It should have and if not should be fitted with one as it would not pass a Certificate of Thorough Examination.
Have you got the serial number of year of build as I can check? It may also be the park brake switch at fault as some, depending on year have the park brake switch linked into the seat switch wiring.
Are you an fork truck engineer? if not please be carefull when doing any electrical fault finding and make sure the drive wheel are jacked up!