Alternator exciter wire sending 12v to coil.

[Rando1201]

Hello, I bought this engine used. Im not sure how to identify the posts on the alternator. It is a vdrive so it is difficult to get to. The problem i am having is the exciter wire is hot with 12v with the ignition switch turned off and battery on. Previously I had to figure out why my fwc electric pump was turning on. After removing the exciter wire from coil + the problem was solved. Later i tested with a voltmeter and found 12v at the wire. I have tried to find my alternator online but it is painted over. I have attached pictures for reference. Im trying to find the output. I am running an ammeter not voltmeter. Just what came stock on my columbia 30 gauge cluster.

[ndutton]

Yours is the early Motorola style, upper right picture

[Rando1201]

You are the man! Thankyou!

[Rando1201]

So from what im seeing there is no exciter wire. Hmm that is the wire I had going to coil positive. Which was the problem.

[ndutton]

In the picture, Ignition + is the exciter.

[Rando1201]

I see, but what im saying is when the ignition switch is off i am still measuring 12v from the exciter wire even when it is not on coil positive.

[joe_db]

Either you have the wrong wire or something is wrong with the alternator.

[ndutton]

Were you having any problem turning the engine off? With 12V coming from the exciter wire and with it connected to coil + I would expect the engine to continue running with the key off. Something is not adding up.

[Surcouf]

Were you having any problem turning the engine off? With 12V coming from the exciter wire and with it connected to coil + I would expect the engine to continue running with the key off. Something is not adding up.

unless the fuel safety shut off valve is wired on a seperate circuit that losses 12V when the key is turned to off... (which it should not ...)

[ndutton]

unless the fuel safety shut off valve is wired on a seperate circuit that losses 12V when the key is turned to off...

Even so the engine would continue to run for a minute or more.

[JOHN COOKSON]

the exciter wire is hot with 12v with the ignition switch turned off and battery on. Previously I had to figure out why my fwc electric pump was turning on. After removing the exciter wire from coil + the problem was solved. .

Who knows how the previous owner has the boat\engine wired? The exciter wire should should be conducting electricity from coil + to the alternator not the other way around. I'd rewire the engine the way it was originally with the exciter wire to coil + and go from there.

ex TRUE GRIT

[Rando1201]

Were you having any problem turning the engine off? With 12V coming from the exciter wire and with it connected to coil + I would expect the engine to continue running with the key off. Something is not adding up.

No I am able to kill the engine with the ignition switch.

[Rando1201]

Who knows how the previous owner has the boat\engine wired? The exciter wire should should be conducting electricity from coil + to the alternator not the other way around. I'd rewire the engine the way it was originally with the exciter wire to coil + and go from there.

ex TRUE GRIT

Ok, I am down to a relay, which I think might be the problem. Not totally sure though. The main issue is that the electronic water pump doesn't shut off when I flip the ignition switch. Yet my gauges do shut off, and that's everything on coil positive.

I think since I had gone to the channel islands, where I had a hot coil issue, it may have burned up something in the relay for the electric water pump.

Thomas from Indigo is sending a new relay assembly for shipping costs only, as he is helping me diagnose this issue over the phone.

I did wind up taking the wire off of the alleged alternator output, and ran the engine while testing voltage with my multimeter, and did get a strong voltage there. So I know my wiring is right. The ammeter does move with RPM, so I believe I am right there.

I would think if the exciter wire is back feeding the electricity, then my guages would still be powered. Not sure of the issue, if anything I will just wire another switch for the water pump.

As of right now when I turn the ignition switch on, everything powers on as it should, but when I flip the ignition switch off, the only thing that doesn't shut off is the water pump. In order for me to turn the water pump off I have to toggle the battery switch to on/off, then flip the ignition, and it turns on.

Ill update on Friday when I get the new relay.

[Rando1201]

Update.
The relay was not the issue.

I removed the exciter wire and the water pump shuts off with the ignition.

I tested voltage on the output to the ammeter. I maxed at rpms and read 17volts at the highest and around 13 just after idle. My boat didn't come with a tach.

There is no noticeable difference from starting to not starting with the exciter wire detached.

I also sanded the name plate and found Mr12n451d type b.

I did just test the exciter wire its the only one with a square connector and a coil in the wire, the voltage increased in this wire as well.

[ndutton]

I removed the exciter wire and the water pump shuts off with the ignition. . . . . .I tested voltage on the output to the ammeter. I maxed at rpms and read 17volts at the highest and around 13 just after idle.

17 volts is obscenely high and tells me you have no functioning alternator regulation. If you continue to run this way it's going to damage something. Maybe it already has, particularly your Channel Islands overheated coil. Have you replaced that coil? You should.

I did just test the exciter wire its the only one with a square connector and a coil in the wire, the voltage increased in this wire as well.

Strike two on alternator regulation. Based on what I'm reading in this thread I recommend replacing the alternator outright.