Polarity reversed - now what? HELP

[Sea Ray Vega]

Hi Guys, I've got a problem today! While rehabbing my new (to me) boat I removed the starboard engine/house battery to replace it with a new one - problem is I didn't pay attention enough to notice that the previous owner had replaced the ground wire with a RED cable, and the other one was black. So when I hooked it up there was a big spark - once I noticed the polarity was reversed I changed it back to the way it should have been wired, but apparently too late. Now I've got no power anywhere, and the AMP meter for the starboard engine is pegged. Have I totally fried my boat, or can someone please advise me as to how to remedy this situation. For reference it is a 1975 Sea Ray Sundancer 240 with twin 140 hp mercruisers.

Please help if you can!

Thanks,
Vega

 

[boat1010]

Re: Polarity reversed - now what? HELP

First of all welcome to Iboats. There should be a fuse somewhere that has blown. Just follow back the wires and see if you can find a fuse.

 

[SBTOM]

Re: Polarity reversed - now what? HELP

I recently pulled a very similar maneuver. After replacing a voltage regulator, an ignition switch, and a few assorted wires, it was good as new. Hopefully you were protected by the blown fuse, but if you weren't, my advice would be to take your time troubleshooting. I charged into my project without fully understanding how the system worked and it cost me a lot more money than it should have! That being said, there are a lot of really knowledgable people on iboats, so with little coaching, you'll get through it. Also, the service manual is definitely worth it if you don't already have it.... just avoiding one fried component means that it has already paid for itself.

 

[Sea Ray Vega]

Re: Polarity reversed - now what? HELP

Thanks! Perhaps someone could be so kind as to give a hint where said fuse may be, or what it looks like? I don't see anything fuselike.

Vega

 

[SBTOM]

Re: Polarity reversed - now what? HELP

Disconnect the batteries before you start doing anything!!!! If you have lost power to literally everything, then you probably have more than one blown fuse, or it is a more involved problem. If the wiring is fairly origional, you might as well start looking for in-line fuses (picture a little plastic or rubber pod about the size of a AAA battery--- wire goes in one side and comes out the other) Open those up and if you notice that the wire filament inside of the glass tube is broken, then they are fried. If the wiring has been updated, you might be looking for a fuse box with a series of blade fuses. (picture a small plastice box with two rows of yellow, blue, or green fuses. they'll say 10-15-20-30 etc...) Along the way, if you notice that any of the wires are worn, or if they make a crackling noise when you flex them, then that could also be a problem. If you get back to the engines and you haven't found the problem, then your best bet might be to start a post on the Mercruiser forum... might be fused on the engine end of the harness...

 

[Silvertip]

Re: Polarity reversed - now what? HELP

If you lost power to everything, that indicates this is NOT a multiple circuit problem and none of the fuses in the fuse panel are probably blown. What is tripped is the circuit breaker in the engine bay. Follow the postive battery cable to the engine. it should terminate at either a large fuse or a circuit breaker with a reset button on it. Push the button to reset it or replace the fuse if that's what you have. Now -- what you could have done is fried the alternator which is why the ammeter is pegged. And are you sure that's an ammeter and not a voltmeter? An ammeter reads -30 0 +30 or similar numbers while a voltmeter reads in a range of 10 - 18 (volts). The fact that there were TWO red cables should have been a clue to determine which one is ground.

 

[Sea Ray Vega]

Re: Polarity reversed - now what? HELP

Yah, It's an Amp meter -30 zero +30 and the gauge points down on the peg about where +90 would be. Big circuit breaker I see isn't blown the button is pushed in. Something I read said to look for a fuse block, what might that look like? Oh, and more like 5 red and 4 black cables....and the actual positive cable to the solenoid is BLACK.

 

[rspar]

Re: Polarity reversed - now what? HELP

I'm not sure that the black and red battery cable thing is unusual my boat has that. I had to stare at it for a minute but came to the conclusion that black isn't always the positive but red always is at least in my experience. I did look away though:redface: