What should be the gear of the engine after coupling a trailer for inspection?

After coupling a trailer for inspection, the engine should be in neutral. This is important because neutral allows you to inspect the trailer without the risk of the vehicle moving unexpectedly. By keeping the engine in neutral, you can safely check the connections and ensure everything is secured properly without engaging the transmission.

If the vehicle were in drive or reverse, even by inadvertently pressing the accelerator, it could lead to a dangerous situation, potentially causing the vehicle to move while you are inspecting the trailer. Similarly, placing the vehicle in park does not provide a safe environment for inspection since it can still roll slightly if on an incline or if not properly secured. Therefore, neutral is the safest gear to use after coupling a trailer for inspection, allowing for stability and safety during the process.