wiring problem

[GotOne]

I have a switched power source running to the bow for an existing depth finder. Removed it and cut the wires and wired in a 332 and 3500 to the same set of wires. Both units work great-until I turn on my running lights, then the nav. light fuse blows. Put in new fuse and now the main 25 amp fuse blows-not the 5 amp in the fuse box. Put in a new battery and ran all wires except starting to new battery. Also. after I switched all the accessories and 332/3500 to the new battery and powered it up in the garage, no fuses blow. Today, out on Prior tried the lights-without the 332 or 3500 powered up and the main 25 amp fuse blows again. Anybody have any ideas? Thanks in advance.

[Giant_Jackpot]

I would say there has to be a short somewhere in the light wiring. The positive is touching a ground (metal) somewhere. Blowing 25 amp fuses is not good.

[GotOne]

Thanks for getting back to me. Where would I begin to look. The main power wire runs from the battery to the dash or fuse box. The only holes I drilled were for the gps receiver and to mount the 332 and 3500. I have a tourny Pro 175cs. I checked the wires by the fuse box, gps receiver andchecked the connections to the 332/3500. I did remove the slot for the front light to see if I could run the wires through the hole, but it solid-all the wires are on the bottom.

[18 inch Crappie]

It takes a good short to blow a 25 amp fuse. Follow the red or power wires from the battery all the way to your dash and anywhere else they go(front of the boat). Also make sure your battery is tied down, if it moves the Pos post may touch the side of the boat and short out. Something happend just need to find it. Good luck.

[Giant_Jackpot]

Most likely it is in the light wiring somewhere since the fuse blows when you turn on that switch. These can be tough to find if the wires are hidden in the gunwale. May have to fish new wires if you can’t find it. Is it possible your drill hit something?

[Valv]

The more I read it, the more it seems you possibly connected a negative in the wrong switch connector, which was intended to get a +.

Many switches have a negative pole for lighting when they are ON, check yours and be sure they are correct.

[GotOne]

Thanks all. I checked where I drilled and didn't see anything. Didn't change any wiring until the new stuff and the lights worked last year. I did find my positive wire for my auto bildge on the negative side with a blown fuse. I thought that might be the problem and moved it to positive when installed the new battery. 332 and 3500 run great until I put on the lights. Keep the thought coming. Tomorrow I will double check all the wires again. Thanks again.

[IndyEFI500]

If you don't have a voltmeter or know someone who has one, it might be easier to go to a service person. You could set a voltmeter to Ohms and put it in place of the battery and then start troubleshooting from there. I'm not an electrician but close enough and this is how I find all my problems. Can save a lot of fuses and troubles.

[GotOne]

I do have a voltmeter, however I only use it to check my batteries. It is easy to explain what setting on ohms and after that what should I do??? If it's not too much trouble.

Thanks

[Whoaru99]

Hmmm...

Almost seems like something in the fuse panel or switch panel is the problem if it's causing the main fuse to blow instead of a branch circuit fuse.

If you were working in either of those areas I'd be tempted to start there.

Didn't by chance drop a screw or a small bit of bare wire into the switch panel or fusebox when you were cutting/stripping/crimping in the new wires?

Oh, and even easier than using a multimeter is a plain old test light. Just remove the main fuse and connect the test light to the fuse holder terminals. The light will be off if there is an open circuit (or very small load), it will light up in varying degrees of intensity depending on the load, and will light up brightly if there is a short circuit.

Using the test light like this will save a bunch of fuses and maybe some wiring since the test light bulb limits how much current is in the circuit. Just note that some of the larger accessories may not operate because they cannot get enought power through the bulb, but this is just temporary for troubleshooting.

If worse comes to worse, undo EVERYTHING you did (including moving that bilge pump wire back where it was) and start over.

[GotOne]

I finally cooled down enough to look again. When I turn on nav light to the bow light, it lights up and so does the re-circulating pump. If I turn on the stern light the motor does not go on. I did try the light to the fuse holder and sometimes it lights up very dim and other times it does not light up. Any ideas for this mechanically challenged type guy. One other thing, when I turn on the light switch the radio speakers crackle for a second.

[Jeremy airjer W]

Its time to get out the volt meter. When a test light is dim there are two possibilities. 1 resistance in the wire before the test light (corrosion is the most common from what I see in the automotive world. 2. High resistance in the ground wire (again corrosion or poor connections). What you need to find out is if you have good power on all the positive cicuits and good ground on all the negative circuits. I'm guessind that starting with the light that causes the problems when it is on is a good place to begin.