A flow switch in the hydraulic booster pressure hose closes when the pressure becomes too low for hydraulic booster operation. When the switch closes, the BRAKE Lamp lights on the instrument cluster.

Notice: Hydraulic brake systems use two distinct and incompatible fluids. Power steering fluid is used in the hydraulic brake booster system. Brake fluid is used in the master cylinder and brake pipes. Use extreme care when selecting brake system fluids, or seal damage can result. Refer to General Information to select the correct fluid.

Use the correct fluids. The master cylinder and brake system use brake fluid. The power steering pump and the hydraulic booster system use power steering fluid.

Check the fluid level in the power steering pump reservoir at regular intervals. Add fluid when necessary. Refer to Maintenance and Lubrication.

Do not reuse brake system fluids. Do not mix power steering fluid with brake fluid. Fluid contamination may result in swelling and deterioration of rubber parts. This can lead to reduced brake performance and the eventual loss of braking capability.

If contamination occurs, flush the hydraulic booster system. Flushing the system involves draining the old fluid and replacing that fluid with clean fluid. Refer to Flushing the Power Steering System in Power Steering System.

Service booster components in a clean work area separate from the brake servicing area. Wash hands before changing work areas. Do not use the same containers for brake and power steering fluids.

Flushing is required when you find dirt, sludge, or water in the system. Flushing is running clean fluid through the system until the draining fluid appears the same as clean fluid. Contaminated fluid in the booster system can cause rubber parts to deteriorate.