MSD Three-Step Module Selectors. MSD 3-step module selectors are designed for great versatility. They feature three built-in rev limiters--one for burnout, one for starting line launch, and one for high end. These selectors use the MSD plug-in rpm modules. Warranty. Recommended for You.. MSD, 3-Step Module Selector 3-Step Module Selector MSD 3-Step Module Selector Allows you to choose two or three different rpm limits that can be activated at different times. With this ability, the possibilities are endless. For example, by connecting one wire to the line-lock circuit, one module will be activated during the burnout.
Two Step, PN 8739 Three Step, PN 8737 The MSD Module Selectors provide the ability to switch between two or three different rpm or degree modules. The different modules are activated when 12 volts are applied to the corresponding activa-tion wire. The Selectors work with either a Soft Touch Rev Control or any MSD Timing Control that uses plug.. As an example, we'll use a drag car with a Three Step Module Selector plugged into the rpm socket of a 7AL-2 Ignition. The different rpm modules are activated when 12 volts are applied to a corresponding wire. By connecting one wire to the line-lock circuit, one module will be activated during the burnout. This helps keep tire temperatures consistent. When the line-lock button is released.