could someone please the me were the main ECU is on my 2008 rrs

It's between the battery and the cabin firewall. You need to remove the battery to access the ECU box. The box includes the transfer box control module. 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed

Not sure for that year, but following should find it.
It should be under the bonnet in engine compartment at the back, where brake fluid reservoir is for checking and filling. You have to remove the black plastic type cover off by by windscreen, removing the four screws/clips depending on model.
Generally drivers Side, although I believe it can be on either side just for added confusion. Sorry, hope that slightly helps.

EDIT. Typed reply to slow, Well done RRST.  John

RRS MY12 SDV6 HSE. Sumatra Black/Ebony & Walnut + Dynamic Pack, + Cold Climate Pack + Memory Pack, Digital TV/DVD, Premium Leather, Cornering Lights, Cooler/Fridge Box, & most Options.

Last edited by Johnski on Wed Oct 18 2017 8:31pm. Edited 1 time in total

On Battery left side.

Assuming you want engine Ecu

Just found this photo install/removal guide on web.
http://www.fabspeed.com/templates/__custom...0Guide.pdf John

RRS MY12 SDV6 HSE. Sumatra Black/Ebony & Walnut + Dynamic Pack, + Cold Climate Pack + Memory Pack, Digital TV/DVD, Premium Leather, Cornering Lights, Cooler/Fridge Box, & most Options.

Thanks alot, so I'll just put this one back under the drivers seat

One under drivers seat is normally the amplifier for the Harman Kardon stereo system. John

RRS MY12 SDV6 HSE. Sumatra Black/Ebony & Walnut + Dynamic Pack, + Cold Climate Pack + Memory Pack, Digital TV/DVD, Premium Leather, Cornering Lights, Cooler/Fridge Box, & most Options.

I think the BCM lives under the driver's seat too. 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed

Memory module under seat too.

Bcm by glovebox fuse box