Hello,

All of my gauges spike when I use most of the switches (horn, lights, accessory, hatch, etc.), so I assume I have a faulty ground on the cicuit that's shared between my gauges and said switches.

I located the ground bus bar within the fuse panel, located in the cabin, just in front of the helm.
However, there's only 5 or 6 ground wires connected to that bus bar, and I have a lot more switches/gauges than there are wires on that BB, so I assume there's another bus bar that the remaining switches/gauges are connected to.

Anyone have any idea where the other grounding bus bars would be located? I pulled a speaker, the fuse panel, some gauges, the gear shifter, all to allow me to see inside the hull, to search for a bus bar or common ground wire, but to no avail.
I'm confident that if I work my way back from the correct bus bar, I'll find the culprit.

Thanks,

Blair

Hey Blair, it's pretty common to daisy chain all the grounds for a stack of gauges one ground to the next and so on and just end up with one lead to the buss, same on the grounds\ 12v to the switches. This is opposed to having a 12v and a ground coming off of every single switch and each gauge. So if you have ten gauges and ten switches looking for twenty grounds for example isn't going to help (I'm assuming). I'd imagine your best suited to look for a pigtail where all the wires from each come together and see what that attaches too; the bus probably, fuse box etc, look for a wire that's rubbed thru the jacket as well; lots of vibration in a boat. I'd bet the problem is somewhere there are a lot of wires grouped up.

Hi,
I actually worked at it yesterday. It tuned out that the switches were connected in series, as you thought it would be, but in groups of 3 or 4 switches. (Same for the gauges.)
it was quite challenging to follow the main ground wires from the switches and gauges, as they are routed and intertwined into larger bundles of wires, then into wire loom.
First, I verified that each gauge and switch had 12V, and they did. I then disconnected one ground wire from the BB within the fuse panel to see which switch/gauge would be affected. I repeated the process for all other ground connections, which allowed me to identify each switch and gauge to its respective ground terminal. Albeit, that still didn't solve my issue as everything had a 12V reading.

I then checked the voltage at each of the instruments that caused the other gauges to spike. For example, the navigation light switch, two accessory switches and the horn switch all caused my gauges to spike.
Voltage at the Port/Starboard light measured 10.3v, yet the voltage at the switch (on all output terminals) measured at 12v, with the switch in the on position. I could only assume that there was a power leak downstream, but where?
Note: I'm not sure if I mentioned this in my original post, but my horn doesn't work, it only makes a clicking sound. Seeing as the horn and navigational lights share the same ground wire, I assumed that the horn was only receiving 10.3v, which could explain why it's not working. (Not sure if the horn requires a full 12v to sound?) I couldn't measure the voltage at the horn as I didn't have anyone with me to depress the switch. (I could have bypassed the switch, but I didn't want to risk overheating the wires as it does draw up to 3 amps.) I removed the horn and connected it to an 18V battery that I have configured with leads for similar type testing, and it worked!
In hindsight, I should have connected it to a 12V battery, as I'm not sure if it was the additional 7.7v that made an inoperable horn work, or whether 10v just wasn't enough.

Seeing as I couldn't inspect much of the wires within hull, I decided to disconnect all the wire leads from each switch, one at a time, and then test my gauges for spike/flutter. I'm not sure which wire it was exactly, as I was on wire one thousand five hundred and eighty-three. Well, not literally, (lol) but it certainly felt that way in the blazing heat. Anyway, after reconnecting said wire, my gauges stopped spiking when depressing the switches. Only the horn still causes the gauges to react, but with much less severity than before. I think that's because the horn draws more amps than most other things, and because it's not working it's probably drawing more amperage?

Also, my voltmeter gauge has always registered between 10v and 11v throughout the entire RPM range, and it would drop to about 8v when being affected by depressing certain switches. With so many quirks going on, I wasn't sure if it was an alternator or voltage regulator issue. For the first time, it actually registers 12v to 13v. So, whatever wire I removed and inserted, it seems to have corrected a few issues. It's also possible that I shifted something when I was squeezing my arms into some tight areas in order to feel around for damaged wires. I'm not 100% sure what I did, but most of the issues are now gone. Just the horn remains to be replaced. Then I'll know for sure.

I'm not sure what's more frustrating, troubleshooting for hours at a time, or inadvertently fixing a problem and not truly knowing what you did?

Thanks for your input!

B

What your describing sounds to me like you've got bad connections on your switches, they could be corroded a little and making bad contact, when you remove and reconnect the connector rub a little corrosion of and contacts better.

If you disconnect your horn does everything else function properly? If your horn or any load (pump, light, etc) is bad it can be pulling more amperage than it should. Electronics do that in their way out, if you leave them to get worse they eventually can burn out or melt down or short completely. If your horn did example should require pull ten a psst is pulling 20 is telling you it needs to be replaced, if you test the system with the horn unplugged and all is well that's definitely the cause.

I tested everything with each appliance (inclusive of the horn) disconnected, one at at time. Problem was always present.

I know what you're saying about corrosion on the terminals, however, there's absolutely zero corrosion.
All the terminals and connectors are nice and clean. (They look new, but they are definitely not.) Also, prior to disconnecting any of the wires from the switches, I tested every terminal from the switch, and all had 12v. Point being, I hadn't manipulated anything yet, and I got a clean read on the first try. With that said, if I had to take a stab in the dark, there are these (not sure of the terminology) Y type connectors that slide over the switch terminals and allow two wires to connect to one terminal. (Like a splitter)
Well, the navigational light switch has several of those connected to it, and therefore, twice as many wires are connected to that switch (tension in multiple directions). With the wires connected, I couldn't see the underside of the switch, but I could feel that one of those Y connectors seemed to be spread further apart than the others, and I recall thinking that it might be pushing up against the middle row of terminals coming off the switch. (No visual, just by feel, so I can't be certain. ) But after disconnecting it from the switch, I squeezed the Y section closer together, just in case it was encroaching elsewhere.

That was the last switch I worked on when everything started working again.
I assume those Y connectors are common?