Comanche 4WD L6-242 4.0L VIN L FI (1990)
Fuel Pump Ballast Resistor: Description and Operation
Fuel Pump Ballast Resistor
The fuel pump ballast resistor is placed in the circuit between the fuel pump relay and fuel pump. It is used to reduce fuel pump noise. Voltage to the
fuel pump is supplied through the ballast resistor under all operating conditions except wide open throttle. When the vehicle is under a wide open
throttle condition, the ballast bypass relay is grounded (ENERGIZED) by the engine controller. When the ballast bypass relay gets ENERGIZED,
voltage bypasses the fuel pump ballast resistor and full system voltage is applied to the fuel pump.
Voltage to the ballast bypass relay is supplied through the fuel pump relay. The fuel pump ballast resistor is located next to the washer fluid reservoir.
