GM one wire alternator

[fjseymour]

1968 Dauntless V6 CJ5. I'm installing the "One Wire" alternator. The installation looks basic, but I have a stupid question. What do I do with all the extra wires? I do have aftermarket Temp, Oil, & battery gages.

 

[colojeepguy]

I removed the voltage regulator and the wiring between it and the alternator. The gauges should not matter unless they're pulling 12v directly off the alternator.

 

[Oldpappy]

The "one wire" alternator with internal regulator greatly simplifies the wiring, but it is important that the charge wire coming from the alternator is sufficient gage for the output of the unit. If the alternator is a high AMP output the stock wiring is probably not sufficient, and will cause a voltage drop, or if too light of gage could cause an electrical melt down.

For example, I just installed a Power Master one wire 100 amp alternator on my 48 which also has the Dauntless V6, but that really doesn't matter. I eliminated the voltage regulator and wiring and the 10 gage wires going to and from an ammeter which I replaced with a Voltage gage. The charge wire for an internally regulated one wire alternator can run directly to the battery, or to the battery post on the started solenoid. I ran a 6 gage charge wire from alternator directly to the positive battery terminal, probably overkill, but what I had on hand. I now have 14 volts charging at idle, and battery stays fully charged, when in the past it would barely turn the engine over after a long trail ride at low RPM.

 

[fjseymour]

Thanks guys.

 

[Jw60]

I used copper jumper cables from alternator to battery. Positive and negative are connected at the alternator.


Mine is technically a standard alternator with a jumper to itself and an idiot light. The jumpered sense wire will only work with a heavy guage wire of minimal resistance.

I've melted a lot of the old wiring. I think it's had 5 electrical fires. Dash twice, seat once, rear turn signals, and the power to the horn.

 

[jeepdaddy2000]

I know you already have the 1 wire, but I prefer the 3 wire set up. It retains the idiot light which is a visual indicator of the charging system.
Most aftermarket 1 wire alternators can be converted, so this may still be an option.

 

[linckeil]

I'm not knocking one wire systems, but there are a lot of reasons to stick with a three wire system. When i was debating these options, this article helped me make my decision:

http://www.madelectrical.com/electricaltech/onewire-threewire.shtml

 

[Fireball]

I know you already have the 1 wire, but I prefer the 3 wire set up. It retains the idiot light which is a visual indicator of the charging system.
Most aftermarket 1 wire alternators can be converted, so this may still be an option.
View attachment 107704

Powermaster 1-wire alternators have the post for the charging light on the dash. It has no effect on the charging, but it's nice to have the working idiot light. It also has the advantage that a burned out idiot light will not stop the alternator from charging.

I have one of these in my DJ-3A with the light wired up.

 

[Fresbone]

I used a Painless Performance harness and a 3 wire alternator in my CJ, but I have referred to the installation manual for wire gauge and other questions on my JC. This manual should have information about how to wire different types of alternators and the wire gauge they recommend.

https://painlessperformance.com/wp-content/uploads/2024/07/90501-Manual.pdf

 

[Oldpappy]

My 48 doesn't have an Idiot light. I installed a voltage meter instead.

 

[Fireball]

My 48 doesn't have an Idiot light. I installed a voltage meter instead.

I have both in the DJ. I like having the light because I may not be paying attention to the gauge.

 

[Ol Fogie]

I have both in the DJ. I like having the light because I may not be paying attention to the gauge.

X2, I am watching traffic most of the time. I even have a ''key in ignition'' buzzer from an older model ford car wired to an oil pressure light sending switch on my diesel truck. Buzzer comes on at key on and shuts off the instant oil pressure comes up. Lost a diesel engine once when a sudden oil leak cost me an engine when I didn't catch it in time, 45 seconds pulling at full throttle and max torque without oil pressure will destroy a truck engine.

 

[Ol Fogie]

I'm not knocking one wire systems, but there are a lot of reasons to stick with a three wire system. When i was debating these options, this article helped me make my decision:

http://www.madelectrical.com/electricaltech/onewire-threewire.shtml

x2, on the MAD electrical article.

 

[Tralehead]

I know you already have the 1 wire, but I prefer the 3 wire set up. It retains the idiot light which is a visual indicator of the charging system.
Most aftermarket 1 wire alternators can be converted, so this may still be an option.

Same set up I have, only I would reco 8awg for the charge wire, and the little plug for the flat contacts is available just about anywhere, sold as a "Delco" part. I have mine wired to the idiot light in my big round stock speedo.

 

[timgr]

IMO the main reason to go with the 3-wire OEM alternators rather than some aftermarket unit is price.
In Jeep applications, the 2nd wire, the sense wire, is immediatly tied back to the charge wire, as seen in the diagram from JeepDaddy2000 above.
This turns the 3-wire into a 2-wire alternator.
The third wire is the exciter, which in OEM applications gives the initial current needed to start the alternator charging.
The aftermarket 1-wire alternators have a regulator with a circuit that supplies this initial 'bootstrap' current.
The alternator uses part of its output current to create the magnetic field that generates more output current.
It has to start with something to generate more.
The exciter wire also provides an indicator light on the OEM applications.
Seems like the aftermarket suppliers add this feature back in (with reduced function) to address what some see as a deficiency in the aftermarket alternators.

Also, the Mad Electrical article gives you a list of clocking choices based on their list of applications.
Clocking SI alternators is super-easy using a special tool like a toothpick or paper clip.
Take the halves apart, hold the brushes back with your special tool, and assemble with the clocking you want.
There is a hole in the case for this purpose.

 

[colojeepguy]

I have a 1 wire alternator on my Jeep, it's been on there so long I don't even remember where I bought it from. It's worked great for me!

 

[jeepdaddy2000]

In Jeep applications, the 2nd wire, the sense wire, is immediatly tied back to the charge wire, as seen in the diagram from JeepDaddy2000 above.
This turns the 3-wire into a 2-wire alternator.

Looping the sensing wire directly back to the charging cable is actually a technique for adapting a 10SI to many vehicles. While not "perfectly" accurate, it gives the alternator an idea of what is going on.
In later Jeep applications, where the 10SI is stock (as well as most GM applications), the sensing wire is buried in the loom itself. This is to "better" sense the voltage throughout the loom.

 

[timgr]

In 1975, Jeep adopted the 10SI for six cylinder Jeeps, and used the ref'd wiring scheme.



The V8 Jeeps did not get the 10SI until 1978, using the venerable Motorola components in 1975 and a Motorcraft alternator/regulator in 1976 and 1977. From 1978 on, all Jeeps got the 10SI through the AMC years, AFAIK.

 

[Tralehead]

I clocked a 10si and never used a toothpick! The horror...