Weird electrical problem

On my way home from work today, my turn signal fuse blew. Don't know why yet. But, When I was in neutral or I had my brakes on, my tach dropped down to zero. The engine was running fine. Any thoughts as to why?
Thanks
Dave

 

Just a fuse dude. Sometimes they go out. If it goes out again I'd look for a short somewhere. No turn sig no neutral no speedo is a fuse.

 

It is not the speedo that is down, it is the tach. I thought thatit worked off of a cable. Not electrical?

 

Tach cables can rust in half internally and quit like that. Take the cable off and pull on either end. If it comes out, you know you need a new cable. Dunno about the turn signal fuse. Might be two separate issues.

 

Tach on a 1982 XJ650 Maxim is electrically driven, powered by the flasher lights circuit (solid brown wire).

 

Thanks Chacal for that info. That makes sense, except that the tach works if I am in gear, but in neutral or if I hit the brakes it drops to zero. I am sure it is the fuse, but why would it work sometimes if it is electrical and the fuse is blown?
Thanks
Dave

 

Demons are infesting it. Perhaps an exorcist is available locally?

You may have a short somewhere in your system. Start at the fusebox (which you have upgraded, right?) and work forward from there.......

 

I have not upgraded the fuse box yet. Waiting for some money. But I guess now is the time. I did convert my rear turn signals into running lights. I will check those connections first.
Thanks for all the great help here.
Dave

 

Maybe I didn't read back far enough in the archives, but I am curious what the deal is with the stock fuseboxes? Haven't had any trouble with mine (yet)

 

The spring clips that grab the fuses are likely fatigued. One day one will just break off. There is also the issue of 25 years corrosion and that plastic box they snap into starting to fall apart.

 

sounds like a good enough reason for me. Anybody know what Chacals part number and price is for the upgrade?

 

Blade fuse boxes. Pretty common. Can do it yourself with inlines. They got whole set up at Local Napas and stuff. Converting is cake
-Chris

 

Carl is absolutely right, this happens. For no apparent reason, no warning. Pop open the lid and there is a tab laying there. If you want to break them all, try squeezing them together slightly to put more tension on the fuse. They'll either break when squeezed or when you snap the fuse back in.

On the 550, you will need to cut a good sized notch in the plastic tray where the old fusebox mounted and mount the new one to the top of the airbox.

 

here are a couple ideas i have for you from rescuing my 1983 XJ750 from the throws of the junkyard....

my fusebox was a BIG problem. someone quoted the fact that it is a 25+ year old part. Mine was falling apart, the blades holding the fuses break. even if they arn't broken they are introducing nore resistance into the electrical system. I pulled mine out of the bike altogether and have replaced it with inline Buss fuses - the yellow push together type. where i could any wire joint i made has been soldered together and covered with heat shrinks. On my bike i had a wire that the insulation was broken and the copper wire was broken in half. this was a BIG problem - more resistance due to less copper wire to carry the current. since i straightened it all out the bike has been fine. - also keep in mind that the bikes alternator dosn't produce power at low speed, it wan't the RPMs of the engine up to create the current. so at a stoplight you are running off the battery. I also had a battery problem and i replaced my battery with a GOOD sealed maintenance free unit. Don't cheap out or rely on an old week battery. Mine was $100 and was worth every penny. That was one of the best things i did to the electrical system on my bike.

Here is another thought i have. I am wondering what those 1157 lamps are doing to your electrical system. Here again, maybe you are introducing more resistance into the system - and if your bike is on the edge adding a few ohms here or there may be making the problem worse

 

OK, I will be replacing the fuse box with the inlines. Also, I was going to put of changing the back lights to LED's but maybe I will do that now as well. That should eliminate the 1157 current draw. Even thought I really haven't noticed any problems since I changed them out. My goal is to change the front signals to running lights as well and do the LED's there too. But I am having an issue with selecting the right LED's. I am concerned about visibility and brightness during the day.