First, verify that the fuse that you are replacing has the correct rating. Someone could have easily stuck a 10 amp fuse in a 20 amp slot, because that's all they had. If the correct fuse is 10 amps for example, do not put a 20 amp fuse in the slot, hoping to cure the problem. You don't have some kind of electrical accessory that would be on while the signal lights are on, that is connected to the signal light circuit. If you do, the accessories load combined with the signal light function could exceed the fuse rating. If this is the situation, you'll probably need to find another circuit to connect your accessory to.
If that doesn't do it, make sure that all of the bulbs are the correct bulbs. I think that they all should be 1156 or 1157. Check a manual to be sure. Also, make sure all of the bulb sockets are free of anything that could short something out. If everything there is all right, try changing the flasher. I think that they are only a few dollars. It should just plug into the fuse block.
If all of that doesn't do it, you need to check the signal light switch. There is a possibility that it is causing the short, but I wouldn't think that would be very likely. I believe that you will have to remove the steering wheel to get to the switch.
If everything checks out, the short is probably somewhere in the wiring. You'll basically need to check all of the connections and all of the wiring that you can get to. You may be able to narrow the wiring that you need to check down though. Does the fuse blow when using the signal lights in both directions, or only one direction? If its only in one direction, we'll say left for example, you will only need to check wires that pertain to the function of the left turn signals. If the fuse blows in both directions, the problem is likely somewhere between the power supply and the switch, not in the wires going out to the lights themselves.
400 Small Block
Trick Flow Heads
Comp 282S solid cam
Performer RPM intake
750 CFM Holley
and a Muncie four speed
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