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Hey guys, I am of the group that loves the one wire for its simplicity however my current project has a 3 wire, and I was curious how to wire this, any help would be apreciatted.
GM alternator?
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chopper tom
Way too young to be a hippy!
see my GMwiring question in the elctrical section of this forum.
Alienbaby sent the info.
Alienbaby sent the info.
freakdude
Well-known member
Speedway has a harness that would change it over to a one wire!
falconvan
Well-known member
Here's a good article on the subject...
How do I wire a GM (Delco-Remy) alternator to make it work
Wiring the Si series alternator
General Motors has only had 4 different series alternators since it first replaced generators with alternators in the 1960's.
The very first alternator was the 10-DN externally regulated alternator. The first internal regulated alternator was the 10-Si
series starting in the early 70's and used till the mid 80's. These alternators have been quite popular for auto, truck,
industrial, marine, farm and adaptive applications. Since the introduction of the 10-Si GM's Delco-Remy had offered the
12Si, 15Si, 17Si, 27Si then the CS and AD series alternators for car & light trucks
This first section will cover wiring information for the SI series only, we will go over the CS and AD series wiring later.
Although they may vary in size and output the wiring is the same for all the Si series, wiring these alternators is quite simple.
All the Si alternators can be considered both 2 and 3 wire systems. To activate these alternators you are only required to
supply the main battery wire to the (BAT) terminal which must have power on and an ignition wire to the #1 terminal.
Most all the Si series alternators should have two spade terminals, but some that have three terminals, the third
is for a tach connection. Near the spade terminals the rear housing should be marked #1 & 2. Some aftermarket
housings are not marked and others may be worn off, so if yours is unmarked, looking from the rear of the alternator
the #1 terminal is on the left and the #2 on the right. As I said earlier you only need an ignition wire to the #1
terminal to make the Si alternator work. The #2 terminal is voltage sensing, this is an optional terminal. The #2 voltage sensing
terminal is for the voltage regulator to sense what voltage the battery is at so it knows when to turn the alternator on and off.
The reason the #2 terminal is optional is that if it is not used the regulator reverts to internal sensing and picks up the
battery voltage at the main battery wire on the back of the alternator. I've seen alternators wired with a jumper from the #2
terminal directly to the battery connection at the back of the alternators, this is not needed.
The ignition wire to the #1 terminal can be supplied in two ways, either a direct ignition wire from the key switch or through a
light bulb. Running the ignition wire through a light bulb before connection to the alternator will give you a warning if your alternator
fails to start charging or if it quits working while the engine is running, this is commonly known as the idiot light. Another thing that
should be mentioned is the #1 terminal must be ignition switched. I have heard of situations where a wire was run to the #1 terminal
that had power on at all times. What happens is when the engine is turned off the #1 terminal switches to ground which over time
can burn up the voltage regulator or the wire if power is not cut to the #1 terminal.
Another note for special installations of the Si series alternator is that in some cases when you try to shut the vehicle off it continues to run.
This is caused by the fact that once the alternator starts charging the voltage regulator switches the #1 terminal from ground to positive power, the plus power feads up to the coil and keeps the vehicle running.
To cure this you must install a diode in the ignition wire that activates the #1 terminal. The diode will stop the power from feeding back up the ignition line.
How do I wire a GM (Delco-Remy) alternator to make it work
Wiring the Si series alternator
General Motors has only had 4 different series alternators since it first replaced generators with alternators in the 1960's.
The very first alternator was the 10-DN externally regulated alternator. The first internal regulated alternator was the 10-Si
series starting in the early 70's and used till the mid 80's. These alternators have been quite popular for auto, truck,
industrial, marine, farm and adaptive applications. Since the introduction of the 10-Si GM's Delco-Remy had offered the
12Si, 15Si, 17Si, 27Si then the CS and AD series alternators for car & light trucks
This first section will cover wiring information for the SI series only, we will go over the CS and AD series wiring later.
Although they may vary in size and output the wiring is the same for all the Si series, wiring these alternators is quite simple.
All the Si alternators can be considered both 2 and 3 wire systems. To activate these alternators you are only required to
supply the main battery wire to the (BAT) terminal which must have power on and an ignition wire to the #1 terminal.
Most all the Si series alternators should have two spade terminals, but some that have three terminals, the third
is for a tach connection. Near the spade terminals the rear housing should be marked #1 & 2. Some aftermarket
housings are not marked and others may be worn off, so if yours is unmarked, looking from the rear of the alternator
the #1 terminal is on the left and the #2 on the right. As I said earlier you only need an ignition wire to the #1
terminal to make the Si alternator work. The #2 terminal is voltage sensing, this is an optional terminal. The #2 voltage sensing
terminal is for the voltage regulator to sense what voltage the battery is at so it knows when to turn the alternator on and off.
The reason the #2 terminal is optional is that if it is not used the regulator reverts to internal sensing and picks up the
battery voltage at the main battery wire on the back of the alternator. I've seen alternators wired with a jumper from the #2
terminal directly to the battery connection at the back of the alternators, this is not needed.
The ignition wire to the #1 terminal can be supplied in two ways, either a direct ignition wire from the key switch or through a
light bulb. Running the ignition wire through a light bulb before connection to the alternator will give you a warning if your alternator
fails to start charging or if it quits working while the engine is running, this is commonly known as the idiot light. Another thing that
should be mentioned is the #1 terminal must be ignition switched. I have heard of situations where a wire was run to the #1 terminal
that had power on at all times. What happens is when the engine is turned off the #1 terminal switches to ground which over time
can burn up the voltage regulator or the wire if power is not cut to the #1 terminal.
Another note for special installations of the Si series alternator is that in some cases when you try to shut the vehicle off it continues to run.
This is caused by the fact that once the alternator starts charging the voltage regulator switches the #1 terminal from ground to positive power, the plus power feads up to the coil and keeps the vehicle running.
To cure this you must install a diode in the ignition wire that activates the #1 terminal. The diode will stop the power from feeding back up the ignition line.
wire the red wire from the flat 2 wire plug to large post on back of alt. then wire smaller white wire in the 2 wire plug to a 12volt power when key on source.the large post can be wired either directly to battery positive or to power feed to starter whichever is easier or cleaner to do
