It sounds like you have access to all the wiring diagrams so the files in the link below may be of no assistance but that would surprise me.
The files relate to the entertainment, Bluetooth, Nav and fibre optic systems in my 2005 LR3.
Dedicated to Discovery 3 and LR3, Discovery 4 and LR4 Owners and Enthusiasts. Totally free to join - message boards, galleries, off road events, social meetings.
www.disco3.co.uk
The info is a result of my successful removal of my dealer installed 0000 analogue bluetooth system and installation of the more modern 2121 fibre optic Bluetooth electronics.
What I found was the systems seemed to have multiple power sources rather than just a single power lead. It seemed the multiple power leads related to no key in the ignition, key in the ignition but off, key in accessory position and key with engine running scenarios. I know that this is not being helpful but that was my determination; also I think that means more than one fuse, wherever they might be or a RR. For me, the fuses were located on the fuse box behind the lower glove box on the passenger side.
Since you want to eliminate some component, probably the best bet is to remove the electrical connectors to the unit and see what else dies as well - and that is the problem even with removing fuses.
Below you do that however, I suggest to try what is called a
Hard Reset per the instructions below. I have had good luck with the procedure getting a locked up radio etc working again. For me, this often happens as a result of replacing the starting battery or perhaps even disconnecting it. The good news is that the Hard Reset procedure either fixed the problem or at least did no harm to anything and did not cost anything to try either. Also it is a standing up clean hands procedure, no aerobatics required sort of fix - rare on a Land Rover. For special tools, per below, all you need is a foot long length of 16 gauge electrical wire.
Hard Reset Instructions
In brief, to start the hard-reset process, open the hood but close all doors and let your vehicle go to sleep - no radio display etc and no key in the ignition. This will take a couple of minutes and do not open any doors until the reset is completed. (I find that it is often a good idea to have the driver’s door window rolled down and the key in one’s pocket whenever fooling about the vehicle.)
Also, when I play with a car battery, I remove any rings I have from my fingers, also my watch.
Have the car keys in your pocket.
Disconnect the ground battery terminal from the main starting battery.
Disconnect the positive battery terminal from the main starting battery.
The reason for this order is if a wrench or loose battery cable ends grounds to the body, no arcing or other bad things happen.
(I assume that you only have one battery in your vehicle. If not, disconnect the others as well and leave them disconnected until after all is done.) I have the Traxide dual battery system installed in my 3.
Connect the negative cable end to the positive cable end. (
NOT to the battery.) To do this, you will need a short length, (a foot or so), of light gauge, (14 to 18 gauge AWG, insulated stranded copper), wire to span between the battery
cable ends as there is not enough slack in the positive and negative battery cables for the ends to be able to touch each other.
Hold all together for about a minute or more, (suggest at least two minutes), as you are discharging memory modules within the engine computer and elsewhere. Then it is suggested you then just let all sit disconnected for say ten minutes, (minimum five minutes), prior to commencing to put the battery cable ends back on the battery posts per the following order.
Reattach positive terminal to the main starting battery positive post.
Reattach negative terminal to the main starting battery negative post.
Start engine and hopefully none or at least fewer warning lights and the radio when turned on plays music rather than being silent.
Reset time on the radio - note that the station presets are still there as not everything is erased. Nothing much else needs resetting either.
You can also now connect up the other batteries if you have a multiple battery setup.
This is a link to a thread in disco3 re the hard reset procedure.
http://bit.ly/14WXXR1
http://www.disco3.co.uk/forum/topic19547.html
This is a link to a thread on Disco3Club re the hard reset procedure.
http://www.disco3club.co.uk/phpbb/viewtopic.php?f=67&t=3374