wires are melting!!!!

[SBTOM]

Hopefully someone can help me here because I am stumped! The background is that I just had to do a complete re-wire of the whole boat... literally every single wire with the exception of the motor harness. The PO used house wire and duct tape I moved my batteries (1 starter, and 1 deep cycle) up to the center console, as well as my fuse box, battery selector, and negative bus bar. 10 hours later, all of my accessories, lights, bilge pumps, etc. power right up...

BUT the ground wire leading to the igition melts within 5 seconds of turning on the battery selector (key on or off--- I pulled a noob manuever and tried twice!) I think that I have isolated the problem to something in the motor or trim system, but I can't figure out what would cause this.... At first I thought that it was the starter solenoid, but that seems to check out, and no fuses are blown. I disconnected the main power cable back to the motor and put in a new ground cable to the ignition. When I turn the key I can hear starter solenoid click to contact. As soon as a reconnect the power cable though, that ground cable is toast!!!

 

[bruceb58]

Re: wires are melting!!!!

Where does this ground connect? If you have this ground to your battery and the ground cable from the battery to the block is not on tight and have a good connection, all the current is going to be going through this one small wire. Somehow your grounds are not up to snuff. Its not this poor wires fault!

 

[SBTOM]

Re: wires are melting!!!!

I hadn't thought of that.... The way that I have it set up now, I have both of my battery grounds linked together and then tied into a bus bar, where all of my ground wires pickup. The main ground for the engine is connected to the supply bolt on one side of the bus bar. Should that be going directly to one of the batteries? Thanks-

 

[rbh]

Re: wires are melting!!!!

It does sound like a dead short, due to the fact that it only happens when you turn the key on
I would be looking for a wire that has been placed in the wrong position
pos on neg or neg on pos, or possibly one of your pos wires has shorted itself to ground through a hole in the insulation.
rob
and the noises you are hearing could be because you are back feeding power through another circuit?????

 

[SBTOM]

Re: wires are melting!!!!

well I only hear the clicking of the starter solenoid when I turn the key, but the negative will fry whether or not I have the key in the ignition... it goes as soon as I turn on the battery selector. If I don't connect the main power cable (running from the combine post on the battery selector back to the motor) then the ground wire stays in tact. If I do that,I hear the test beep for the temp sensor alarm when I put the key in, and then a clicking noise from the solenoid when I turn the key...

 

[rbh]

Re: wires are melting!!!!

like I was saying, you have a wire were its not supposed to be.
rob

 

[SBTOM]

Re: wires are melting!!!!

Thanks! I guess I just have to start digging and see if I got something flipped around.... I have my fingers crossed that I haven't done damage to the switchbox or the voltage regulator... I'm already waaaaay over budget on this project

 

[HappierWet]

Re: wires are melting!!!!

YUP, that's a short, or a bad battery

 

[slia67]

Re: wires are melting!!!!

What size is the wire you have going from the neg buss bar to the battery?

Edit:

I just re-read your original post. What do you mean the ground going to the ignition? You shouldn't have a ground wire going to the ignition switch.

 

[SBTOM]

Re: wires are melting!!!!

Well that could be a problem! There is a black wire coming out of the ignition, that I assumed was a ground. Looks like 18 guage??? I initially had thought that it should be tied into the ground for the instrument cluster (tach, speedo, fuel, voltage) but that fried the wire as well... what should that wire be connected to? Thanks guys, I appreciate the help!

 

[bruceb58]

Re: wires are melting!!!!

Out of the ignition switch?

Also, you have your ground hooked up poorly. You should have the ground cable coming off each battery bolted to the block. The bus bar can get its ground from either the block or the battery...your choice. By doing what you are doing, you have the entire ground current of the starter going through the bus bar. You are also adding two connections that don't need to be there between the battery and the engine. That is asking for voltage drop when you try to crank over the engine.

 

[SBTOM]

Re: wires are melting!!!!

I think that you are on to something there. By incorrectly wiring this I might have damaged some components at this point, but I guess that I won't know until I correct the wiring and test each part. Sorry to drag on the subject, but I really appreciate the help!!! Nothing really cements the learning like a couple of big price tags I'm gonna try to insert some photos (hopefully this goes better than the wiring). This first one is what I believe cause the whole system to come crashing down in the first place: mmmm toasty

I patched in new wires and fittings, and sealed everything up with glue shrink. From the marks on the crimp fittings, I think that the PO used vice grips as crimpers, and cut through his shrink tubes. After a while, there was contact and thats where the saga began.
Now, to get everything grounded correctly: The way that it is set up now, I have both negative terminals for the batteries linked and running back to a connection at the base of the starter motor.
http://s741.photobucket.com/albums/xx59/Radnar3/?action=view&current=IMG_0475.jpg
I did this simply because thats how the PO had done it... (maybe that was my first mistake) What I'm hearing is that there should be two seperate wires running from each negative terminal directly to the engine block, and that the starter, tilt, and everything else can ground off of that point? Here is a shot of the other ground point, just above the voltage regulator:
http://s741.photobucket.com/albums/xx59/Radnar3/?action=view&current=IMG_0476.jpg

 

[SBTOM]

Re: wires are melting!!!!

I don't know why that first one didn't work... let me try again:

 

[SBTOM]

Re: wires are melting!!!!

http://s741.photobucket.com/albums/xx59/Radnar3/?action=view&current=IMG_0472.jpg

 

[slia67]

Re: wires are melting!!!!

Oh my goodness! Yes, pictures are worth a thousand words.

First - Disconnect the grounds that go to the starter. You should have them connected to the engine block, as bruceb58 stated, seperately. Use an existing intake manifold stud if possible. That will eliminate the entire system ground going through your fuse block/ buss bar. (that can cause a lot of voltage drop especially if you have any corrosion in the furture)

Second - Dis-connect the ground going to the ignition switch. Your ignition switch works like most other switches. You should have one power wire coming in, then depending on the position of the switch, the switch will direct the power flow to different circuits. (i.e., starter, ignition system, assy)

 

[SBTOM]

Re: wires are melting!!!!

I think that I fixed the setup for my grounds, but somewhere in this re-wire project, I think that also I fried the voltage regulator. Not quite sure though... I found a thread on a 5 wire mercury voltage regulator and how to test it. The difference on mine is that it is a 6 wire regulator. Of course, the 6th wire is the one that does not appear to be functioning! It's one of two red wires... does anyone have a testing diagram for a 6 wire setup? is it even worth testing or should I just cough up the 160 bucks? Thanks!

 

[triumphrick]

Re: wires are melting!!!!

You sure have learned a lot at this point in the game, but it is never too late to get your hands on a basic 12v marine wiring manual. Just google it and buy the first one you see. There are many out there that will work, none much better than the other, but it sure would help for you to have this in front of you before you go any further.......good luck!

 

[SBTOM]

Re: wires are melting!!!!

Thats probably some good advice Triumphrick! I ordered the full service manual this morning, and I'm hoping to try and pick up a 12v bible this afternoon... Now if I could just figure out why the Merc parts fiche calls for a 5 wire regulator and I have 6...