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 T1 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. The spade terminals at the rear housing 
should be marked  T1 & T2. 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 T1 terminal is on the left
 and the T2 on the right. You only need to run an ignition wire to the T1 terminal to
 make the Si alternator work. The T2 terminal is voltage sensing, this is an optional terminal. 
The T2 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 T2 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 T2 terminal directly to the
 battery connection at the back of the alternators, this is not needed.

The ignition wire to the T1 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 T1 terminal must be ignition 
switched. I have heard of situations where a wire was run to the T1 terminal that had power on
 at all times. What happens is when the engine is turned off the T1 terminal switches to 
ground which over time can burn up the voltage regulator or the wire if power is not cut to 
the T1 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 T1 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 T1 terminal. 
The DIODE will stop the power from feeding back up the ignition line.