Are your trailer lights working?

The job of checking a caravan’s road lights is not easy for the lone traveller. It is simpler when an assistant is available to call out that the various lamps are working. I heard of one independent caravanner who carried a piece of wood that he would wedge between the driver’s seat and brake pedal to keep the stop lights operating while he went round the back of his unit to check! The circuit published here will help anyone to test their trailer’s lights without assistance (in fact, a request was made for such a device in Readout (EPE December, 2004).