From 2005, the entire infotainment system in the L322 uses the later MOST (Media Oriented System Transport) Fibre optic bus. Same as on Disco 3 and Range Rover sports. In fact exactly the same ECU's programmed with exactly the same software.
It is quite advanced and can scare those never having worked with it much, and diagnosing problems with it requires a somewhat different approach to normal.
It's basically a loop that goes in and out of all the Infotainment ECU's.
Each ECU gets the light from the preceeding one on its input and then re emits it on its output. If there is a break in the loop or one ECU looses power or stops working for any reason, the whole bus goes down.
When that happens you get the common symptoms you describe.
Here is a picture of part of the MOST Bus loom
[/IMG]
I recently fixed a 2005 L322 with the MOST Bus down, turns out the telephone module had water ingress and was not repeating the light.
I fitted a new one, but later cleaned the old one up and got it working again and actually retro fitted it in my own Disco 3.
If you unplug the MOST connector from an ECU, you should see light at the end of the input terminal of the cable, They are arrowed for direction. For a split second you might also see light being emmitted from the MOST connector of the ECU. Also if you hover the connector over the socket close enough, sufficient light will reach the ECU's reciever for it to fire up its emmitter.
If you dont see light in the cable, the problem is before that, if you dont get light out of the ECU then its that ECU that is not working as it should and you need to check its power feeds fuses etc.
There is an LR tool availiable called a MOST Prism to aid in MOST bus testing, its basically a socket with a loop of cable to by pass each ECU in turn.
[/IMG]
Hope this helps.
Hi, I'm new to this and indeed distraught.
