Blowing Fuses - Signal & Ignition

Greetings!

Just did a swap of the right side control switch with a new OEM unit. Connected properly as far as I can tell, routing OK. First time I started the bike, everything was kosher. Several days later I went to start the bike. LCD came on as normal when the keyswitch was activated. I had to try multiple times to get the bike to fire. On one of those tries, the LCD went blank. Rode the bike with no problems, but no LCD.

Today I opened the fuse box. The signal fuse was blown. Also all of the fuses in the box are soldered in place... Previous owner was a bit of a jimmy.

Freed the blown fuse in the ignition slot. Pulled the 10A fuse from the ignition and placed it in the signal fuse holder. Turned the key, and the 10A fuse literally melted. I had to go up to a 25A fuse to get the fuse not to blow.

That 25A fuse blows immediately if I try to start the engine.


Very puzzled...

 

Very puzzled, and you're about to set fire to your bike! Do NOT stick higher-rated (amp) fuses into the circuit to "keep it from blowing". A blowing fuse means you have an electrical short, and you're going to have to find that short and repair it rather than trying to pump more electrons down into that leaking electrical pipe! Those electrons get HOT, very Very HOT, and you're going to cause more problems by attempting any type of "work-around".

The mere fact that the PO had welded the fuses into the box is indicative of past problems that someone attempted to repair incorrectly. It's just gotten worse since then, hasn't it?

You may have already burned up the LCD unit............

 

Looking at what is left of the fuse in the signal slot, looks like it may have been a 20A soldered in there from the PO. 8O

The higher juice fuses were just for quick test, certainly not for permanent use. LCD is fine.

What I'm trying to figure out is why juice going to the starter motor would pop the signal fuse in the first place. Seems like separate circuits, but the wiring diagram is a Greek rat's nest to me. Bike runs fine with the signal fuse pulled, as expected.

I'm going to walk back through the connections I disturbed since pulling the bike out of storage. My query was more whether anyone else had run into the particular electrical niggle of blowing the signal fuse when trying to start the bike.

 

Nope, and you shouldn't be either.
What year and model are you working with?
We need to look at the schematic for your machine, it might yield details as to what/how things are so messed up. Crossed wires are a possibility.

 

With fuses soldered in place I would be worried about melted wires and/or solder drip in bad places.

I think replacing the fuse box and looking for the short you have to have are in order

 

The bike is a '81 Seca 750.

Fuse box is a mess, I did have to fetch good-sized globs of solder out of the box. Plastic and hot solder don't mix well. Wires look fine, fuse terminals are all beat to crap, so I was careful with the isolation of them. It was suggested to me to eliminate the fuse box by going with four single fuse cases, like you find on older bikes. Evidently this fuse box style was crap from day 1, and now it is old crap.

I've found no weird splices or damage to the harness. When put away for the season last fall, all the electrics worked well. Bike was stored cold but out of the weather and with the battery removed. The seven main bulbs had been replaced last season, all sockets were good.

Suspect #1 is brake light switch in the replaced NOS right side control. Both wires on the switch were snapped, I soldered them in place on the stubs of the tabs but was unable to insulate them well due to confined space. The one time I ran the bike this spring with no issues was when the switch head was removed and the wires were capped. Since it is an open/close circuit, I did not initially think it could affect the system, but I will pull the plug as soon as I can get back at the bike.

Suspect #2 is the fuel gauge wiring. I had the tank and off several times, as it developed a leak over the winter in the dreaded low spot near the back. Terminals and sheathing look fine, but with many repeated removals of the tank maybe I damaged the wires inside? That should be as simple as unplugging the terminal I hope. The gas gauge won't work, but things like the neutral light and such should come on. Maybe?

I plan to invest in a little alligator clip/lightbulb current detector tomorrow. First stop I guess is the negative terminal of the battery & the main ground. Light comes on, I've got troubles...

 

PROBLEM SOLVED:

Went through the fuse box and cleaned out all the scrap solder. No joy. Checked through a few more connections. No joy. Unplugged the bar-mount brake light switch, *ding*. Managed to strip some of the tape away from the solder connection I made and it was grounding out on the switch. I dinked around with the switch, fried. Time to drop $45 at the dealer for an OEM switch, and I guess the XJ750 one is a single model item.

I suppose the moral of the story is use heat shrink wraps over wire repairs.

 

Hey Haz81, I do carry the correct switch for your 750 Seca, for a lot less than that..........!!

 

Haz81,

Chacal carries a fuse box that will cost you less than 4 inline fuse holders and has all the fuses included plus two spares. Fuse are the blade style rather than the old glass ones.

 

Glad you found it. I have Chacal's fuse box also - great replacement.