ABS for Early Subaru Part 4:

Measuring Brake Pedal Travel:

The difference between the two distances (pedal depressed, pedal released) must be less than 3.75 inches (95 mm). If it is greater than that, there is air trapped in the HCU. Expel this air using Sequence Control.

Sequence Control:

Sequence Control is the name of a mode in which the system automatically runs the HCU pump motor and cycles the solenoid valves. The Sequence Control actions help to purge air out of the hydraulic control unit.

To activate Sequence Control, proceed as follows:

• With the ignition off, jumper both the “L” and “K” terminals in the ABS check connector to ground.
• Turn the ignition switch to On and watch the ABS warning lamp.
• When the lamp goes off, immediately press and hold the brake pedal.
• The ECU now runs the pump and cycles all the solenoid valves. You will hear and feel this happening. • When you hear the pump stop, you know Sequence Control is done.
• Release the brake pedal and turn the ignition to Off.

When you have completed Sequence Control, bleed all four brake circuits again. Top off the master cylinder reservoir after bleeding each circuit. Then road test the vehicle at low speed. Apply the brakes hard two or three times to make sure the brakes are working properly.