1g Alternator

Dave99gst · Post by **Dave99gst** » Sun Feb 08, 2009 8:24 am

What do i need to make a 1g alternator work in my sandrail project?
I have a plug i can cut out of a harness. I know i need the large wire that goes from the post to the battery but what other wires?

Any thoughts ?

thanks all ~!

Djchunter · Post by **Djchunter** » Sun Feb 08, 2009 2:12 pm

its a ground and a 12v key hot for the voltage regulator. Just make sure you hook the wires up right or you will fry your alt.
Dave
Coldwater Motorsports

Dave99gst · Post by **Dave99gst** » Mon Feb 09, 2009 8:05 am

Thank you sir ! Any idea as to what one is ground and what one is Hot ?

hschwartz3 · Post by **hschwartz3** » Mon Feb 09, 2009 2:54 pm

Not sure if this is what your asking for, but I’ll share what I know. I’ve cut and pasted some pages from the 1G factory service manual to assist you. But most all internally regulated alternators produced after the late 80’s are wired nearly the same and the 1G is no different.

There are three connectors on the back of the alternator the B, S, and L terminals. The “B” terminal is the large stud that is used to connect to the battery. The “S” terminal is the “sense” lead that senses load on the alternator. The “L” terminal is the idiot “light” lead terminal. This wire is also responsible for “exciting” the alternator. The alternator ground is the casing.

Run 1 wire (14 gauge is usually fine) from a switched power source (ignition switch) through a dash mounted light to the “L” terminal on the back of the alternator. Next run a short jumper wire (12 gauge should be fine) from the “S” terminal to the “B” terminal. Then run a large wire from the “B” terminal to the positive battery terminal. Size of wire and fuse here is usually determined by the size of alternator and the load. Note in service manual pages the circuit is protected by a fusible link and circuit breaker. And likewise some fuse, breaker, or fusible link should be used.

I’ve used this same method on many vehicles and have never had a problem. For instance: Derby cars, converting a six volt tractors to 12 volts, or when converting an older external voltage regulator / generator vehicle to an internally regulated alternator vehicle. Wiring up this way, the dash light will light when alternator is not producing any output or the ignition is on but the alternator is not turning (motor stopped).

Hope this helps.

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Dave99gst · Post by **Dave99gst** » Mon Feb 09, 2009 9:31 pm

Thank you ! That deifnly help me understand whats involved a ton.

2 questions... Do you see any reason that i cant omit the dash light? ( no need for it on a sand rail )

and.. how do i determin what wire is "L" and what one is "S" on the alternator??

hschwartz3 · Post by **hschwartz3** » Mon Feb 09, 2009 10:20 pm

Sure, you don't have to use a dash light. It will work with or without.

I can't say 100% sure which terminal is which. My alternator too is missing the stock female B19 connector, and I haven't wired mine up yet. But looking at the service manual, the "L" terminal should be the right side of the connector if you were looking at the back and would have been a black wire with a white stripe. The "S" terminal should be the left side and would have been a yellow wire.

Can anybody confirm this?

hschwartz3 · Post by **hschwartz3** » Tue Feb 10, 2009 8:51 am

Furthermore, it would'nt hurt if you reversed the "S" and "L" leads. Your applying 12v to both of them, but the "L" terminal needs to be switched. This is cause it would drain your battery overnight if it was'nt. Just don't ground either of those wires. There's only two possible combinations, one will work, the other way will drain your battery. A simple digital volt meter test on the battery before, during, and after will confirm the right way.

If you were still suspect, take the alternator to the auto parts store and ask them to test it. Then note or ask which leads are which. Then you'll know if your starting out with a good alternator too.

Dave99gst · Post by **Dave99gst** » Wed Feb 11, 2009 11:54 am

I just took a look at the harness i got. One wire i got is in fact black with a white stripe, the other is solid white and a heavyer gauge then the black&white one.