Disco 4 (LR4) Dif lock

So I have a 2016 discovery. I use it on a beach to launch a boat. Unusual I need all its off road skills. There is loads of soft sand I need to tow a heavy boat over I have it on sand setting but nearly got stuck due to inappropriate tyres. But I had the screen to show dif lock and at no time did I notice it actually locking on the screen Is there a way to test or check the function.

I have a icarsoft obd reader.

Which diff, axle or TB? Where you expecting to lock.

which terrain program?

J

I think they all show the rear diff lock, but very few actually have it fitted, probably one of the rarest options.

In future you might want to consider "airing down".
In the same circs!!
(you'll need to carry a small tyre compressor!)

I don't think a D4 is ideally suited to soft beach work, as it's just too bloody heavy, and so sinks in the sand. You must have seen the countless number of big LRs stuck on soft beaches surrounded by the rising tide.
The centre diff is lock on demand, unless it's in rock crawl mode IIRC.
Rear diff lock was an expensive factory option though.
The screen shows it locked, but in reality, it's only the ABS system helping out when needed.

Very sad story about a couple in the bush in Australia. They got stuck in sand couldn't drive their 4x4 out. so the bloke stayed with the vehicle and the woman went off to walk out and get help. She took as much water as she dared.
She died, he survived and when they came to recover the vehicle the mechanic just let a bit of air out of the tyres and drove it out.
Works on all sorts of soft surfaces.
https://www.google.com/search?q=air...57j0i512l9.4799j0j15&sourceid=chrome&ie=UTF-8
And of course there are all the things you can put around a tyre to improve its grip.