ASE Automobile and Light Truck Certification Manual Transmission (A3) Practice Test 2025 - Free Manual Transmission Certification Practice Questions

Automatic locking hubs on a light truck may not disengage if either an incorrect shifting procedure is used or if there's a wrong locking washer behind the wheel bearing lock nut.

When it comes to shifting procedures, automatic locking hubs rely on specific vehicle movements and input from the driver to properly engage and disengage. If a driver does not follow the correct sequence—such as shifting in and out of four-wheel drive while the vehicle is in motion or not allowing the vehicle to come to a complete stop—this can impede the ability of the hubs to disengage.

On the other hand, a wrong locking washer behind the wheel bearing lock nut can also lead to a failure of the automatic locking mechanism. The locking washer is crucial in maintaining the proper alignment and securing necessary components within the hub assembly. If the washer is incorrect, it may not allow the hub to operate as designed, which can prevent disengagement.

In combining these two points, it is clear that both factors can independently contribute to the issue of automatic locking hubs not disengaging. This highlights the importance of both procedure and correct components in the functionality of a light truck's locking hub system.