MSD 8737 Three Step Module Selector

The MSD module selectors allow you to choose two or three different RPM limits that can be activated at different times. With this ability, the possibilities are endless. 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 V 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, the limit turns off.