What I suggest is that you edit your post (those three dots, bottom right of your post > Edit) to include a link to the mod you are talking about (type the mod name & then highlight the text then hit the infinity figure of 8 symbol above text box & then paste link).
It will then appear like this
There are many lighting mods out there, so it may be that you require a specific lighting mod installed as well as the vehicle & carcols in the right place to get the lights to work.
Carcols are usually installed in the 'dlc.rpf' that comes with a mod. Internal file location can vary so I'll have a bit more of an idea once you link to the mod in question.
I added the vehicle as a new DLC mod and all is good now!! Lesson learned here as I will do this procedure moving forward to avoid any errors. thanks for reply though