What it does
Anti-lock brakes (ABS) stop the wheels locking under hard braking, so you can still steer. You will feel the pedal pulse; keep pressing firmly.
Traction control stops the drive wheels spinning when you accelerate on a slippery surface, by cutting engine power or braking the spinning wheel.
Electronic stability control (ESC) notices when the car begins to slide sideways, nose first or tail first, and brakes individual wheels to bring it back in line. Passenger vehicles sold in the United States have been required to have it since the 2012 model year.
How it senses
A speed sensor at each wheel, a sensor that reads the angle of the steering wheel, and a yaw sensor that measures how fast the car is turning. When the turn the car is making does not match the turn you are asking for, the system steps in.
What sets it off
Wet, icy, gravel or leaf-covered roads, a fast swerve, or a corner taken too quickly. While the system is working, the symbol of a car with wavy lines behind it flashes on the dashboard.
Where it stops
- It cannot create grip that the tires do not have. Worn tires, the wrong tires for the season and low pressure all leave it less to work with.
- Too much speed for the conditions is still too much speed.
- If the symbol stays on steadily, or appears with the word OFF, the system is switched off or has a fault.
Check for your car
- How to switch traction control off, and when your manual suggests it. Rocking a car out of deep snow or mud is the usual reason.
- Whether switching it off also switches off stability control.
- Whether it turns back on by itself above a certain speed or at the next start.
Switch it back on as soon as you are moving again.
This guide describes how the system generally works. Makers tune and name their systems differently, so your owner’s manual is the final word for your vehicle.
Next guideAirbags and Restraints
