Mando alt wire question

Not sure what would happen. You said you're charging.

Wonder if not having the jumper puts it in full field output all the time.

Paul, in your pic, is that original alternator, wired the original way? Any idea what your voltage reads at the battery with the engine running?

Yea, it's a little confusing. Our manufacturer used to supply those with the flat jumper but have since stopped. We were installing them and they weren't charging the system then we figured it out.

Brian, on the right rear of the alternator the S terminal needs to be somehow connected to the large positive terminal (not to the green wire or EXC terminal. That terminal is reserved for the keyed ignition source to energize the voltage regulator. The S terminal senses actual alternator/system voltage.

This jumper doesn't show up on the diagram because it is already jumped on the stock Mando alternators.

Look at your first picture, there is a flat "wire" covered in black insulation that runs between the B and S terminals.

Gotta watch some of those too. They don't have that solid jumper from the large positive to the S signal terminal so a jumper is needed there.

We get ours from a local warehouse (that is USCGA) but much cheaper than pcm but they require the additional jumper wire.

Here's a pic of my '95 GT-40 wiring

Yeah the the one that is circled purple is actually a green wire that runs back to a purple wire. The gound has a purple stripe on it and that is what confused me.

What is the sensor jumper wire? A lot of diagrams show a jumper from the sense to hot? Pretty sure my old one didn't have one.

I just hooked it all back up and have 100% power to electronics. Hope to make a lake test tonight.

OEM style replacement. I am going to go back and make sure I bolted everything down today. Hopefully get a lake test as I havent had a lot of time.

sorry due to my other engine post i didnt think about posting that info here.

1995 supersport pro boss gt 40

Solenoid (starter relay?) needs a ground, I've had problems with replacements not getting a good ground through the case so I built a short 2ga jumper that I connect between a bolt and the head.

The jumper with the sense wire is not ideal, but will work.

Ok so after a lot of searching I came across a good read that lead me into the right direction. Now my question is do I have to have the jumper wire? I am 99.999% sure my old one did not. Could it have been internal?

So now I have power back to everything but when I turn the key I get nothing. The ignition button powers all the gauges and the volts look right. It may be Thursday before I can spend more time in boat. Could that missing jumper wire cause me to get nothing when i turn the key? Could I have fried the coil or something with the alt ground hooked to exciter?

The heavy Orange wire connects to the "B" terminal which is the alternator's output terminal.
The Green wire needs a ring terminal and connects to the "EXC" terminal which is the Field Excitation terminal (goes to +12V when the ignition is ON). This is despite the color coding you may have seen in some Mando diagrams like the one attached to this post. The green wire eventually connects to the Purple ignition wire, somewhere back in the harness or terminal block.
The Black wire is a redundant/backup connection to the engine block (ground) and should be connected to the "E" (for "Earth") terminal, which is the alternator's frame.
There should be a jumper link between the "B" terminal and the "S" terminal which is the voltage sense terminal for the alternator's internal regulator (see the photo in the previous post). If that jumper is not there, you need to make one. I'd use a #12 AWG wire.
The "P" terminal is an AC output to a tachometer (would be used on a Diesel installation - unless it has a tach sender on the crank). Leave this terminal unconnected.
The "L2" terminal is for connection to an "Idiot Light" on the instrument cluster. It would light up if the alternator were not charging, like on a car. This terminal is left unconnected since the boat has an ammeter. I am not sure if it is functional on the Mando alternator but it may be.

Since you've now had the 1000 words, here are a couple of pictures also:

1 - The terminal pin-out for a Mando (ignore the Black or Purple wire reference to the "EXC" terminal).

2 - A wiring diagram for a PCM engine showing the three wires connected to the alternator. The Black ground wire is shown in a confusing position on the alternator, in the sketch, but does indicate it connects to the engine block.
http://www.fishtheclassic.net/forums/archive/index.php/t-17942.html