Central Locking system problem

[kiato4]

Hey all:
The #12 fuse on my 16v keeps blowing. It controls the central locking system and the memory seats, and i think the alarm also. Basically, I replaced the fuse a few times, and it would work for a while, but after about 3 times of locking and unlocking the doors, when i go to lock it, only the door that i am locking locks and i have to do the rest by hand. I replaced the fuse twice after that and the same thing happened. How would I check for shorts in the system? On a side note, this started happening a week after I installed a sound system. Where would be a common place for a short near the rear seat area (which is where the wires for the sound system pass through)? Thanks very much.

[dad3258]

I have a s500 2000 mercedes the locks stop,working and I change the fuse twice but they blow out over night. could some one help me

[Mxfrank]

If you lift the bottom of the rear seat, you will find a foam box under the right side. The vacuum pump for the central locks is inside. If the short isn't there, it's still a good place to start your diagnostic checks.

[pwogaman]

On the earlier 124s one of the three command wires leading to the pneumatic pump splices mid-line to the alarm module, and the 30 circuit to the pump and other consumer elements. Those splices are under the carpet in the cable tray behind the front passenger. The splice are crimped with an aluminium sleeve. If a splice gets wet, as often happens and goes unnoticed under the carpet, the dissimilar copper wire and aluminium sleeve can corrode through the insulation and facilitate a sporadic short circuit.

Here are some pictures from my 1987 300TD which experienced this problem.





I hope this helps.

[puzzler]

I agree, the wiring tray that passes down the drivers side and also behind the driver seat..the carpet comes up by prying the door threshold strips up ..These splices in your excellent photos dont look oriignal mercedes to me..never see anything like this in mysystem.

I had a little mouse nest in the foam box of my vacuum pump case and they nibbled the wiring but caused no short circuits..But like you I found the wiring tray soaking wet and the cloth wrapping was rotted. 95 e320. Good to remove the stinky mush and dry out the tray..

[pwogaman]

They're original wires; even show up on the official diagram that way (e.g. X48F).

[puzzler]

X48F...Yes, I see. thanks. I dont find any crimp connecters like that..always plug in with pins. You are more expereinced..but I always see a little male/female push in connection..never a crimp with stripped ends which seems like a splice/repair..thanks for the good detail/photos and diagram..

[anziani]

After blowing a couple of fuses why do you keep trying? Obviously something is causing the fuses to blow. That's a good way to start a fire either in your car or your home.
Anziani
'97 Cl600 62K