MM-VC1 Instructions

MM-VC1 Instructions

Posted by Mechman on 25th Oct 2023


 Voltage Controller MM-VC1

For 2005 & later GM Application Alternators 


          with 2-Pin Harness Connection



First contact technical support at:  1 (888) MECHMAN



Works only with alternators with this 2-pin harness connection on GM vehicles

 Application note:






  • Eye protection must be worn when working on batteries.
  • Remove all jewelry before working on the electrical system.
  • Always refer to a service manual for specifics about your vehicle’s alternator installation and electrical system.
  • The MM-VC1 controller is not waterproof and should be mounted inside the passenger compartment away from any heat source.
  • One MM-VC1 may control up to four (4) alternators.  Custom wiring for this application is required.  


Installation steps:


  1. Turn off engine and let it fully cool.


  1. Disconnect the negative cable from the battery/batteries.


  1. Mount the controller (optional)



  1.  Wire controller as shown below.  


Note:  Be sure the P103 module is installed, or a charge alert will show on the instrument cluster.


Firewall grommet:  Wires passing through the firewall must be protected by a grommet.  Either a hole can be drilled and a grommet installed or the wire can be routed through an existing grommet.  Take care not to damage any existing wiring.