"P" Series Motorhome
Vehicle uses electric automatic parking brake. It controls the drive shaft-mounted parking brake. The system consists of a pressure maintenance switch, electric/hydraulic pump, reservoir, high pressure actuator, solenoid valve, light switch, parking brake relay, and a cam actuated switch.
To release the electric automatic apply parking brake, move shift lever to Park. Movement is transferred from transmission shift linkage to cam actuated switch. See Fig 1. Cam actuated switch closes, allowing current flow to solenoid valve and pressure maintenance switch. Solenoid valve closes and holds system pressure. If system pressure is less than 1200 psi (83 kg/cm2 ), pressure maintenance switch closes and turns on pump motor.
When fluid pressure reaches about 1600 psi (110 kg/cm2 ) pressure maintenance switch opens and shuts off the pump. Fluid pressure overcomes spring tension and moves the actuator piston. Movement is transferred to the parking brake through a cable, and the parking brake is released. Moving shift lever to Park or turning ignition off de-energizes parking brake solenoid and dumps fluid back into reservoir. See Fig 1. As pressure decreases, spring in actuator moves piston and applies parking brake through the cable.
If system pressure is less than 450 psi (31 kg/cm2 ) or electric-hydraulic pump motor is running due to pressure maintenance switch being closed, AUTO PARK warning light comes on. Pressure maintenance switch and parking brake light switch supply battery voltage to auto park light circuit. Releasing parking brake opens the switches and turns AUTO PARK light off.