Ballast Resistor

Cherokee and Comanche models have a ballast resistor located between fuel pump relay and the fuel pump. Its purpose is to reduce voltage to the fuel pump. This reduces fuel pump noise during operation. Ballast resistor is mounted on fender panel, next to washer fluid reservoir.

When fuel pump relay is energized, voltage is supplied to fuel pump through the ballast resistor. During start and wide open throttle conditions, ballast resistor is by-passed and fuel pump receives its voltage from ballast resistor by-pass relay.