speedo stopped working

[carls200tdi]

hi guys i've got a 1991 rangie turbo diesel went through some water today while laning and the speedo has stopped working evreything  else on the speedo works but not the speedo itself any ideas what could be at fault
 had a quick look at the speed transducer and the big nut on front of the transducer was only finger tight could this be the problem thanks

[Range Rover Blues]

Could be yes, the transducer is a magnet that spins and a reed switch that opens and closes, now that should be sealed in glass but you never know :roll:.

Easy to test though, jack up one wheel at each end and check for a 12 volt pules to the speedo head/engine ECU/cruise control/EAS (delete as appropriate).

BTW if any of these work as normal then the speedo is goosed for sure.