Where is the K40?

[benzonline]

Where is the K40 relay in my 99 C230K? Pics would be good....because I want to open it up and check the for a bad solder as I heard it *might* be the cause for my loss in boost pressure or signal to the air flap valve.

thanks

[SLAMMED_C]

I dont have a pic.. but it should be in the right side (passenger) fuse box. its about 2-3" wide and 7-8" or so long.

[benzonline]

is the K40 in that black box against the windshield in the engine bay where the dealer plugs in the computer? Box is also has a sticker on it saying "battery in trunk"?

If so this box has to be removed or just opened?

[SLAMMED_C]

Originally posted by benzonline
is the K40 in that black box against the windshield in the engine bay where the dealer plugs in the computer? Box is also has a sticker on it saying "battery in trunk"?

If so this box has to be removed or just opened?

Yep.. its in there..
just remove the screws (4 I think) and then you can remove the cover and see the K40.

[benzonline]

thanks man!

[Proven Guilty]

i hate to ressurect an old thread, but i'm still troubleshooting issues with my supercharger. it doesn't engage 90% of the time, so i decided to pull everything apart and really get down to the grit.

i opened the panel as suggested where the stealership plugs in a STAR diagnostic, and didn't see any relays jumping out at me obvious.

There was a single black siemens relay, but when i google searched the part number, it came back as a fuel pump relay. i'm going to snap a quick pic with my cell phone's integrated camera.

here's a useful link for instructions on repair:
http://www.mercedesforum.com/archive/thread62400-1.html

[benzonline]

For me it ended up being a MAS sensor and not the K40. The car didnt have the usual MAS issues...it ran fine but at kickdown the supercharger didnt fire...it just acted like a normal asp C230.