Serpentine diagram 2004 mercedes c240 - 1994 Buick LeSabre

Here you go:

https://www.autogenius.info/mercedes-c-class-c240-fuse-box-diagram/

You tube video Mercedes Benz 2003-2005 C230 M271 - Serpentine Belt Replacement (Detailed)
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for serpentine belt R&R :
https://www.youtube.com/watch?v=X5U2wS9uSvE
for timing belt R&R
https://www.youtube.com/watch?v=MGUXyohaOJc
thats the best i can do , I am in to Japanese tech sorry .

it is integral to the transmission , i've put a link to a video , shows the basic procedure so you will know if it's something you could do or get a mechanic
Mercedes Benz Transmission Control Module Replacement

Hope this helps

CS = crankshaft pulley

For left-hand drive (LHD) vehicles the fuse box is placed on the left side of dash board, (driver's door open), behind a plastic cover. On the inner face of the plastic cover you will find the fuse box diagram.
Also another fuse box / relay plate is placed under bonnet in engine compartment area.

My sincere apologies for the delayed response.
I am personally going back to answer your unanswered questions.

I do not know if you still need this information, but I am going ahead and answering it anyway. You may want to Print the Diagrams for future use.

CLICK on the following LINK. It has the Belt Diagrams you will need.
I do not know if you have the C230 or the C240 Model. However I have included both Links below.

If you would: Before Clicking: Let me know if this helped you, or if you have any additional information or questions. Feel Free to contact me at FixYa.com!
Again my apologies...
Thanks!
For the C230:
http://www.2carpros.com/car_repair_information/year/2002/make/mercedes-benz/model/c230/2002_mercedes-benz_c230_drive_belt_routing_diagram.htm
For the C240:
http://www.2carpros.com/car_repair_information/year/2002/make/mercedes-benz/model/c240/2002_mercedes-benz_c240_drive_belt_routing_diagram.htm

put a ratchet on the tensioner and pull away from the belt.

Hi, You need to replace the alarm siren. It is also a module. It is located in the right front fender well. The reason they go bad is because they are located in a place where they get wet.