Bad Switch or Something Deeper?

[Injury]

Got the engine on my boat running (89 Stratos Fish & Ski), and low and behold nothing in the dash works, court and nav lights don't work, gauges don't work, it looks like the trim gauge may be getting energized but it's never really worked. Only thing electrical that functions is the power trim, electric start, and the warning buzzer (trolling motor works too but that's on it's own battery).

In tracing down my loss of power I came to the main Power Switch in the dash. What's confusing me is if I pull the connectors off of the "load" side I get power on that side of the switch, as soon as I reconnect it that blade loses power. Doing a quick short across it lights and stuff illuminates (didn't want to short it too long and risk burning something else up so not much testing done that way).

So my question is have I found the likely culprit in a bad switch, or is it probably something further down that's causing this symptom. It kind of confuses me as I figured a mechanical toggle switch is one of those "it works or it don't" kind of parts and wouldn't be influnced by the load on it.

 

[belairbrian]

Re: Bad Switch or Something Deeper?

From your description there are a couple of things that come to mind.

The switch may be corroded inside. If it is bad enough it might show voltage on a meter but not be able to pass enough current to support any load.

As for the voltage being there with the load wire disconnected:

I take it you had the black lead on ground and the red lead on the output terminal of the switch when you saw 12v.

When you reconnect the wire and probe the same points there is probably very little potential difference between the leads. All it would take would be one instrument with a low resistance value to make the meter read 0.

If the power switch is fused jumpering the wires has no more risk than flipping the switch. If there is a problem down line the fuse will blow.

If the power switch is not fused:

To be safe you can remove both leads from the switch, jumper them with a fuse. Just use s plastic in-line fuse holder and add the necessary connectors. Probably male terminals. Turn every thing off add the jumper and test each circuit with an appropriate size fuse. Can't really say what size fuse that is without knowing the boat better.

The boat I recently bought has different things wired different ways. Some are on the master power switch, some on the ignition and some go through both. I'll be cleaning that up this winter. I plan to have the engine on the ignition switch and all gauges, and lights on the master power. The bilge will be on a separate fused circuit. The previous owner wired the float switch directly to the battery so he didn't have to remember to turn it on. Despite burning up 2 bilge pumps when the float hung open while trailering he never changed it.

 

[Injury]

Re: Bad Switch or Something Deeper?

thanks for the advice. This one is going to get a rewire now that I'm into it. Looks like someone started and left half the old wires laying back by the batteries. So I'm tracing things like wires to 6 wire OEM connectors with only one wire hooked up the rest laying unhooked. Just an ugly birds nest.

Due to the location, controing my body, and the shortness of the wires only letting me pull the dash out a couple of inches I wasn't able to get my voltmeter in a handy spot to test (doesn't have aligator clips). So I was having to rely on one of the 12V LED circuit testers.