'05 W215 CL500 ECU fuse location?

[TimGow]

Hello,
I'm looking for the fuse and relay for the ECU.
Online fuse sites say F29, F30, F43, F44, F78, F87, F88 and relay K.
Fuse 78 and Relay K are said to be in the Auxiliary fuse/relay box. Can you point me towards this Aux box at the front of the engine bay?
Is this info correct for '05 CL500?
All help much appreciated

 

[grober]

Fuse Box Diagram Mercedes-Benz CL-Class/S-Class 1999-2006

Fuse box diagram (location and assignment of electrical fuses and relays) for Mercedes-Benz CL-Class (CL500, CL600, CL55, CL63, CL65) / S-Class (S280, S320, S350, S400, S430, S500, S600, S55, S65) (C215/W220; 1999-2006).

fuse-box.info

 

[TimGow]

grober,
Thank you for the link; this site doesn't show where the Auxiliary Fuse box is located in the car, there is no photo showing it in the car. I don't see it in my car, do you know where this box should be?

 

[grober]

FUSEBOXNO2
FUSE30 AND RELAY K [ SEE FUSE FUNCTION]no mention of F78?

 

[grober]

FUSE78 is at the end of the dash

W215 fuse & relay chart

www.benzworld.org

 

[TimGow]

Hi Graeme,
Thank you, found F78 at end of dash, that one's ok.
I'm also looking for the Motronic fuse and relay, as in pic below. I'm not sure whether an M113 CL500 has Motronic but it's listed on the fusebox.info (and my ecu appears to not be live).

 

[grober]

Hi Graeme,
Thank you, found F78 at end of dash, that one's ok.
I'm also looking for the Motronic fuse and relay, as in pic below. I'm not sure whether an M113 CL500 has Motronic but it's listed on the fusebox.info (and my ecu appears to not be live).
View attachment 117563

Can you post a link to where you got that diagram/list?- it may refer to an earlier model?
most 05 cars will have a small prefuse unit with fuseable links--don't know where that is on your car its not listed---- you also have to be carefull about differences in any description from RHD/LHD position. Remember also hat your ECU needs a good earth connection/s to function correctly.

2004 W215 CL500 Obd Fuse Location | Electronics and Audio

Hi All, Can anyone tell me the location of the OBD diagnostic socket fuse on my 2004 CL500. Thanks

forums.mbclub.co.uk

 

[TimGow]

Hi Graeme,
That auxiliary fuse box is shown at the bottom of the page: Fuse Box Diagram Mercedes-Benz CL-Class/S-Class 1999-2006
I will check the earth connections, when I work out where they are, thank you.
Really, no matter where the fuse and relays are, I need to also check the supply to the ecu. I have subscribed to Haynes for their new online info. Do these references look ok below? F3-78 could be fuse 78 in the end of the dash fuse box?
Tim

 

[grober]

Mercedes use certain power circuit designations e.g. circuit 30 is permanently live ------ circuit 15 is live on ignition looking at your last diagram maybe there's problem with circuit 15- see that other link i posted
W215 fuse & relay chart the CL600 series of pdfs

 

[grober]

v

 

[TimGow]

Graeme, thank you for that pic, is that from a MB workshop manual? That's it fuses 87-91. In the fusebox.info it says location at front of car, your doc says engine compartment front wall; this looks like the bulkhead/firewall. Now off to have another look.

 

[grober]

and try this for tthe prefuse unit

W215 hidden fuses revealed

www.benzworld.org

 

[TimGow]

I don't see that fusebox for fuses 87-91. I was hoping that it was near the ecu & the right hand fusebox.

If I have identified the ecu correctly, it has several wiring connectors; do you have a diagram showing E1, E2, E22 etc. or on a photo? I don't yet understand how to identify terminal E3.

 

[grober]

have you just checked fuse continuity or [to take one example] is fuse 78 or any of that end of dash fuse block getting power on ignition switch on?

 

[TimGow]

I started with checking fuse continuity and have now turned to checking voltage. Fuse 78 has power, now I'm a bit lacking how to navigate the trail. If it were an earlier efi car with a throttle cable, I would check the TPS for 5V to indicate that the ecu was live but not so sure here. The ecu has 2 long mutli-pin connectors, and a small connector in-between? I could pull the connectors and look for 12V? I would dearly like to see a full circuit diagram so that I can be methodical.

 

[TimGow]

I may have mistaken the ecu for it's neighbour, it has 5 connector sockets, similar to this post?
ECU Pinout - MBWorld.org Forums (SL500 shown not my CL500)

 

[TimGow]

Is the ecu for '05 W215 with M113 of type ME 2.8?
If so then I've found this pinout document - ME 2.8 ECU Pinout - MBWorld.org Forums
On this basis, checking 'E3' for power supply (Haynes online diagram above) makes some sense. Also, checking those ground resistances £5/6/7/8.

 

[grober]

W215 hidden fuses revealed

www.benzworld.org

Have you had a look at the above thread--one of the pdfs has some usefull pictures of prefuse connections locations to check-- these prefuse units are fundamental to the function of the various fuse blocks by acting as primary power supplies.
You haven't said anything about the history of this failure- was the car running normally and then stopped or has it sat dead for a while-been flooded etc any symptoms pre failure. Much as I hate to say it with these complex electronic systems sometimes you need to use the Mercedes Star system to home in to the area at fault

 

[grober]

When I say flooded that generation of CLS are prone to body leaks and most of the wiring [ including the fuseable links] runs under the carpets /sound deadening on the floor and can hide wiring/connection corrosion

 

[TimGow]

Graeme, thank you for your support. much appreciated.
The back story is that the LH rear ABC strut began to leak so I stopped driving her while I located the suspension parts. The battery drained down low within a couple of weeks of standing, but after the battery was charged, the car wouldn't start, nothing happens when key turned to the start position and the radiator roars flat out. Another issue is the SRS error and the iCarSoft MB v2.0 scanner says that there is a short in the seat.

I've pulled the E plug out of ECU and measured the voltages. The battery voltage was 11.95V as it's drained a bit, back on charge now (must fix this issue also). The fan is roaring when I take these measurments with the key in the run position.
1 11.13V
2 11.12V
3 11.13V
4 11.10V
5 0
6 0
7 0
8 0
9 6.87V

I then checked the resistance of pins 5, 6, 7 & 8 to earth/ground. The resistance kept climbing as I checked and rechecked, rising to 20, 30, 40Ω etc..
5 10.0 Ω
6 5.0 Ω
7 11.0 Ω
8 17.0 Ω

This looks like a bad earth to me... Now maybe I should recheck the resistance back to the battery; what I did was connect one lead crocodile to a bolt head on the front panel above the radiator.