Electrical weirdness

M

mhanch

Member
Joined
Oct 9, 2007
RO Number
28764
Messages
19
ok folks, I have a really odd issue in my dash. I have a 3396 Mariner 1977, and when I turn the switch on to turn on the lights in the dash and Gauges, all the gauges for my port engine go haywire. they peg out at their max settings. Starboard gauges work fine.

Any ideas?
 
It's been this way since I got the boat (september) I'll check the grounds again.
 
I agree. I always use the rule of thumb that if it appears you have to hire an exorsist to purge the demons in your boat's electrical system (or an automobile for that matter), then its usually a ground.

When a ground goes bad - whether it be corrosion in connectors or some other area, then the return path is not certain. Electricity is kind of goofy in that regard, and will eventually find a path to ground - sometimes through other equipment. When it does, its pretty unpredictable what it will affect.
 
Those boats have a panel on the underside of the dash to which all the spade connectors are plugged to connect all the grounds. I'd check that (there may be 2 of them). Also, I'd look at the back of that light switch and just make sure no wires are shorting out on it, or rubbing against the tachometer leads or whatever other gauge is nearby. Those old dashboards were often a mess of wires all connected to one overloaded lead someplace, especially if the prior owner did a lot of amateur wiring. Maybe when you energize the switch its sending power to the wrong place via a short...
 
maybe disconnect the wiring one guage at a time. Start with the ground from that guage and then the hot lead to the lightbulb in that guage. I would still poke around first as others suggested looking for loose, corroded or a wire touching something it shouldn't. Just for kicks I might bring a good ground from somewhere else and see if things work better.
Eddie
 
To make it simple, just run a new ground. You will know right away if that's the problem.
 
IMHO its not that simple. Older Carvers had wiring harnesses that resembled your grandmother's favorit spaghetti dishes. Its going to take some work to check this out. The only thing in his favor is the fact that they have those blocks of spade connectors screwed to the underside of the dash, to which all the grounds supposedly go. But not always. And not if the previous owner was an "amateur electrician"...
 
Yeah, I have several added bits from the previous owner. I may just start removing some of the crap and see if that helps.

Does anyone know, are the engines grounded together? does it matter where I run a ground from?
 
USCG reg:

33CFR183.415 Grounding:

If a boat has more than one gasoline engine, grounded cranking motor circuits must be connected to each other by a common conductor circuit that can carry the starting current of each of the grounded cranking motor circuits.

ELEC-F11.gif
 
Fixed!

The dashboard grounding cable was broken off at the engine block. It took all Saturday to trace the wires under the dash, and a bit of testing with the voltmeter to figure that one out.

Once I knew the ground cable was dead I just had to look for the broken connector. Once I replaced the conector, the dash works fine.

Now I need to go back in there and replace all the burned out lightbulbs. :)

Thanks for all your help!
 
Glad to hear it worked out!!!

BTW here's a tidbit I ran into awhile ago - for all of you who might still use point fired ignitions...

My boat had an engine synchronizer at one time, but we had disconnected it (or thought we did!). Later on I had a situation where one engine's condenser would prematurely burn out, and then when I changed it, the OTHER engine started having condenser problems! The reason was traced to the synchronization circuit (across the tachs) - the original engine's condenser actually had been good - it was the OTHER side which was in bad shape but it was drawing from the good one through the now-defunct synchronizer circuit!!!

In other words, engine #2 was going to fail all along, but it was sucking from engine #1, so my replacing engine #1's condenser didn't do a damn thing except waste my money. Big deal, $5.00 - but it was the lesson in electrical circuitry that was worth noting...
 
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