Hydraulic System Junction Block: Description and Operation
JUNCTION BLOCKDESCRIPTION
A junction block is used on vehicles that are not equipped with Antilock Brakes (ABS). The junction block is located on the left side of the lower radiator support (Fig. 44). The junction block mounts in the same location as the ABS Integrated Control Unit (ICU) does on vehicles with ABS.
It has six threaded ports to which the brake tubes connect. Two are for the brake tubes coming from the master cylinder. The remaining four ports are for the brake tubes going to each brake assembly. The valve is permanently mounted to a bracket which fastens to the lower radiator support.
The junction block includes two proportioning valves for the rear brakes. One valve is mounted in each end of the block (Fig. 44). The proportioning valves are not serviced separately from the junction block.
OPERATION
The junction block distributes the brake fluid coming from the master cylinder primary and secondary ports to the four brake tubes leading to the brakes. Since the junction block mounts in the same location as the ABS Integrated Control Unit (ICU), it allows for the common use of brake tubes on the vehicle whether it is equipped with or without ABS.
The junction block includes two proportioning valves. Placed in the fluid flow passages leading to the rear brake tube ports, they balance front-to-rear braking.