ML270 CDI W163 coolant light on, how to solve?

I have a 2003 ML270 and have exactly the same symptoms as above i.e. had a loss of power and no kick down after being stuck in dead slow traffic coming round M25 Thursday night for about 20 odd miles, car went into limp mode so turned it off and back on big cloud of smoke (which cleared thankfully) and car was ok for about five more miles then went back into limp mode, the radiator light has come on and heated seats flash as per above, BUT the maxi fuse is ok 100% checked, is there another that operates this lot or any more clues?

I was suggested to do:
Star diagnostics can usually find the problem when in the hands of a competent individual....maybe you should seek one of the trusted SDconnect 4.

Finally I solved the problem
Is the control unit referred to the one on the top of the rad on the drivers side (left if you have head under bonnet).
Well I took it to a local but highly recommended SDconnect 4 and here is the list

code P1636 faulty boost pressure sensor
code P0100 mass air flow sensor signal voltage too low - faulty air flow metre
code P1403 EGR valve open circuit - faulty egr valve
code P1636 electric fan open circuit - requires fan unit and coolant bottle level sensor.

Now I have tried new fan so will not be changing that again, really believe that the coolant bottle/sensor will cure that one

anyway that's the list, I really want to buy all genuine parts.

Then when the site is on sale, I ordered these parts.
Expansion tank
and what I thought was EGR (turned out to be throttle jobbies so got refund on spot)
Oil filter & crush washer
Air filter

Merc main stealer
100 amp fuse for battery post £9.40  (indie who diagnostic blew it)

Saturday (yesterday) it was raining but my missus was not having any of it and sent me outside anyways as she said she would not put up with me whingeing about my broken motor and longer.

Fitted Expansion tank, fuse and the light was still on (not happy at this point) so thought ah well fit other bits anyway.

Fitted Maf and Map sensors found pipe down to turbo just pulled off, fitted air filter and put all back together properly and tightened up properly as I'm sure it will help.

Took EGR of and spent hour cleaning it (will do manifold another time but that will have to wait) and refitted all that proper.

So that's it time for road test thinking ah well at least it will be out of limp mode and I can take it somewhere, bite the bullet and get new fan motor etc.

Take it up road - NO DIFFERENT - right so now I'm wet got the hump and still no further, So I check every fuse, all good, the in the engine bay fuse box thought a hole in the back I spot some earths, now I also have a Honda Blackbird and they are known to have bad earths so I think 'got to be worth a try' had assumed indie checked al this in his 'extra hour to check connections and wiring' five little screws later and I've got cover off.

Found two relays that were just connected but laying in there
A fuse connecter again connected with two good fuses but again just laying in there ( by that I mean not clipped as if they were an after thought

And then slotted to the side was a fuse carrier that 'yes you've guessed it' had a blow 10 amp fuse in it, replaced fuse and radiator light went out, fan came on

Shut bonnet and took her down the road, be Jesus, she is now quicker than the star ship enterprise.

Now I'm not saying that it did not need any of the other bits as it certainly gets a shift on now but I am saying that the original fault was probably mainly that little 10 amp fuse that clearly had not even been looked at

Am popping in the indie's on way home tomorrow night to explain my dissatisfaction.