What should be done if the fifth wheel does not fully lock during the tug test?

If the fifth wheel does not fully lock during the tug test, reversing again to engage is the recommended course of action. During a tug test, it's crucial to ensure that the fifth wheel has properly locked onto the trailer kingpin to prevent any separation while on the road. If the fifth wheel has not locked, simply moving the vehicle forward may not resolve the issue, and actively reversing can help ensure that the kingpin aligns correctly with the fifth wheel locking mechanism.

This action allows for a more secure coupling, as the locking mechanism needs the correct alignment to function properly. If the problem persists after attempting this, further action, such as inspecting the trailer pin or the coupling device, might be warranted to ensure safe operation. Continuing to drive without resolving the issue poses significant safety risks, and replacing the coupling device would typically be considered only if no other solutions rectify the problem.