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Discussion Starter · #1 ·
Someone posted a wiring diagram in 2020 for a trx400fa. I have a 2006 and it keeps blowing the 15amp fuse when I hit the hand brake switch. I replaced the brake switch first with no luck. I cant find any rubbed wires. Have disconnected the rear lights to eliminate the bulbs. I am at a loss without a schematic. Could you share the one you posted?
 

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I have seen chaffed wires, defective speedos, CDI's, faulty alternators, defective fuse clips and bad grounds cause blown fuses. I only know a few ways to find what causes a fuse to blow; first I disconnect all electronic components (rec/reg, speedo, CDI unit, fuel sending unit, fuel pump, all lights etc. Then with the key on install a new fuse - if the fuse blows, disconnect more components if any - if none, replace the fuse with a piece of wire and see what starts smoking. Remember, the fuse is to protect the wire. If there is a short in the wiring, the shorted wire will get hot and the insulation will start to melt, but only up to the point of the short to ground, but if two wires are shorted together, both will get hot. Find where the one color is shorted to the other color and separate them. A trick I use is to pull a single strand of copper from a lamp cord to take the place of the fuse. Being smaller than the wires themselves, it will get hot and glow perhaps even burning into before there is any damage to the wires. If the fuse does not blow with things disconnected, start connecting things - when you connect a component or unit and the fuse blows, then you have found the defective component.
 

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Discussion Starter · #6 ·
My problem is it doesnt low the fuse quickly. the last time I had to ride it for at least 15 minutes and the only way I know its blown is the dash does out. I guess I'll have to disconnect things in the circuit, ride it and see if I can get it to blow to eliminate things. Was just hoping for the magic arrow. lol
 

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OK - up the fuse size by 2.5 or 5 amps - it will still be safe for the wiring and may expose the culprit unless it's a bad ground and then the same thing might happen, but just take longer
 

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Discussion Starter · #8 ·
OK - up the fuse size by 2.5 or 5 amps - it will still be safe for the wiring and may expose the culprit unless it's a bad ground and then the same thing might happen, but just take longer

Getting back to this finally. I appreciate the wiring diagram but have a question. I'm used to working on cars and the wiring diagrams fuse blocks match what is on the cars. The one you sent me. The fuse order isnt the same. Is that normal or ok? I've traced all of the wires again and cant find anything. I've attached a pic of my fuse block cover for reference. The 15amp light fuse is the one blowing and it will only blow if I am riding it for a little bit. The only way I know its blown also is the dash goes out
Fluid Automotive lighting Gas Font Automotive exterior
 

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Motorcycle and ATV wiring diagrams don't match the physical location of the component.

I guess my first question would be have any of the light been 'upgraded' to higher wattage? If not, check for poor grounds and try upping the fuse slightly to see which wire gets hot. Don't discount the possibility of a poor connection on the fuse itself. I've seen many faulty fuse blocks and or panels.
 

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Discussion Starter · #10 ·
Motorcycle and ATV wiring diagrams don't match the physical location of the component.

I guess my first question would be have any of the light been 'upgraded' to higher wattage? If not, check for poor grounds and try upping the fuse slightly to see which wire gets hot. Don't discount the possibility of a poor connection on the fuse itself. I've seen many faulty fuse blocks and or panels.

Finally got it to happen in the shop. Not sure why today was the day but as soon as I put a fuse in and hit the brake it blew the fuse. Put my short detector in and started searching for the dead short. Traced it back to the rear brake light switch. Hit it will a hammer a couple time and the short went away. Hit the brake and it was back. Thanks for the help
 
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