3 wire gm alternator

ford 2600 in maine · Mar 23, 2023

Does someone have a wiring diagram of a GM 3 wire alternator.
Key switch has battery, acc., ign.,s post in center

ford 2600 in maine · Mar 23, 2023

I do not have an ammeter of volt meter on tractor. Tractor is a ford 3600.

Janicholson · Mar 23, 2023

Simple: The #1 side spade terminal goes to the ACC terminal of the Key.
The #2 spade goes directly to the output terminal (6 inch wire with a ring terminal to fit the output stud)
Both of these are 12 gauge wires.
The output connects to the Amp meter load side through a 35 amp fuse (auto store) The fuse prevents letting the smoke out of things!!
That is all that is needed. The output wire should be 10 gauge.
The load side of the amp meter is the one not connected to the battery!
If the lights are 6v they need changed to 12v (LED is best)
If it was 6v positive ground the amp meter needs to be connected with all wires on opposite sides so it reads correctly.
The coil should be fitted with a ballast resistor (mid 60s Chevy) if not changed to a 12v no resistor required coil.
No diode or other resistor or light is needed!
Jim

Butch(OH) · Mar 23, 2023

If a light or diode is needed or not for the #1 wire depends on the complexity of the ignition switch. #1 must be switched on and off with the engine and it cannot be common. with the ignition power otheriwse the alternator will power the ignition with the key off and the engine will not shut off. Not familiar with that model of Ford but most tractor installations will require either an idiot light or a diode in the #1 wire

Butch(OH) · Mar 23, 2023

Diagram for 10SI.

JMOR · Mar 23, 2023

No ammeter, no voltmeter and 2600 Alt Warning light is different from 10SI and if he wants to use it, he must change BOTH connections to the lamp. He doesn't need the current alt output diode either.

Butch(OH) · Mar 23, 2023

Right, either a light or diode is required
but not both

JMOR · Mar 23, 2023

(quoted from post at 16:54:45 03/23/23) Right, either a light or diode is required
but not both

cc switch position may mean that he needs neither light or diode or resistor.

Geo-TH,In · Mar 23, 2023

I ran the #2 connection wire through the acc switch after I measured a parasitic drain.
Bench test alternator for a parasitic drain.

Butch(OH) · Mar 23, 2023

The #2 wire is voltage sense and I have heard of people having the same problem but I have never experienced it. I believe that there is some internal issue with the alternator when it draws a current through the #2 wire when not running. For the #1 wire that would be normal as it is used to excite the field.

Janicholson · Mar 23, 2023

He indicates an ACC terminal on his switch. in effect that is an isolated off not connected to the ignition circuit. Using that to excite is fine and dandy. if desired, that circuit could have a dash lamp installed in series with the wier to ACC and it would act the same as a road vehicle warning lamp. Jim

ford 2600 in maine · Mar 24, 2023

Please post diagram

I have diode

Butch(OH) · Mar 24, 2023

Check you switch terminals with a meter. If the ACC Terminal is powered with the key to ON and not powered when the key is OFF yet separated from the IGN terminal when the switch is off (check between them with an ohmmeter) Only then do you not need a diode or light. Problem is I have never seen a tractor switch that works that way, of yours does I stand corrected. The ACC terminal is usually powered when the key is turned backwards from off and that won't work. The diode would go where the light is shown in the drawing I posted.

Geo-TH,In · Mar 24, 2023

Why take a chance of the alternator draining the battery?
The alternator on a 20 hp honda drains the battery.

Rich'sToys · Mar 24, 2023

Also, the diode can only go in one way. There is a white stripe or band on one end. That end is closest to the alternator. If you get it backwards, it won't work.

JMOR · Mar 24, 2023

(quoted from post at 01:59:23 03/24/23) Please post diagram

I have diode

This post was edited by JMOR on 03/24/2023 at 11:54 am.

Jim.ME · Mar 24, 2023

(quoted from post at 07:49:26 03/24/23) Check you switch terminals with a meter. If the ACC Terminal is powered with the key to ON and not powered when the key is OFF yet separated from the IGN terminal when the switch is off (check between them with an ohmmeter) Only then do you not need a diode or light. Problem is I have never seen a tractor switch that works that way, of yours does I stand corrected. The ACC terminal is usually powered when the key is turned backwards from off and that won't work. The diode would go where the light is shown in the drawing I posted.

Any ignition switch I have encountered that has an ACC position powers the ACC when the key is turned right to the run position where the ignition is powered. Turning the key to the left turns on only the ACC connected items, not the ignition. They are separate as the propose is to let a radio, for example, be on without having power going to the ignition circuit which could damage points or electronic units if the engine is not running.

Janicholson · Mar 24, 2023

Just hook the alt output through the fuse I specified tp the starter relay (solenoid) on the terminal that connects to the battery. Jim

Janicholson · Mar 24, 2023

The accessories terminal works with two internal contacts. one only gets power when the key is on ACC. The other gets power only when the key is in RUN. (this makes sure the accessories work when operating the vehicle/tractor) in the off position, there is no internal connection between ACC and IGN. Jim

JMOR · Mar 24, 2023

(quoted from post at 12:18:26 03/24/23) The accessories terminal works with two internal contacts. one only gets power when the key is on ACC. The other gets power only when the key is in RUN. (this makes sure the accessories work when operating the vehicle/tractor) in the off position, there is no internal connection between ACC and IGN. Jim

o, on this 2600 he can only have instruments when in ACCESSORY position, but not whole running down the road? Not likely. see schematic diagram.

This post was edited by JMOR on 03/24/2023 at 11:55 am.

3 wire gm alternator

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