Hi! I have read a bunch of threads about installing (china) remote for the w124 door locks. I have done it on a few w124s myself earlier.

Today I was going to install it to my 1989 230 coupe. Both doors and trunk lock and unlock with the key. I followed the schematics and double checked the wire colors. I spliced into the green wire from the passenger door, and here is the funny part. First time I clicked the button on the remote, the doors locked. But after that nothing happened. Then I realized that the passenger door won't lock/nlock the other doors with the key anymore even after having removed the remote module again. The other door and the trunk still works.

The green wire stills gives 12v when the door is unlocked, and 0v when the door is locked (or is it the other way around?) and it still lock/unlocks from the other door and the trunk. It seems the remote module killed the "green part" of the pump, if that is possible?.

Have anyone else encountered this? Is there a fuse inside the pump? I was about to open it, but I will wait to see if I can find a replacement first.

Feed back is greatly appreciated!

To start answering my own question. I found a pump from my long gone 1994 E250d. It threw me off for a little while because it had a 6-way vacuum connector fitted.

But the connector came off easy enough and then the pump was a direct swap for my 1989 230ce. Who would have thought! And voila- all locks lock all locks again!

Having a working pump in the car allows me to play around with the old one. The lid comes off easy too, and reveals a small circuit board with just a handful of components. No fuse.

I almost can’t believe this is not working on one of the circuits. Don't have a meter here. Will report back later!