Electrical question.

[styler]

Not sure if this is the place to ask but I know you guys know these things.
This has been happening every since I've the boat (2 yrs) so not a new issue just one I've not addressed.
I notice that when I turn on the bow and stern lights (switch calls them nav and anchor)
The gauges read a little different. Especially the trim gauge.
This also happened even if I don't have the stern light plugged in. The trim gauge will read lower.
flip the switch off and all goes normal.
Amp draw issue maybe?

[lpugh]

Voltage drop issue, Will require a DVOM and voltage drop test to pinpoint where the problem is. Start with a battery test and verify the correct battery is being uses
950 CCA with at least 185 min. reserve, motor CABLE the first on and stack them largest to smallest, no wing nut, I prefer a flange nut or nylock.

[styler]

Voltage drop issue, Will require a DVOM and voltage drop test to pinpoint where the problem is. Start with a battery test and verify the correct battery is being uses
950 CCA with at least 185 min. reserve, motor CABLE the first on and stack them largest to smallest, no wing nut, I prefer a flange nut or nylock.

Napa 7234 commercial 1000cca 185 reserve capacity. Battery is connected as described with flange nuts. was always an issue before this battery too. Ill keep searching. omly changes when i flip that one switch .

[silverbullet02]

I’d make sure you have a clean ground run back for each. You can run that load off a garden tractor battery all day, got some bad connections or wires somewhere. Bad grounds can cause all kinds of randomness.

[styler]

I’d make sure you have a clean ground run back for each. You can run that load off a garden tractor battery all day, got some bad connections or wires somewhere. Bad grounds can cause all kinds of randomness.

I was thinking the load had to be minimum on those lights especially with only the front one on. When you say clean ground for each . you mean for the lights?

Ill start searching grounds .

[JOE54]

grnds can cause very unique problem for sure , sounds like voltage drop from short to grnd

[styler]

I've chased every wire a can and still no luck so far. Ive got it narrowed down to the nav light switch at the dash. Just to be clear this boat wiring is un butchered and looks as good as you'll ever see a boat of its age.
Dash switch up is navigation/anchor. down is anchor, and middle allows the anchor light to be turned on and off at the bow switch.
only time the current draw issue is when dash switch is toggled up (navigation) I tried unplugging all light fixtures and the up front switch. No change. everything else in boat works correctly.
Went through all the connections to the gages and their all tight.

[EuropeanAM]

I've chased every wire a can and still no luck so far. Ive got it narrowed down to the nav light switch at the dash. Just to be clear this boat wiring is un butchered and looks as good as you'll ever see a boat of its age.
Dash switch up is navigation/anchor. down is anchor, and middle allows the anchor light to be turned on and off at the bow switch.
only time the current draw issue is when dash switch is toggled up (navigation) I tried unplugging all light fixtures and the up front switch. No change. everything else in boat works correctly.
Went through all the connections to the gages and their all tight.

Wiring doesn't have to be "butchered" to have a high-resistance circuit or connection. See it all the time on brand new harnesses.

A good starting point would be to check resistance between the black wires at the gauges, and the negative battery terminal. With lights on, with lights off, key on, key off. Should be virtually NO resistance.

[styler]

Thanks Don Ill give that go tomorrow.

[styler]

I made up a ground wire and connected to the battery with an alligator on the other end. Tried connecting it to every gauge, switch , light ground connection or anything else I could find. Did all these one at a time. no change.
disconnected all the connection at the bow for the up front navigation light. no change. went through the fuse panel under the dash every wire there is good. I'm stumped.
Last resort I guess I can pull new wires to the front and rear nav lights and isolate them with a new switch but I'd rather find the issue.

[EuropeanAM]

Check the power supply (purple wire) circuit now. If you see no resistance there, you may have one or more gauges that are simply not working correctly (I do suspect it's resistance).

[billnorman1]

I made up a ground wire and connected to the battery with an alligator on the other end. Tried connecting it to every gauge, switch , light ground connection or anything else I could find. Did all these one at a time. no change.
disconnected all the connection at the bow for the up front navigation light. no change. went through the fuse panel under the dash every wire there is good. I'm stumped.
Last resort I guess I can pull new wires to the front and rear nav lights and isolate them with a new switch but I'd rather find the issue.

Connect your negative meter lead to that alligator clip, then check the ground wire at the dash. It should read 0 volts. It should stay at 0 volts when you turn on switches.

[styler]

Alright I haven't had time to do much but I at least tried what Bill said (didn't blow you off Don just haven't had the time yet) and connected my test lead to the negative on the battery ---to the negative on my meter and clipped the positive side of the meter to the main ground at the fuse panel.
Key on: nothing
Power switch on: .004 volts
power switch and nav light switch on .034 volts
So there is a small amount of voltage that to me should not be there.
A back feed I guess its called? Hopefully I can get back to this tomorrow but at least I'm finding something.
On that nav/anchor switch I'm seeing what I think is a diode . Wonder is it bad?

[billnorman1]

Doesn't sound excessive to me. That's voltage drop in reverse, but straight wire does always drop some.

[lpugh]

now do the same test on the power side. .0? is not an issue with circuit loaded. Would need to be more than .5 volts to be a problem
after testind the power side add the 2 together for total drop, prefer no more than one volt.

[styler]

now do the same test on the power side. .0? is not an issue with circuit loaded. Would need to be more than .5 volts to be a problem
after testind the power side add the 2 together for total drop, prefer no more than one volt.

Same on power side? Place the wire to the positive on the battery and main power to the fuse panel with the meter in between?

[lpugh]

Positive to positive. check the total circuit as well, meaning from battery to the loads, then narrow it down by battery circuit protection battery to switch, etc, this way you can find the exact spot that has high resistance.

[EuropeanAM]

You're essentially checking for high resistance by looking at LOADED voltage on both sides of the circuit (individually) and then adding the two together.

It also lets you identify if one side (negative, or positive) is considerably higher (immediately narrowing the search to circuitry on that side).

[Haughton]

This is some of the things I found when I re-wired my boat, similar issues with dimming lights and such. Not saying it is your issue, but connections and switches get tired or wiring will slowly brown(tarnish?) further up the wire if the connection is not good or insulation is damaged. Good luck sir

Bunch of grounds piggy-backed together


Also, a big offender was connections that had years of junk on them. Drimel with wire brush and a light touch cleaned them up

[DieselDood]

Try disconnecting the illumination circuit to the gauge.

I've seen gauges fail internally where they see the illumination circuit come on and the internal circuits have an issue causing the gauge to read wrong.