Testing wires

Starman8

Chief Petty Officer
Joined
Sep 17, 2010
Messages
630
Re: Testing wires

Not going to run a bunch of grounds. There are existing wires.

Wish I could send you the schematic I drew up.

I have ONE black wire at the panel, and it worked before as mentioned. It may be tied into the engine ground, a nono as you said, but I suppose it worked for 30 years.

That said, a black comes from the bow light along with the gray, the gray enters the harness, the black stays in the cabled sheathing and probably splices into the black leading into the panel from the harness.

The horn has 2 wires, red and black hanging freely, the red for the switch and the black to the BUS NEG

No wires from these 2 items go to the back of the boat.

At this point, the main black under sheath must run to the rear, and joins with the bilge/anc/tank grounds, and the guess is to the engine black somewhere under sheath.

I will PM you with my email. If you email me, I will send you what I think is going on.

I understand all that you are saying.
 

Starman8

Chief Petty Officer
Joined
Sep 17, 2010
Messages
630
Re: Testing wires

OK Silver, did more testing and visuals, and guess what, I misinformed.

I found the panel ground. It is back there in a faded periwinkel, the purple wire I was mentioning. The meter did its job. I also traced the pink sender, and also determined I have no switch(IGN) power at the helm for the fuel gauge. Instead of tapping into the control box, I am just going to add a switch and use the panel feed.

I also disconnected the harness at the fuel tank, and tested the ground there and the panel ground, and they are tied together which is correct.

This leaves one more issue, more of a question.

In this harness from the fuel tank, this is what it looks like:

The harness clip on the tank side has 2 male and one female connections. The pink sender and the sender ground are the males. The female is a blue wire that has a connector ring.

On the opposite clip are 2 females and one male. The 2 females accept the pink and black, and both have been traced and AOK. The male, which lines up with the blue female changes to a white wire with green stripe and appears at the battery. Testing for continuity concluded the following:

Putting the probe on the white wire with green stripe at the battery shows continuity with the blue wire on the opposite end of the harness. I think this blue wire is the tank filler ground(bond) as it has a ring connector and is unattached. I am starting to think that the white with green stripe goes to the NEG battery post and the blue somewhere to bond the filler cap/tank? The cap and tank are metal.

So the question is this. If I attach the white with green stripe to the NEG post, where do I attach the opposite end blue wire? They have continuity.
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: Testing wires

You said you had my fuel gauge diagram. It is correct so Pink and black do not go together. Pink is the sender wire. It should have a ring terminal and attaches to the threaded terminal on the fuel sender. The other end of that wire ends at the "S" terminal on the gauge. The metal shell of the sender assemblyAND the filler neck, AND the tank itself must be grounded to Battery Negative. How that gets accomplished doesn't matter as long as the connection is made. Ideally, this would be separate connections (three wires) connected to the battery (also known as a star connection). They could also be daisy chained (neck to tank, sender shell to tank, and tank to negative post with one wire). There is no reason to add a switch to simply operate a fuel gauge. If the engine is an outboard, and the ignition switch is bad replace it as it will need to be fixed anyway. With the key on, check voltage at the "A" (accessory) terminal. 12 volts = good. No volts = bad feed to the switch ("B" terminal) or bad switch. If this is an I/O, check for voltage into the switch. With key on, there shoule be 12 volts on the "I" (ignition) terminal. It is that terminal that feeds the gauges as well as the ignition circuit back to the engine.
 

Starman8

Chief Petty Officer
Joined
Sep 17, 2010
Messages
630
Re: Testing wires

There are NO wires from the control box to the panel. There are no wires from IGN to the panel.

All wires at the helm panel are present and accounted for. This boat originally had NO instrumentation except the pitot speedo which was lit from the bow light feed.

The PO changed from the plastic tanks to a permanent tank so there was never a need from original to have an IGN feed at the helm. The Merc O/B controls do provide a plug-in and I suppose I could get one for a 1979, but for $6 I can add a switch, hence the reasoning.

The PO stated he could never get the aftermarket fuel gauge to work, and I can see why. This gauge has only 3 connections plus the backlight bulb which has two prongs, one hot and one ground. The 3 gauge connections are S-I-G

I will put the pink on S, the black is incorporated in the panel ground from the rear, so I will jump a black from G to the Bus to complete that ground, and for power, will get a switch from EZ and feed the I from it. Oddly enough, I have seen boats use switches for multi-tank reads.

On the tip of the sending unit on the tank is a black jumper which goes to a post on the tank and secured, and tied to another black coming off and tests showed the tank and sender are grounded to the battery. The blue(maybe was green 30 years ago) shows a continuous read to the white with green stripe at the battery. I believe this was grounded via the NEG post of the battery, and the blue end(green) was once the filler bonding.

Upon further inspection, one of the locknuts below the filler cap was almost off, the other 2 very tight. I believe this was how the filler cap was bonded, and when the new tank went in, they disregarded it. I attached the blue(green) to that bolt, tested the cap for a 1.00 between it and the wire at the battery box. I believe I just grounded the metal fill system for anti-static.

So in a nutshell, there never was IGN power to the dash due to lack of instrumentation, no tach, no Voltmeter, nothing except a speedo pitot.

As I mentioned, the boat has started, the IGN works, the key works all thru the engine harness. After using this meter, I learned from it and your help, and it is appreciated.
 
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