'05 W215 CL500 ECU fuse location?

[grober]

My favorite is always the main engine earth strap- cable itself or connections. Maybe take a look at the wiring under that carpet/ sound deadening - floor ,footwells ,kick panels , side trim etc for signs of water ingress/damp while you are at it?

 

[TimGow]

ah, yes, engine earth strap, I'll track that down.
I haven't seen where the ecu earth cables go to, I suppose underneath the fuse-box? The fuse body assembly does all come out, I've seen in forum threads. I can only imagine that there is an earth stud that has started to corrode. I hear what you're saying about the water ingress.

 

[grober]

ON THE PRINCIPLE that the W215 uses the same tech as the W220 this might be worth a look?

W220 S-Class Encyclopedia

w220.wiki

 

[TimGow]

Graeme, I like the encyclopaedia, such as this: DIY Voltage Drop Across Fuses - Quiescent Current or Parasitic Discharge Tests - W220 S-Class Encyclopedia

I have retested the ecu 'E' connector resistances to earth/ground. I found the ground stud on each of the inner wing strut towers; I cleaned both hoping for a fix, but no luck. I did use these proper grounds for the retest and now the pins 5-8 have resistance of 0.7Ω, that looks acceptable?

Back to what I know, it doesn't attempt to start and the scanners can't connect to the ECU via the OBD.
Is the ECU alive? Well fuse 78 has 12V, the connector 'E' of the ECU has 12V, but is the ECU up and running. To check this I took off the connector to the MAF sensor and turned the ignition on; probing the 5 sockets of the connector I got 0V, 0V, 0V, 1.78V, 0V. I was expecting a 12V feed to the MAF sensor, it needs power, not sure which technology hot-wire etc. but I believe that I should see a supply.
Is this a good indication that this ECU is not active when ignition is in run position?

Can a typical good independent Merc specialist test an ECU on the bench?
Does a W215 M113 ECU need to be programmed to the car VIN or are they freely interchangeable, i.e same P/N from a breakers?

 

[TimGow]

ECU pic attached

 

[grober]

I' m afraid I am running out of ideas myself now. You could try these guys for ECU testing?

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ONLY OTHER THING I can think of is a problem associated with ignition switch/security system not allowing the ECU to power up