hi Geo, got the buzzer you suggested but unfortunatly your info was wrongoh: 5 wire system. power in/out to left indicator power in/out to right indicator common earth. (presumably for relays !) if its connected to cab end wiring the buzzer will sound regardless of trailer/toad attached or not. it must be connected between 7core cable and van indicator wires. ie: no toad attached = no earth/continuity through toad bulb = no buzzer. connect at flasher unit will mean an earth/cont will be present through M/H indicator so it will sound when M/H indi's are used. :Sad: (unless you know a dsifferent way) its a long way from the rear end to the drivers seat and the buzzer aint that loud. no big shakes though as it was only £2.75. thanks for the link all the same. :thumb:. john.