Electrical issue- ignition switch?

[ufm82]

Hello All,
Had a recent issue with my boat that has me scrathing my head right now. Took the boat out and 5 minutes after being on the water I lost my tach, my volt gauge, fuel gauge and accessories like the radio and depth finder. Temp gauge pegged to the 250 degree mark. I saw the temp gauge shoot up and shut her down right away and then saw the other issues when I turned the key again. My radio and depth finder are both wired hot all the time through the buss under the console and so are not reliant upon the ignition switch. However, they were both inop now. If I touched any other switch like the horn switch, the bilge switch or other accessory switches, my engine alarm would give me the 3 beep signal like turning on the ignition. It did this until 30 seconds before we pulled the boat out and then everything returned to normal. (Of course.)
I initially thought I must have had a ground issue somewhere. After thoroughly checking all grounds at the console buss, the battery compartment buss and the cable to the battery I found nothing. I then pulled the dash out looking for a wire issue in the harness somewhere. All the while I am looking for a problem, the radio is playing and working normally as are all the gauges. I made some improvements while under the console as far as securing some harnesses that were barely loose and such. Everything seemed fine again so I buttoned her up and tried the key switch. The gauges responded normally and everything worked. For a minute.
Then, with no warning again I was back to the initial issue. Gauges funky, radio off, depth finder off, engine alarm sounding whenever any switch was touched. The only thing I did was turn the key switch. Can an ignition switch cause a ground issue that takes out these other items? The engine starts and runs properly despite these other issues.
1993 Merc by the way with the puch-to-choke key switch. I'm just running this past everyone to see if any similar issues have been experienced by any one else here. I plan to trace all wiring in the harness tonight but wondered if it's a switch issue. The switch is a 6 wire potted style switch that is original to the boat, a 1993 ProLine.
Thanks all,

UFM82

 

[boat1010]

Re: Electrical issue- ignition switch?

My son-in-law had a similar thing happen to him.. He would try to start his boat and everything would go dead.. Some times the radio and depth finder would work until he tried to start the boat. He said he checked every thing at the lake and couldn't find any thing. I asked if he checked the battery connections? He said he did.. I'm a little hard headed so I went to check the connections and took them all apart and cleaned them really good. Put everything back together and has been working fine ever since. And that was two months ago. Not saying that is you problem but just make sure you check that. Other than that I think it is a loose connection somewhere to the bus, and can be either side. Positive or neg. Best of luck...

 

[Home Cookin']

Re: Electrical issue- ignition switch?

not that this will solve your problem, but as an example of what you are up against, I had a mystery intermittant electrical problem; my fuse that covered the PTT, Fuel guage and starter would blow; it seemed after lots of observation to occur when the RPM's reached a certain point. After replacing almost everything from key to engine block, some things twice, we found that the steering was a little loose and would touch the powered nut on the back of the fuel guage. A simple fix that took $$$ and over a year to find.

On another motor (20 hp), it would die as you accelerated. Had to be fuel related, right? No. the stators, etc. under the flywheel shifted slightly when you went from idle to run. That movement causes a frayed wire to ground against the block, shutting it down on acceleration.

One technique for finding these shorts is to run in the dark and look for sparks. Obviuously not for every situation.

Good luck!

 

[ufm82]

Re: Electrical issue- ignition switch?

Oops- sorry. Wrong place.

 

[Silvertip]

Re: Electrical issue- ignition switch?

Point of clarification here. Tke notice EVERYONE that loses an "electronic device" - not an electrical accessory like a horn" when you turn the key to START. The "A" terminal on the ignition switch for an output is what powers instruments but some folks tend to wire radios and other "electronic" stuff to that terminal. What happens is if you have that stuff running when you turn the key to START, the connection between the "B" (battery POS) and the "A" terminal is lost. Most ELECTRONIC stuff will shut off when power is lost and will not turn on again until you hit the POWER button. ELECTRICAL items like lights come back on when the key goes back to RUN because no ELECTRONICS are involved. Try this test. 1) turn the key to RUN and turn on accessories. Watch gauges, your radio, etc and then turn the key to START. Note that they turn off for the reason I mentioned. Lights will come back on when the key is released because power is restored. ELECTRONICS need to be turned on again. Perfectly normal operation. While this test is for an OUTBOARD, the same principle applies to an I/O with the B (battery) and "I" (ignition) terminals.