03 ford f250 7.3 power stroke keeps blowing turn signal fuse.

the turn signal circuits are shorted,,the fuse blowing saved you from a fire.(burning harnesses)
faili on left or right or both and HAZARDS? SORRY 3 fuses to learn that.
USA answers, Chevy S10 only
there are 2turn fuses, I see, in the schematics.
LT-turn and RT-turn, so now you know which side is shorted. just a glance and bingo , side. bad know, cutting work in ;1/2.
but, there is 10amp turn fuse too, that runs the turn flasher module
so 4fuses, turn left and turn, main and haz main.
this is bad.

any thing in this whole turn system can blow fuse turn main, BLK.
but learning if only one side fails ,is great moment,
if both fails, the problem is this module or the turn swtich is shorted.

first thing i guess to understand what is going on here ,is a little back to basics on how turnsignals work , first item you have is power fuse then it's off to flasher module than it goes to the turnsignal switch on colum ,of course anywhere on it way to there the power could got to ground and cause the fuse to trip, now the power depending on Left or right selection , is directed to lights on both front and back of truck,thankfully rangers don't have em on the side) now any place in this pathway the wire could go to ground and blow the fuse, now to troubleshoot and narrow down the area that fault is located , (1) replace fuse with correct size and ck for proper fit in fusebox and start and operate truck for a few minutes DO not use turnsignals, ck fuse is it still good if so go to step 2 if not stop and ck wire conditions in steering colum and switch(2) start truck and try right hand turn signal only verify lights working ,Ok yes/no if not replace fuse and try left side same way, Ok yes /no if right or left side only blows fuses take ALL bulbS OUT of lights and try again , if fuse still blows then look for wire fault on that side of truck if fuse is still good then look carefull at light bulb sockets for rust and powered corrosion (ill bet an 87 has some ) you may need to replace bulb sockets , they do sell em in autoparts stores .

If you keep blowing the brake fuse than you have a short in the system. Unplug the brake switch. Install a new fuse. If it did not blow than the problem is after the brake switch. Next unplug the turn signal switch, then plug the stop light switch back in and press the brake pedal. Did the fuse blow. If not than the wiring is good in between the two switches. With the turn signal switch disconnected use a jumper wire in between the light green wire (power from the brake switch) and the orange with light blue wire (power to the right brake lamp). If the fuse blows than there is a short in the right side brake circuit between the plug in and the rear socket assembly. If the fuse does not blow than jump from the light green wire to the Light green with orange wire (power to the left brake lamp). If the fuse blows than the problem is in the left hand brake wiring circuit.

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you have a wire with power grounging out somewhere in the wire for the turn signals

A mechanic would disconnect the turn signal switch and check the circuits for shorts to ground.

Go to your fuse box in the engine compartment. Check the fuses in the box. Your turn signals and brakes to your trialer are controlled fron fuses in that box not inside the truck!

Replace the signal Relay thats your problem.

It sounds like the fuse is doing what it is supposed to do, and burning out when there is a short circuit. Check the wiring from the fuse block back to the lights and pay special attention to the trailer connection.

diconnect the heater, if it doesnt blow fuses anymore, the heater may be shorted out.

you probably have a short somewhere within the power line if the fuse keeps blowing put a green 30 in and see if that fixes it if not then you need to find out where the short is..it is almost impossible you will probably have to taker it to a dealer...hopefully the biger fuse will work..good luck