Toyota 47900-35491 Valve Assy, Load Sensing W/Spring

Most of an empty truck's weight stays in front, with its center of gravity higher than on cars. As brakes work, the vehicle tilts forward onto its front tires due to its higher height and front weight, unloading the back end, which requires more hydraulic power for the front brake and less for the rear to stop wheels from locking up. The underside of trucks holds a special valve set, the LSP & BV, which detects bed cargo weight to alter front/rear brake pressure automatically. Before you work on brakes, make sure you protect your vehicle's paint job from brake fluid by putting coverings over any parts that are painted. Homeowners should not try to service the LSP & BV because it uses a specialized gauge set, but you can replace broken parts. Adjustments have to be done by a car dealership or certified repair shop. When you take out the rear axle, you must disconnect the height sensing rod from it, but make sure you keep the rod's current setting. Before working on this system, put the car up on jackstands, loosen the tube nuts at the brake line with a flare-nut wrench, move each brake line away slightly and plug them to protect against dirt, remove the bolt holding the adjustment arm to the suspension, uninstall the LSP & BV mounting bolt, and disconnect the LSP & BV from the bracket. We put the spring back to how it started, adjust the locknut until everything is in place. At the end of repair, have brake fluid drained and get the brake system checked at a dealer or repair shop specialized in working on vehicles like yours.