Ground somewhere....How do I find it?

[h2osk8er00]

So after a season of boating with my upgraded stereo system, I have come to find that I have a ground somewhere that is affecting not only the sound in the speakers when the boat is on, but also the instrument panel. Sometimes the boat is not willing to start..and other times it just clicks and acts like there is no power when I have two fully charged batteries. When I turn on the Bilge or the Blower, neither come on.... but the Fuel indicator shoots all the way down and the interior lights come on....WTF???? Not only do the interior lights come on but the front ones are way brighter than the rear interior lights.. The speedometer light is not on at all either. Seems like something is really messed up but I hope it is a quick fix, or an inexpensive one at that. Is this something I can tackle on my own and where do I need to start or look? Any help would be greatly appreciated!

[boatwakes]

Start with what you added that caused the problem in the first place. A bad ground will shut the engine off while it's running as well as not allow it to start or just click. Check the back of the keyswitch and make sure non of the bare wires or connectors are touching each other. Give some more info on what work was performed and by whom and when did this problem noticeably start.

[h2osk8er00]

Start with what you added that caused the problem in the first place. A bad ground will shut the engine off while it's running as well as not allow it to start or just click. Check the back of the keyswitch and make sure non of the bare wires or connectors are touching each other. Give some more info on what work was performed and by whom and when did this problem noticeably start.

Well I personally added the stereo last spring. Everything seemed to work just fine though... until later on in the season I started to hear the noise in the speakers when the boat was running. I also remember having problems with the boat not turning off when I turned the key off.. I would have to go to the back and turn off the boat by switching the batteries to off. So I'm sure it has to do with a ground somewhere. Makes me think it has to do with the ignition switch.. Anyway.. I added tower speakers and two amps to my system. Everything else pretty much remained the same. Let me know if you need more detail on the install but I wired it the way CHPtrill had me do it. So it should have been perfect because I know he knows what he's doing.. (Problem is I don't)...

[boatwakes]

The shutdown situation is most likely due to an internal keyswitch malfunction where it just isn't opening the circuit to terminate ignition. However, if you were unable to shut the boat off using the keyswitch, assuming the keyswitch is working correctly and also not loose in its socket, that means there is a battery positive loop in the ignition line AFTER the keyswitch. This wire is Red/Purp and runs from the keyswitch, through the wire harness connector on the engine and then to a wire junction where it splits off three ways: one red/pur wire goes to the starter slave solenoid where it gets power from the inline circuit breaker which is where the second line goes. The third wire runs to the alternator lead sensor. From looking at the wiring diagram from the mercruiser manual, if you were having trouble starting the motor, I believe you should start with the slave solenoid. But regarding shutdown or lack there of, shutting off the battery switch with the engine running most definitely caused the noise problem in the speakers. This is because the diodes in the alternator have now been comprimised and you're getting feedback through your audio system.
My recommendations are these: replace the keyswitch, replace the starter slave solenoid and rebuild the alternator, it'll just be the diodes that need replacing. It sounds like there was the proverbial cascade of bad boat luck that lead to where you are at now. In the future, for anyone else reading that can't shut off their engine with the key, open the engine hatch and pull the coil wire to the distributor cap being careful not to ground yourself out by touching any metal in the process. Keep me posted on what you find. Good luck.

[Dgreenhouses]

I have this same problem with my tower speakers Ringing. So having a bad ground can cause the speakers to buzz or ring? I thought I might have a bad RCA.