I posted an informational thread on LS1 forums about using GM 2006 and later 2 pin alternators. The thread became a sticky.
There were questions from Holley users about using these alternators. I don't have a Holley yet, but I looked over some Holley documents and gave some opinions. Hopefully Holley users can confirm or correct my opinions.

This alternator is PWM commanded. The PWM tells it what voltage to put out and the internal regulator takes care of all the rest. The reason GM did this is so their ECM/BCM can command the alternator to put out any voltage from 11V to 15.5V. Before the late model engine is started, and also after its shut off, GM can check the condition of your battery. Then they can decide how to charge it and they command the alternator to put out the voltage needed to maintain the battery. Also, the alternator tells the computer if it's having trouble putting out the voltage that the computer commanded. To help the alternator, the computer might raise the idle speed for example.



The L pin is the command voltage pin. A 5V PWM signal is sent from the ECM/BCM at a frequency of 128hz. If the duty cycle is less than 10% or more than 90% or just plain not connected, the alternator will go into default mode and put out about 13.7 volts. Enough to keep your car running, but not enough to charge the battery well. Here are the voltages and duty cycles:
10% = 11.0 V
20% = 11.56 V
30% = 12.12 V
40% = 12.68 V
50% = 13.25 V
60% = 13.81 V
70% = 14.37 V
80% = 14.94 V
90% = 15.5 V

The F terminal is also a PWM signal. But it's put out by the alternator and read by the computer. The lower the duty cycle the easier the alternator is working. If you want to use the alternator and aren't connected to the correct ECM/BCM then you don't need to connect the F terminal.

The only problem is that it needs a 5 volt PWM and I don't think Holley supports that directly. So I made the following suggestions.

Remember that for Holley PWM+ and PWM- duty required is opposite.

So let's say you want 14.37 volts above 400 RPM and you are using the PWM- port. Then try 85% across the board under 400 RPM and 30% across the board over 400 RPM and this wiring:



For PWM- these are the command percentages. Find your desired voltage and set that percent over 400 RPM
90% = 11.0 V
80% = 11.56 V
70% = 12.12 V
60% = 12.68 V
50% = 13.25 V
40% = 13.81 V
30% = 14.37 V
20% = 14.94 V
10% = 15.5 V

So let's say you want 14.37 volts above 400 RPM and you are using the PWM+ ......... Then try 15% across the board under 400 RPM and 70% across the board over 400 RPM and this wiring:


For PWM+ these are the command percentages. Find your desired voltage and set that percent over 400 RPM.
10% = 11.0 V
20% = 11.56 V
30% = 12.12 V
40% = 12.68 V
50% = 13.25 V
60% = 13.81 V
70% = 14.37 V
80% = 14.94 V
90% = 15.5 V

Let's say you have a boosted car and want higher voltage so your ignition and fuel pump when you are under boost. Then you might have a table RPM on one axis and MAP on the other to set the desired PWM, and therefore commanded alternator voltage. Once again, I don't have a Holley, so I can't test this.