general motors 3 wire alternator wiring diagram

Hooking the Sense wire to the battery positive on the alternator will make the regulator prematurely limit the voltage output. It needs to sense the current draw on the battery, not the output of the alternator. If you only have an incandescent bulb and it burns out then there will be no current flow!Ĭ: I/F- 12v ignition used when there is no alternator warning lamp in the vehicle or as a redundant method of exciting the alternatorĭ: S- Battery Positive Voltage can be a fused (5 Amp) link the positive battery terminal, to starter positive, or a main power distribution point to sense the voltage to be controlled however NEVER jumpered directly to the Battery Postive on the back of the alternator. Can run a digital tachometer with a Dakota Digital SGI-100BT.ī: L- 12v ignition with a resistor with the option of adding a bulb(LAMP). Looking at the alternator 4-Way ConnectorĪ: P- Isn't normally used. These regulators are not typically setup for this application. F- Field Monitor: Used to externally monitor the rotor's magnetic field. **C usually also has an F next to the I on the same plug. Looking into the 4-Way Metripack plug on the harnessĪ: P- Phase/Stator: Drives external device such as an electric tach or hour meterī: L- Lamp/Regulator: Alternator warning lamp to an ignition 12v+ to excite the alternatorĬ: I- Ignition: Switched ignition 12v+ to excite the alternatorĭ: S- Sense: Sense the voltage to be controlled If you do not use the resistor, you will burn up the voltage regulator on your alternator. These alternators typically only need the Indicator Lamp (L) wire with a resistor hooked up to an ignition source as well as the Charge Wire and the Ground Point. An excite source is what is telling the alternator to start charging the battery. GEN III LS engines come from the factory with a self-regulating alternator that uses an external excite source. Below five ohms is an okay ground but the closer to zero the better.Īlternator Install Instructions from Powermasterĩ9-2005 Truck AD230 (small case) and AD244 (large case) Use an Ohmmeter to check the resistance to verify a good ground.

One of the best ways to get a good ground is bare metal to bare metal. If you do paint or powdercoat accessory brackets and/or the alternator, make sure you add a ground to a known good ground point. That's why our accessory brackets are NOT painted. The Ground Point comes from the mounting bolts to the alternator going through the bracket. Example wiring diagrams further below on the same page for NHRA guidelines. Keep in mind any rules and safety regulations you must follow for what you are building this project vehicle to do. The Charge Wire is connected to the Charge Post on the alternator and the wire goes to either the battery or the positive on the starter. However, if your application requires this, we can custom build alternators that are safely switchable.Īll GM SBC GEN III, IV, and V LS and LT engine alternators have at least a Charge Wire and a Ground Point. We do not recommend switching alternators on/ off while the engine is running. This causes severe internal spikes in the alternator, which could cause damage. Tech Tip From Powermaster: One wire alternators should NOT be 'switched', or isolated from the battery. A true 1-wire setup requires an alternator designed for just the charge wire. An 'Excite' source is something to tell it to start charging the battery. You will see and hear people talk about a 1-Wire plug to use on SBC GEN III, IV, and V swaps, but they still require an outside source to excite the alternator.

Do not confuse the term '1-Wire' alternator with the simple way to hook up your alternator that I will be going over later in this article. You can still run a true 1-Wire setup, but charging ONLY begins when they are at the 1200-1400 RPM's and may lead to issues especially when trying to charge at idle. The true 1-Wire setups used only a charge wire and grounding points. The term '1-Wire' carries over from 1-Wire alternators for SBC/BBC GEN 1 setups. One to the alternator plug and one to the battery post. In this article I go over how the alternators can be hooked up easily with just two wires to simplify your swap. GEN III Trucks began to recieve the 2-Way connector expecting the PWM signal in 2005. If you have any additional info you have experienced or come across that can help the next person, email us: GEN III engines typically came with a self-regulating alternator with a 4-Way connector (other than the 04 GTO) while LS GEN IV and LT GEN V engines typically come with an alternator with a 2-Way connector that is expecting a PWM signal from the BCM to tell it what voltage to charge the battery at. Proper installation is the responsibility of the installer. Use the following information to help out with your GM V8 swap project.

General motors 3 wire alternator wiring diagram