12 volt while driving.

Usually a fused relay up front that switches when engine is running to supply +12 volts to fridge.
Need to establish if fridge is getting voltage when running, also checking that enough current is available too.... if so then you have a fridge problem. It's more than likely a supply problem, worth checking the relay and fuse first at any rate.

Did you try it manually on 12v when engine running

Hi Colin, saw your post this morning and would like to offer my opinion, for what it's worth, although I have not been part of this thread previously.
I am assuming your unit is a "CBE-DS-520" which is the distribution/consumer unit which supplies the various 12 volt circuits in your motorhome. Depending on the model, there are a number of different types as they are customised by the motorhome manufacturers to their individual specifications, the fuse for the fridge tends to move position. However, it is mostly in position 6 and is a 30 amp fuse.
I would suggest that you check here first making sure that the fuse holder is OK as a lot of heat can be generated by the load from the fridge. This can cause the fuse holder to lose tensile strength and result in a bad connection and cause the fridge to operate intermittently
If all is OK here then check for 12 volt supply, at the fridge, when engine running. If there is no supply voltage then things are now going to become a little more involved. i.e. you will now need to dig deeper into the DS unit and check the internal connections. If you have your motorhome from new you should have a schematic wiring diagram for your 12 volt system.
There are a number of plugs/sockets inside the unit and, from memory, the + (positive supply) for the fridge comes through plug number 22 which is coloured RED. The fridge supply will be on pin 2 or 3. The plug has a RIDGE on one corner and if you look at it with that ridge at top left, then pin 1 is the top left corner with 2 and 3 vertically below.
Plug number 27 which is white, and is the largest plug there (12 connections) carries all the negative connections. It would be a good idea to disconnect both of these plugs, 22 and 27, and check the pins, in both plug and socket, for signs of overheating.
That should be enough for you to check, for the moment, and hopefully you will find the problem. Otherwise, it gets a little more complicated from here. Come back if you don't get it sorted.

As i stated previously, these units are customised for the various motorhome manufacturers who use them and some of them do have a Charge/Fridge relay mounted on the PCB. This relay can be replaced if one can get hold of one. What you are saying is that, not only is your AES fridge not working, but your habitation battery is not charging either?? What you need to check is do you have the required ignition input on plug 25 pin 2. This is a small 2 pin plug, red colour, just above the +B1 terminal. You should have, minimum, 13 volts here when the engine is running. This triggers the change-over circuit but is voltage dependent. If you have the correct voltage here it is possible that you have a component failure which might mean replacing the DS unit, and that means, unfortunately, going back to the motorhome manufacturer.
Alternatively, a good electronics engineer should be able to sort it. Probably cost less too.
Something else that you might check is the 'AES Link', this is just to the left of plug 22, the red 9 pin plug I mentioned in my previous post. If this is broken or loose it would stop the fridge from working but I don't think it would stop the battery from charging.

Sounds like you had a little bit of a struggle with that one Eamonn. However, you got there in the end. Motorhome/Caravan fridges can be troublesome when running on 12 volt as the components, such as fuse holders, plugs and sockets etc., are not really up to carrying the loads and can, and do, fail. Always check your wiring connections/joints first before taking everything else apart.
Your Electroblock was manufactured by Schaudt, in Germany, and they are a great company to deal with if you need assistance. Unlike CBE in Italy, they will deal direct with the public and even offer a repair service for these EBL units. You can also download manuals and diagrams from their website. If you can't find your specific unit listed then just E-mail them and they will send the information to you.
Happy motorhoming!!

Great news Baguette!
I hardly think there would be an intermittent problem with the "Battery Separator" relay, from my experience, if the coil fails that's the end of it. An intermittent fault is more likely to be at a 'connection', such as plug 25 or somewhere else on that (D+) signal. There should be a fuse on that line, external to the DS unit, rated around 3Amp. Don't ask me where it's located as it could be anywhere but, logically, it should be in the vicinity of the DS unit. If you can find it check the security of the connections.
Some further, trivial, information. The "Battery Separator" relay, when energised by D+, energises a second relay, which could be referred to as a "Split Charge" relay which you referred to in a previous post. This second relay then supplies the power for the fridge and any of the other items that will work when the engine is running. In my first reply I referred to plug 22 and pins 2 and 3, these are both intended to supply a fridge, one is for a 'Three Way' fridge and is switched through a relay, where the other is for a 'AES' fridge and is fed directly from the second "Split Charge" relay mentioned above. For the life of me i can't remember which is which, but I don't think it's important now.
Incidentally, I based all of my information on the assumption that your unit is a DS-520-RA, so I hope that I got that right.

I am not sure if the fuse you refer to, No. 15, is protecting the incoming D+ feed. However, you could check by unplugging this fuse and then checking to see if the Fridge still works with engine running.
If there is a problem looming on the PCB it would, more than likely, be contacts in the "Split Charge" relay, as that is where the biggest load is carried. The relay can be replaced, if you can get hold of an exact match as it is mounted on the PCB and the soldered connections would need to be in the correct alignment and configuration.
However, it would be possible to mount a relay externally and pick up the relevant connections within the DS unit.
I really feel that your problem is/was just down to poor connections created through years of use and vibrations generated through driving.
Keep the Faith!!

Donal