Parking sensor- where does the wiring originate? Circuit?

[elite_504]

Hi folks,
I'm still very new to the fold.
My new-to-me C32 Estate is fitted with parking sensors F+R, but it doesn't function. I understand if there is a fault with it that it show red bars. Mine shows nothing at all and is dead as a doornail. I suspect it is either disconnected, or a fuse has gone, but even consulting the wiring diagrams, I can't see where it's plugged in. Any suggestions from anyone? Any good hints to start fault finding?
All info appreciated.

 

[richard]

It gets its power from the Rear SAM (which is part of the rear fusebox on the left in the boot)

Fusemap is probably in with the fusebox at the end of the dashboard (under the cover which is obscured when the door is shut)

But looking at SAM wiring diagram, it looks like it goes to F13 which is a 5A fuse, which is fed by relay F

Fuse 1 and relay A are at the bottom of the fusebox , so yours are near the top

The plug plugs in the back of the fusebox, they are all keyed (its plug 12) so cant go in the wrong hole if its fallen out

Richard

 

[elite_504]

Great stuff man, thanks so much. I'll check it all out and report back!!

 

[elite_504]

Woo hoo, you are the man!5a fuse 13 replaced and indeed the system came to life. The fuse was missing. The system was showing something consistently in front of the front right of the car. I guess this drove the previous driver nuts, or he just wanted to cover the system fault when I bought the car by pulling the fuse. Looking at the sensors, they had been painted over and the pain was cracking. Paint carefully scraped off with a sharp scraper, and the system is all 100% now and working as it should!!

Thanks so much for the info.

I also checked the Mrec fusebox diagram from the instrument panel as reccomended, and I guess mine is an early build standard, so it didn't list the parking sensors on the diagram at all.
Whilst checking though, I see fuses 5, 6, 7 and 16 are also missing, along with relay D. Any idea what these components are meant to be?? My Merc fuse diagram says Telephone and Language control (I guessed language control was something to do with COMAND and would be fused as such, but seemingly not. Any ideas? I was tempted to just replace the 4 missing fuses and see what happens, but not wanting to se light to my vehicle, I thought perhaps not. . .

 

[richard]

Dont put fuses in you dont need

And remember that the circuit diagrams are not always right and change over time too, so the one i'm looking at may not quite match the car.

F5 feeds relay C, which feeds the AMG charge air cooler motor M44
F6 not used, feeds connector 28 pin 1 on the back of the fusebox
F7 cant find in the diagrams I have
F16 VCS (linguatronic) - which is an optional system that controls phone and COMAND
Relay D Neckpro on cars after 06/05

The only one that seems slightly strange to be missing is F5 .. my temptaton would be refer to the fusechart to find out what size it should be, put one in and see what happens (does the car drive better) and if not, remove it.

R

 

[elite_504]

Hmm, indeed, sounds like that fuse should be there- I shall investigate further. She certainly seems to be driving ok, BUT, she hasn't been on the dyno, and if I'm 50 horsepower down I wouldn't necessarily know. I'll check it out and report back. . .