New Epb Features - Subaru Legacy 2015 Technicians Reference Booklet

2015 Legacy and Outback

New EPB Features

The Sliding Prevention feature of the EPB allows for self activation of the EPB motor to increase
the tension to the brake pads, if the parking brake had been previously set. Sliding Prevention
is activated if the wheel speed sensors detect vehicle movement within 15 minutes of the EPB
activation.
The Temperature Compensation feature of the EPB functions by calculating brake component
temperature from information obtained by the CAN and HCU. The Ambient air temperature, vehicle
speed, road incline, service brake use frequency, and other vehicle information are considered
when calculating brake component temperature. Higher temperatures equate to expanded parts
which will contract as they cool. This could produce a situation where the initial EPB activation is
not strong enough to maintain vehicle position. Compensation for high temperature is achieved
by two methods;
1. The EPB is activated with the Engine operating or CAN still operating. All necessary data is
available to the EPB control unit (HCU) and the EPB motor applies additional mechanical
force to the brake pads.
2. The EPB is activated with the Engine off and the CAN in sleep mode. Data to determine
brake component temperature is not available to the EPB control unit (HCU). The initial EPB
activation will be limited to learned values. An additional application of the EPB motor will
be self activated by the EPB control unit (HCU) 2 minutes and 30 seconds after the EPB
was initially set. This will tighten any clearances that may have developed from contracting
brake parts.
An Automatic adjustment procedure is performed if no EPB operation is detected. The EPB control
unit (HCU) monitors the driving mileage and will self activate the EPB with the engine off once
every 1864 miles (3000 kilometers). This procedure repositions the ball nut clearance from the
back face of the hydraulic piston and tests the EPB motor drive circuits. The EPB will remain on
after the adjustment. EPB release is accomplished with the automatic release feature or manual
release while pressing the brake pedal.
New Technology Training
136
(Module 926)
June 2014