Some strange goings on

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JohnCL63

Member
Joined
Mar 31, 2021
Messages
50
Location
Manchester
Car
CL63 AMG
The pre fuse box by the battery has a few fuses on the outside, however INSIDE it has a relay. Does anyone know what that relay controls?

Mercedes do NOT sell this relay separately however i managed to get one from a breakers as mine had gone.

Now the car is doing some strange things. Its been sat for a week.

I started it fine. Turned it off then it was comeatly dead. Even the hazards wouldnt work. Battery had voltage but it showed a big voltage drop at the pre fuse box.

Its now sat on trickle charge and its dead then its fine then its dead then its fine. When its running its fine. Its also sporadically just lighting up the dash even though the key isnt in it or near it!

Im confused as to what that relay actually does as this may shead some light on the situation
 
The pre fuse box by the battery has a few fuses on the outside, however INSIDE it has a relay. Does anyone know what that relay controls?

Mercedes do NOT sell this relay separately however i managed to get one from a breakers as mine had gone.

Now the car is doing some strange things. Its been sat for a week.

I started it fine. Turned it off then it was comeatly dead. Even the hazards wouldnt work. Battery had voltage but it showed a big voltage drop at the pre fuse box.

Its now sat on trickle charge and its dead then its fine then its dead then its fine. When its running its fine. Its also sporadically just lighting up the dash even though the key isnt in it or near it!

Im confused as to what that relay actually does as this may shead some light on the situation
Blimey John you're having some issues with this car! Sounds like you have a problem with a poor wiring connection somewhere or a bad earth. If you look at the website Fuse Box Info it will tell you what the fuse is. You must know a local auto electrician to sort it?
 
+1 for diagram sheet. Mine came folded up in the boot where the jack and wheel brace live. Not sure if yours will be in the same spot, but that’s where it is on a lot of Mercs.
 
Depends on model but pop the cover off the end of dash on the drivers side to reveal another fuse box and if you are lucky the printed legend will be folded neatly into it's designated holding place .

Mine was still there after 15 years !
 
Yeh, i do have the diagram but as this realy is INSIDE the pre fuse box and a "none changable" part, Mercedes dont even have it logged in their parts list, it doesnt tell you what it does!
 

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