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Author Topic:   Boat Lost Electrical Power
mdeture posted 10-04-2008 12:41 PM ET (US)   Profile for mdeture   Send Email to mdeture  
After my last lay up [of a Boston Whaler 170 MONTUAK] my [2004 Mercury 90-HP two-cycle motor] lost [electrical] power, and then lights and horn both lost power. When I reset the main the motor and horn each got power and now my lights and horn do not have power again though the motor does. Should I clean the ground terminals that enter a common bus? If I lose power, how do I tilt my motor to trailer it?
seabob4 posted 10-04-2008 02:35 PM ET (US)     Profile for seabob4  Send Email to seabob4     
Very interesting. You say you "reset" the main, which I am assuming is the main breaker, and power was restored. So the question begs, how did the breaker get tripped? Or was it not tripped, you purposely tripped it and then reset it? That would be useful info.

So now you have power to the motor, but no horn and lights. The motor receives it's "power" source through the engine harness and key switch, which is provided to the motor through your battery cables. So no power to your motor, I'd be looking at the backside of your key switch, and make sure your engine harness is securely plugged in, engine and helm ends.

Your "lights" and horn get their power from a feed from your main breaker to, hopefully, separate breakers feeding each function. Time to put a meter on your feeds and see where you have voltage. Check the condition of the terminals on the back side of these switches/breakers. Look for corrosion or loose connections. Sometimes, quick disconnects (some call them spade connectors) are not very tight where they grip the male connector. Work fine in a new condition, but crap gets in there and interrupts the flow of juice. Squeezing each rolled over side of the female connector with a needle nose can help a lot.

mdeture posted 10-04-2008 05:11 PM ET (US)     Profile for mdeture  Send Email to mdeture     
I lost power to the motor and everything and reconnected the battery after cleaning the connections (the battery had just been charged and I had reconnected it that day). When I was reconnecting the battery I say the main breaker and pushed it. Now everything works. After running my boat over to the slip, I notice my lights and horn now do not work. I had some water drip inside my console by a common ground bus so I looked at that today and they also looked good. I cleaned the battery connections and hooked them up, still no lights. This is a 2004 so it is all circuit breakers I think. I tried to bypass the breaker and test the horn and that did not work either. All the harness stuff is covered. Should I just continue using my boat with a portable horn and lights OR will this eventually cause me to lose engine power and be stranded? I would prefer fixing it. THe breakers look like little black rectangles about 1/2x1x1 inches with amp markings. It does not seem I have a breaker box just several stand accessories with their own breakers. Are these fed directly from the main breaker (but not the engine??)? Thanks, I am about stuck.
Chuck Tribolet posted 10-05-2008 12:27 AM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
seabob's advice to get a meter and start checking is the
right way to go. Start in the middle somewhere (the
individual breakers would be a good start. If you have
Measure from there to ground. If you have 12ish volts,
work towards the horn. If you don't, work towards the


mdeture posted 10-05-2008 12:37 PM ET (US)     Profile for mdeture  Send Email to mdeture     
So the main breaker was tripped and upon reset everything re-powered except the navigation lights. I am getting power to my anchor lights on the same circuit as the navigation lights (rocker switch), but I cannot get the navigation lights to turn on though the rocker lights up in both positions. I did pull the wiring diagram and used a meter so I feel like a little bit less of a yahoo. I appreciate the help.
seabob4 posted 10-05-2008 03:30 PM ET (US)     Profile for seabob4  Send Email to seabob4     
The "indicator" light for your navigation lights tells me you have good power going to the switch, as well as a good ground. The indicator lights need that ground, your switch does not. Now, turn on your navigation lights, and see what voltage you have on the bottom terminal. If you have decent voltage, it's either the wiring going forward, or probably your starboard navigation light. The port light typically is piggybacked downstream from the starboard. If you don't have voltage at the switch, time to see what's going on there. Could just be a loose connection. Remember the quick disconnect advice.
jimh posted 10-06-2008 08:39 AM ET (US)     Profile for jimh  Send Email to jimh     
[Moved this discussion of a small boat electrical system to SMALL BOAT ELECTRICAL from another area.]
jimh posted 10-06-2008 08:48 AM ET (US)     Profile for jimh  Send Email to jimh     
There is a recent concurrent discussion on the topic of problems with the navigation light rocker switch on a newer Boston Whaler boat. See

mdeture posted 10-06-2008 09:52 AM ET (US)     Profile for mdeture  Send Email to mdeture     
Thanks for all the help!
K Albus posted 10-06-2008 03:29 PM ET (US)     Profile for K Albus  Send Email to K Albus     
I have had this same problem with the navigation lights on my 2002 Dauntless 180. When the navigation lights are switched on, the dash panel switch is lighted, and the rear all around lamp is lighted, but the front red/green lamp is not lighted. The problem is caused by corrosion on the light bulb and/or the contacts in the front light fixture. In my case, it is a recurring problem. I just take off the light cover, clean the contacts, and put it back together. It seems I have to do this about once a year.

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