Central locking, all windows, rear door latch and all other numerous CCU associated functions stopped working about a week ago ( I only have a key as the remote fob stopped working some time ago even after fitting with a new battery ). Ignition still worked ok and all other non CCU functions seemed to work, in essence car continued to drive fine but for the seemingly CCU related issues. After reading quite a lot here ( my thanks to everybody for their input, much appreciated ) about the CCU function and location I checked the fuses in the cabin fusebox and they all seem ok. I got a secondhand CCU from ebay (YWC000030 / YWC500211E) that was listed as being compatible with my TD4 2001 AWD I L314. My Haynes manual made it sound easy to replace the existing CCU but for a 72 year old laying upside down half in the footwell just to locate and remove the three bolts holding the fusebox mounting plate was a little challenging let alone disconnecting insitu the three plugs on the side of the CCU and finding and pressing the release tags in order to separate/unplug the CCU from the fusebox. So I was really pleased with myself when I finally managed to fit the replacement CCU and thought I won't refit the three mounting plate bolts just in case I have to put the old one back in again. Then it all goes pear shaped - after reconnecting the battery negative lead I put the ignition key in and turned to start the engine and heh presto no ignition, all display warning lights came on, horn going like it's trying to wake the dead. Is this indicating a) the ebay CCU is malfunctioning or it's the wrong part supplied b) I haven't refitted the two, smaller but seemingly the same, CCU side plugs in their right sockets or c) does the whole CCU/Fusebox assembly rely on the mounting fixing bolts to provide an earth connection. Any help would be much appreciated as I've had my TD4 since 2004 and it's been very reliable with only 125k on the clock so far.