JCV file for 2017.30

.. the current map is 2018.10 ... if you update you'll get the correct file.

But yes, the 14xx series doesn't use split view and the device will use the correct file.

I've got two folders in the "additional files" bit, one called JCV_FullScreen and one called JCV_LaneAssistFull. The latter has the larger file.
I've a 1490 which doesn't do split screen junction view - do I still need to copy both JCV files into the JCV folder or just the larger one?
I have read the guidance on here but still can't make head or tail of it, and don't understand why the smaller one (which I would assume is the split screen view) is called Full Screen while the larger Junction view file is called Lane Assist, though I have noted that Garmins file naming conventions can be a bit odd.

... did those files/folders get there? I've never seen that naming on my 1490, or indeed any nuvi. Normally there would be a folder named JCV with a file inside it. If it were me I'd delete the lot and update your map, assuming you have lifetime updates?

One possibility is that you're getting your maps, files etc from non Garmin sites, in which case you won't get any help here.

As "sussamb" mentiones, WHERE did you get your map and the JCV files?