Wagoneer L6-242 4.0L VIN M FI (1988)
Brake Fluid Pressure Sensor/Switch: Description and Operation
Low Pressure Switch
Fig. 14 Low Pressure Accumulator Switch
LOW PRESSURE SWITCH
The low pressure switch is a single pole, single throw switch. The pressure switch is grounded to the body during normal operation. However if
pressure drops below a specified amount (approx. 1050 PSI) the. switch opens signaling the Electronic Control Unit (ECU) of the low pressure
condition. The ECU will then illuminate the yellow light on the instrument panel and after a 20 second delay the red light will illuminate to signal
the driver of a brake system problem.