The rear wheels of an unloaded vehicle equipped with an automatic load-dependent braking force regulator (ALB) lock each time the brakes are strongly applied. What can be the cause?

Your answer is correct because both options 1 and 2 explain why the rear wheels might lock during strong braking in a vehicle with an automatic load-dependent braking force regulator (ALB).

The ALB is designed to adjust the braking force on the rear axle depending on the vehicle's load. If the ALB is defective or incorrectly adjusted (option 1), it may apply too much braking force to the rear wheels, causing them to lock when braking hard.

Additionally, if several spring leaves on the rear axle are broken (option 2), the vehicle’s suspension and load distribution are altered, which can confuse the ALB system and lead to excessive braking force being applied to the rear wheels, again causing them to lock.

Option 3 (strong fading of the brakes) does not directly cause the rear wheels to lock; brake fading generally reduces braking efficiency rather than causing wheel lockup.

Understanding how the ALB system functions and how vehicle suspension affects braking is important to diagnose such problems correctly.