555e Alternator Wiring

[Nick350]

Hey everyone I am looking for advice on wiring a ford/new holland 555e alternator. The OEM setup is for a 3 wire alternator and that is what is currently on it. When I bought the backhoe the alternator was not charging so I was manually charging the battery and not shutting it off when I ran it for the past year. Now its time to give it some love so I began working on my list of issues.

The alternator that came on it was not for a backhoe and had a different mounting bracket that appeared to be off an old chevy pickup. I bought an OEM alternator and fabbed a new mounting bracket so its in and turns well. My issue is with the wiring, the previous owners ran only 2 wires, one to the battery via the starter solenoid power (on the stock wire) and a new line going to the fuse box (I don't know if this was supposed to work like a remote). This didn't work so I looked up the correct wiring in the service manual and installed the original wires coming from the main harness. This also did not work, I was getting .5 volt on both the power and warning lamp wires and nothing on the speed sensor wire. (I don't have a functioning warning light on the dash).

So I am now at the point of having to run new wires for the alternator and I am wondering what the bare minimum is that I have to do to make the alternator function? Any advice on this is greatly appreciated

 

[NH575E]

The speed sensor just operates the tach and is not needed for charging.

Disconnect the negative battery cable while you are making connections.

The B+ terminal (1/4" eyelet connector) needs a direct connection to the positive battery terminal. It is usually connected to the top post on the starter solenoid and should have battery voltage on it all the time. This needs a 10 gauge wire. The warning lamp should get power to one leg when the key is turned on and the other leg should connect at the alternator D+. A 16 gauge wire is sufficient for this. The current through the warning lamp excites the field when the key is turned on. Once that happens and the engine is started the alternator should begin charging.

 

[Nick350]

The speed sensor just operates the tach and is not needed for charging.

Disconnect the negative battery cable while you are making connections.

The B+ terminal (1/4" eyelet connector) needs a direct connection to the positive battery terminal. It is usually connected to the top post on the starter solenoid and should have battery voltage on it all the time. This needs a 10 gauge wire. The warning lamp should get power to one leg when the key is turned on and the other leg should connect at the alternator D+. A 16 gauge wire is sufficient for this. The current through the warning lamp excites the field when the key is turned on. Once that happens and the engine is started the alternator should begin charging.

thank you for the quick reply, for the D+ could I wire a switch in line between the battery and the alternator (onto the D*) in which I manually switch on when using? (acting as the key switch)

 

[NH575E]

I'm not sure. If you try that put a small like 10 amp fuse in the line just in case. Wouldn't you rather use the indicator so you know it begins to charge after you start it?

 

[Nick350]

I'm not sure. If you try that put a small like 10 amp fuse in the line just in case. Wouldn't you rather use the indicator so you know it begins to charge after you start it?

Unfortunately the spot for the light on the dash is completely missing, the only switch we have that functions is the 4wd so I don't know that I could wire it into the old and proper system.

I did a little more research given your information and I believe I can take a wire from the battery, put an inline fuse, then a switch, and then a light bulb (will look in manual to see size) and then connect it to the alternator. It seems the lightbulb provides resistance and you need that for it to function properly.

 

[Nick350]

Hey 575 just wanted to follow up with a thank you. Yesterday I installed the new wires and it charged like a dream.

I ended up putting a light bulb in line from the ignition to alternator and not messing with a switch. Functions great!

 

[edgephoto]

Actually the light bulb does not provide resistance. What it does it if the regulator is good it provides 12 volt potential to the exciter so the alternator will charge but if the regulator is no good there is a ground on that wire and the bulb lights up. Basic electrical voodoo. You could just put a straight wire there and get the same result. No real current flows through the filament of the bulb.