Being quite a late Series 3 unfortunately that contract is not one of the 18 contracts listed on my particular EMER Technical Summary Data Sheet. I think the best way ahead is to join the Military Vehicle Trust as they have a vehicle...

I just wondered as I didn't know what authority you were up against. Your 109 is it a Rover 9 or 11 or Series 3? If you have the contract plate with a Contract No. & Asset Code it will tie in with Technical Data Summary of the relevant EMER that...

I would first check that you are getting turn light voltage from the NATO socket on the vehicle. M - LHS N - RHS Then if that is OK check the earthing is good on each of the trailer earths for the turn lights.