We get so many messages stating "My VCM won’t adjust", "My VCM isn't working", this VCM is a piece of junk".... so, here's a quick tutorial on how to connect a very simple piece of equipment - the XS Power "VCM"


We think the reason it gets overly complicated is from the overabundance of harnesses/plugs all over the place that they send with the VCM & the lack of explanation of how it actually works. Combine that with several different models that all function slightly different, yet basically all the same, with different DIP switch settings & it's easy to get lost


The 1st thing I would do is throw away all harnesses they send - other than the main control panel harness, Keep that

  • · You may need to use the male regulator plug(s) they send if you don't already have them from your alternator supplier which is hopefully Iraggi Alternator, if not, now is a good time to upgrade!


I’ll start with a single alternator setup in something like a 99 Tahoe, Suburban, etc...

  • · You will NOT use the factory plug that is currently in the vehicle (It will eventually be cut clean off) It lacks the wires you need for the VCM to function


The ONLY difference is the colors & quantity of wires


The one on the right is the most common & "correct" color designation & also the one you’ll get from Iraggi Alternator


The one on the left is the XS Power version


  Ignore the colors of the XS Power version throughout this write up  


The  Blue  wire is "Sense" & the Yellow is "L" or "light" or "Lamp". Whatever you want to call it, but it is what turns the alternator on and off. Contrary to widespread belief, an alternator NEVER actually stops "charging"

  • The  Blue   Yellow  are the minimum wires you will need. Some vehicles add the "F" and "P" terminal but for sake of simplicity we will wait till the end to discuss optional wires

  • · You will cut the factory L terminal wire, which is probably Brown, & connect it to the Yellow wire on the Iraggi plug... which again is the "L" terminal.

  • This  Orange  wire is the VCM signal output - This goes to the Iraggi  Blue  wire on the plug that goes into the al

At this point you have a functional alternator again, but no power to the VCM yet - Your alternator will charge but will NOT be adjustable at this point

  • The VCM will now need its own Remote, Power & Ground connections - Black is obviously Ground & I recommend using the front battery terminal for this connection

  • The  Yellow  is constant power - I would go to the stud on back of the alternator for this one. I want to sense the source of power, not the amplifier. I like a secondary voltmeter directly at the rear battery bank just for informational/troubleshooting purposes, but I don't want the VCM connected/reading from there

  • The  Red  wire is the turn on for the VCM & goes to straight ignition


So now the only thing left are the control panel settings themselves - You can look at your owner’s manual & figure that part out - It’s straightforward


IF your vehicle used more than just the L terminal, make sure your alternator supplier sends you a complete harness with the other wires & simply connect them from the remaining wire on the stock harness to the new harness



The ONLY two wires you will use are the Yellow & Blue


You have two options on the  Yellow  ....


1. You can either try & parallel all the L terminals together, which is what I do on my Suburban with 6 alts


2. You can power up all the additional alts with a 470Ω resistor & an ignition source. I use one resistor per alt. I've seen where the factory L terminal won't turn on more than one or two alternators.... so, in that case get some resistors & find ignition... but keep one alt directly connected to the factory L terminal


Now you can parallel ALL the  Blue  wires together.

  • The VCM can be connected to as many alts as you want. There is no limit. It’s just a signal that has no current draw to speak of

  • The VCM is NOT a regulator... All it does is send a signal to the internal regulator to adjust its original factory preset voltage... which is typically 14.8 ish'


If you have any questions, please don’t hesitate to contact us…