300SE Wiring Diagram

TeamPCBeach

Seaman
Joined
Feb 10, 2011
Messages
73
Anyone have an idea where I can get the electrical/wiring diagram for a 1999 300SE? We have a couple of things that just don't make sense to us.

1) Even with all three battery switches in the off position, the AM/FM radio still gets power. Although it is just a small draw for the memory feature of the radio, if our boat sits for more than a month, the STBD starter battery is dead. The radio is wired through a fuse panel so I can remove the fuse, but we often forget. Also I would think the radio should be wired to the house and not the starter battery. This isn't a big deal as the boat generally does not sit this long except in the winter when we only get to run it about once a month.

2) The boat has a battery isolator, but it looks like the isolator is only tied to one engine and not to all three batteries. I think it should be tied to both engines and all three batteries.

Thanks in advance!

Phil
 

bannister

Petty Officer 2nd Class
Joined
Oct 17, 2009
Messages
165
Re: 300SE Wiring Diagram

The radio always gets power for the settings and radio station memory.
The connection is at the same point as the bilge pumps that also always have power for security reasons (Not sink after a heavy rain for ex).
Those connections are usually in the 12V distribution box in the engine compartment.
If you store or leave the boat for a long time unattended, you should always remove the negative pole of all batteries.

You can always ask for the wiring diagram at the factory by simply email them a request.
 

TeamPCBeach

Seaman
Joined
Feb 10, 2011
Messages
73
Re: 300SE Wiring Diagram

Bannister> Thanks for the reply. The bilge and radio are tied to the 12V distribution box in teh forward part of the engine compartment. Any reason they should be tied to a starter battery rather than the house battery?
 

bannister

Petty Officer 2nd Class
Joined
Oct 17, 2009
Messages
165
Re: 300SE Wiring Diagram

Cause that battery is supposed to be fully charged most of the time. It is the 1st one to be charged while engine is running and it only has to start the engine again.
If it was on a house battery, all other things (fridge, lights, water system, VHF, GPS, windlass etc) can consume the power and your bilge pump won't work when needed.
If the bilge pump has no power and something goes wrong............................................ have the pfd's handy.....
 

Taylor Made

Cadet
Joined
Mar 8, 2012
Messages
11
Re: 300SE Wiring Diagram

Is your boat out of the water when sitting for extended periods?

If so, you could disconnect the negative battery cable from the starboard battery when you are gone.

I also bet that your CO detectors are running that battery dry as well.
 
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