I’ve just received my 13pin plug and play trailer electrics and in the instructions it says remove battery negative, is this necessary as it a case of unplugging the 7 pin connecter and plugging in the 13, car has been told it’s got a towbar is there a different setting for 13pin electrics over the 7pin 2012 Range Rover Westminster 4.4 TDV8
2006 Discovery 3 HSE 260k miles and still going strong with a new owner

I just unplugged mine and plugged the new 13pin into the big grey plug.
Good luck getting the cross member rubber grommet into place. Use some lube
It's plug and play on later models so no need to update CCF on car etc.
I use mine for battery charging via a CTEK adaptor and not towing  2011 4.4 TDV8 Vogue SE Buckingham Blue with Ivory and clear glass = "Rory"
New Defender D300 90 on order so "Rory" will be going to a new home....!
1974 Series 3 Lightweight = "Millie"
My preferred specialist: www.glenrands.co.uk
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To be fair it went well, the plug in the car went through the hole in the crossmember so i was able to wire it all up on the bench and fit to the tow bar then simply pass the plug through the hole, a little grease on the grommet and it popped into place only problem is i went to push my 13-7 adapter in and it wouldn't go in the three pins and the slot just didn't line up and it feels solid and i assumed they twist on, should the inside of the adapter spin, sorry for my ignorance but i haven't used these before 2012 Range Rover Westminster 4.4 TDV8
2006 Discovery 3 HSE 260k miles and still going strong with a new owner

I’ve had difficulty with my adapter too. The L405 needs one while the L322 has the N and S setup. One day I ended up taking the l322 as I couldn’t get the plug in the 13pin in the L405! The adapter does spin in the casing but mine was a bit difficult. I put some lube on it and worked it round gently with some long nose pliers. It makes it easier to plug in now.