85 XJ700 - turn / brake / tach fuse - HOT HOT then blown

The turn signal/tach/brake/nuetral light fuse just started blowing.

I have done some reading and disconnected the brake pedal switch in my start to narrow it down. Then noticed that the fuse was hot to the touch, to hot to touch. And got hotter when engaging the turn signal (although it may have gotten hotter just due to the time taken to slide the turn switch.

I am not sure what info to all type down here, so I am thinking that I'll wait to respond to some questions.
You all are so great with the help and knowledge and attitude here! Any help is appreciated!



The following is unnecessary for the question being asked.
I have spent countless hours, into the wee ones of the night/morning pouring over the depth of amazing info and knowledge and experience in this forum. It is a treasure.
When I bought my bike, last summer, I didnt know a thing about the Maxim 700. Only that I was freshly divorced and could still afford it. $700 haha. I grew up on the back of my grandpa's Yamaha's and have always liked their looks.
Then when I needed to see why mine ran so poorly (like dog doo) I found this site and have been lurking ever since.

Thx to you all I have introduced my PayPal acct to XJ4ever and my savings account hasnt been the same ever since! lol. Seriously tho, so far just the $$ to offer up my Hitachi carbs to the altar at the church of clean. And then just a few hours ago: all I will need for a master cylinder rebuild, valve lash work (minus the shims since I dont know which ones I'll need yet) and Colortune plug. And I learned what carb sync is, sorry: ENGINE syncing (since we dont want to sync the carbs now do we? but to sync the power of our cylinders )
After getting the carbs clean, Clean, CLEAN, C-L-E-A-N (took me 4 times, ha) I loved this bike even more. The maintenance part is great therapy. Even tho I lost my garage in my divorce, that's what broke my heart lol. Now it looks like an impossible task of electric nightmares out in my office's parking lot, fun.

Anywhoo, thx to all those of you that make this forum happen and the community it has developed and the priceless quantity of practical, and highly technical, education it brings all the rest of us.

 

start by cleaning all the connectors and bulb sockets. Use dielectric grease and electric spray cleaner on all connections. Dirty connections increase amps use
signal fuse is 15 amps
signals using two 27 watt bulbs will warm up the fuse then add the brake light and 3 watts for each indicator bulb .

The turn signal/tach/brake/nuetral light fuse just started blowing.
or tach not workung when fuse blows
is your tach light

disconnect the horns to see if fuse still blows

 

So the fuse is getting hot, but do you know when is it actually blowing?

My suggestion to isolate the defect would be to disconnect the brake front and rear switch, the flasher relay assembly, and also the horns. These would be the most likely area, and the brake switches (usually front) have been known to inadvertently short to ground. If the fuse is no longer getting hot or blowing then reconnect one at a time and test the function. For example connect the rear brake switch and see if the fuse gets hot or blows, and if the brake light will illuminate when the pedal is depressed. After that connect the front brake switch and repeat the test. If that works depress the turn signal switch so no power is sent to the flasher relay, and then reconnect the relay. Check the fuse at this point since the 700 combines the autocancel and flasher relay, and the culprit could be the auto cancel portion of that unit. Then test the left and right signals for proper function. Lastly, connect the horns one at a time and check their function.

 

Thank you for the clear instructions. It all makes so much sense that I should have thought of it myself, auto wiring and electric has me felling like I'm stumbling around in the dark. So I appreciate shining some light on it for me.

 

OOoooo Puns.
You'll fit right in here.

 

I was all worried fer practically nuthin. I was envisioning an impossible troubleshooting nightmare...but it was just what you two said to do:

,

Armed with a bottle of spray cleaner (which I never would have given much credence too, learn sumptin new every third day) and systematically disconnecting the devices on that fuse, i.e. front brake, turn signal, back brake (this was the culprit!).

Interestingly, it wasnt blowing fuses anymore, it changed its behavior (before I found and fixed it, to be clear). The bike would die when triggering the brake light (while never lighting the filaments). Turns out they were dirty and greasy connectors inside the the tail light assembly. All they needed wsa a cleaning and rerouting up into that assembly to minimize future road grime accumulation. Along with healthy doses of di-electric grease btw.

Thank you for the help (especially for such a boring, garden variety prob)