STEERING VALVE AND MOUNTING GP. 7U7205 - Caterpillar

Table 1
Problem: Parking Brake Actuation Pressure Out of Specifications
Possible Component Root Causes Non-Component Root Causes How to Diagnose Corrective Action
Relay Valve for the Parking and Secondary Brake Contamination Release parking brake and measure pressure park brake retract pressure. If the pressure is out of spec ( 4600 800 kPa (667 116 psi)), follow corrective actions. Service with new relay valve for the parking and secondary brake. Make sure that oil is ISO 18/15 or better.
Solenoid Valve for the Parking Brake Contamination Service with new parking brake solenoid valve. Make sure that oil is ISO 18/15 or better.
"AETA/TCS" Valve Contamination Check to see if the "AETA" self test is working properly. Ensure that the left and right rear parking brake pressure increases and decreases smoothly. If one side does not cycle completely, then inspect and repair the "AETA" valve. Service with new "AETA" valve. Make sure that oil is ISO 18/15 or better.
Relief valve Stuck open Contamination Brake Pump stalled at accumulator pressure. Replace or reset Relief Valve.
Brake Pack Over pressurization Apply parking brake and measure the pressure at the brake packs. All four pressures should be within tolerance. Replace if one or more brake packs are lower than the others. Inspect for seal damage.