You’re about to start a journey towing a trailer. What should you do if you notice that a light on your trailer is not working?

Explanation: You must make sure that your vehicle and trailer are roadworthy. Check that your tyres are legal, and the brakes and lights are working properly.
If any of these things is not working, you must not drive or tow your trailer until the fault is repaired.

Category: Vehicle loading

References: Highway Code: Rule 98