second. If still O.K., each socket back into fixture(one at a time same as before)and test. Most common problems: Sockets contaminated, wires shorting at sockets, bulbs installed incorrectly shorting to ground.

hi
check the wire because if the fuse keep blowing there's a wire somewhere on the car that has contact with the frame so everytime you put your car on reverse the 12V wire shortcut on the frame so the fuse blow check all your positive wire and your bulb as well
Good luck

replace the transmission park neutral switch.its probably shorting out.

Sounds like you have a wiring problem. May want to begin by determining which circuit is causing your fuse to blow. If you are not mechanically inclined, I recommend you take if to a trust worthy repair shop.