Your vehicle has either hydraulic or air brakes. Each system has different warning lights.

Vehicles with hydraulic brake systems have two brake system warning lights on the instrument panel.

If this light comes on, the fluid level in the master cylinder reservoir is low or there is a problem with the hydraulic brakes.

When it comes on, you will also hear a warning tone.

This light should come on briefly when you turn the ignition key to ON. If it does not come on, then have it fixed so it will be ready to warn you if there is a problem.

The brake system warning light may come on, and the warning tone may sound, when you are turning and braking at the same time. This is normal. See "Hydraulic Brake Systems" under Braking.

If this light comes on, it means there may be a problem with the brake system.

When this light comes on, you will also hear a warning tone. Have the system repaired immediately.

Both of these lights should come on briefly every time you start your engine. If they do not come on then, have them fixed so they will be ready to warn you if there is a problem. If one or both of these warning lights stay on after you start the engine, there could be a brake problem. Have your brake system inspected right away.

If one or both of these lights come on while you are driving, pull off the road and stop carefully. You may notice that the pedal is harder to push, or the pedal may go closer to the floor. It may take longer to stop. If the brake system warning light is still on, have the vehicle towed for service. See Towing Your Vehicle. See "Hydraulic Brake Systems" under Braking for further information.

This light will also come on when you set the parking brake. The light will stay on if your parking brake does not release fully.

Vehicles with air brake systems have a brake system warning light on the instrument panel.

The low air warning light should come on, as a check, whenever you start the engine. However, it is designed to come on, and stay on, when brake reservoir pressure has dropped below 60 psi (410 kPa).

When the warning light comes on while you are driving, you should drive only as far as the nearest point of safety and then stop the vehicle.

Caution: If the air brake system warning light comes on and the warning tone sounds, the vehicle can stop suddenly and without further warning. This is because the parking brake will come on if the pressure falls below 35 to 45 psi (240 to 310 kPa). You or others could be injured. If the air brake system warning light comes on and the warning tone sounds, stop as soon as you can. You will not know how quickly the system is losing pressure, so be aware that the parking brake may come on suddenly.