Automobile & Light Truck Certification Test A5 BrakesAnti-lock Brake System (ABS) Diagnosis and RepairMedium
A vehicle with electronic stability control (ESC) begins to oversteer during a turn. Which of the following is the MOST likely action the ESC system will take to correct this condition?
- AApply the brakes to the outside front wheel.
- BReduce power to the rear wheels while applying the brakes to the outside front wheel.
- CIncrease engine power to the front wheels.
- DApply the brakes to the inside rear wheel.
Show answer & explanationAnswer & explanation
Correct answer: A. Apply the brakes to the outside front wheel.
Oversteer occurs when the rear of the vehicle slides out. To correct this, the ESC system will typically apply the brake to the outside front wheel. This creates a yaw moment that helps 'pull' the front of the vehicle back into the turn, counteracting the rear's outward slide.
Why the other options are wrong
- B. While reducing power can be part of ESC, applying brakes to the outside front wheel is the primary corrective action for oversteer, not a combination with brakes to the outside front.
- C. Increasing engine power would likely worsen the loss of control, especially during oversteer.
- D. Applying the brake to the inside rear wheel would exacerbate oversteer by further pushing the rear out.
ESC Oversteer Correction
Electronic Stability Control's method to counteract a vehicle's rear end sliding outwards in a turn.
- Detects oversteer using yaw rate, steering angle, and wheel speed sensors.
- Primarily applies brake to the outside front wheel.
- Creates a counter-yaw moment to bring the vehicle back in line.
Memory trick: Oversteer is a spin, so brake the outer front to pull it back in!