The car 300D 1987:
troubleshooting the center lock system, I found the following:
The vacuum supply pump worked when tested using a direct line from the battery. The actuators worked and there is a voltage signal in the power input for the pump but not enough current to run it.
In the CD, they refer to connector X30, with terminal #1 feeding memory seats, anti-theft, and center lock pump/actuators. The memory works, the antitheft not and the supply pump not, actuators yes. Then the CD indicates a welded connector 48F located in "the right rear door sill" ??? (I do not know where) that distributes power between pump and actuators. The questions are:

1. is the anti-theft affecting the pump, or because the pump does not work it does not provide signal to the anti-theft and it stoped working until the pump fixed.

2. in the connector 30X terminal #1, if the memory works, does this mean the others also work, so I need not to check the X30 (it is in the driver's left pannel)

3. where is the rear door sill? could a welded connection provide power to door actuators (lower current) and not to the pump (corroded connection?)

4. what to do next?

Thanks for your help

any help?

I don't think we relaly have many vacum pump experts here. I've had trouble getting help with a similar issue with pump failure on my c220.

What is/is not the lock doing?

__________________
J.H.
'86 300E

Hi,
As I mentioned before, the pump tested OK. The problem is in the car wiring or something like that. There is a welded connection in "the right rear door sill" as the CD says, could somebody tell me where is that? inside the door? or where?
thanks

I found what could be the problem. I should have done a search on this connector earlier. It is "x48f".
thanks for the members of this site

I would look under the plastic door sill which is pressed onto the sheet metal seam with metal clips, if I remember. Or just inside the sill, under the carpet.
You should be able to pull the sill up, prying gently with a wide blade screw driver or putty knife.

__________________
DS
2010 CL550 - Heaven help me but it's beautiful
87 300D a labor of love
11 GLK 350 So far, so good
08 E350 4matic, Love it.
99 E320 too rusted, sold
87 260E Donated to Newgate School
www.Newgateschool.org - check it out.
12 Ford Escape, sold, forgotten
87 300D, sold, what a mistake
06 Passat 2.0T, PITA, sold

Las Vegas NV

I found the connection and fixed the problem. The sill area is under the feet of the rear right passenger, You need to move the front passenger seat (not the driver) as much as it goes. Then take of the sill metallec strip under the door (in the car not the door). You should be able to fold the carpet and follow the plastic cover of the wires. You need to pull the carpet as much as you can to allow for openning of the plastic cover. I had to take of the plastic base of the car pillar at that place to get more space (it has two screws and easy to take off). Once you open this plastic box, follow the wires from the pump and tear off the covering tape. You will find that connector, it is pastic transparent. In my case it was rusted to dust. I believe the welded surface suffered from condinsation and rusted badly. I advise all owners of 124 cars (older ones) to fix this conncetor (X48F) first if they have any problem with center lock system. The problem was that there is a misleading voltage indicating that everything is Ok but not enough power to run the system.
SEARCH the forums for "X48F" there are several threads, with pictures on where and how to fix. I added my comments here for further explanation
Thanks for the nice members of these forums