I'm planning to install a keyless entry system on my W123 300D this summer. This should not be too difficult of a project. My thoughts are:

1.) Since pretty much all keyless entry systems activate the locks electrically, I need something that will (by remote control) physically move the driver door lock knob upward.

2.) Relays to flash the headlights upon lock/unlock won't be too hard to install and I can do it easily.

When the project is finished, I'll be sure to post pictures and detailed instructions. Tell me your thoughts/opinions, and thanks for your support!

I'm assuming you have vacuum door locks (I can't remember...). If so, look up my thread on keyless entry installation for under $100.

yes they are vacuum controlled.

It sound interesting. I will be looking forward to the pics, etc.

just bought a 123 with a non op keyless entry system and interested how this ever turned out and how you did it. I am looking for tips on what might be wrong with my setup

Do I get points for reviving a 12 year old thread? :D

I put on my old 124, a keyless entry module I bought from a guy in Australia.

The unit installed in the trunk and it activated he trunk lock. This automatically activated the other doors. It took 20 mins to install, worked great.

Hey I found it:

Home - Mercedes Benz Plug-In Keyless Entry Upgrade

Not sure about the W123 though...

Wow. I haven't been on this forum in years. But the email notification came thru!

Yes, but they get erased into the negative because you are in the gasser forum. You heathen!

can't help but post this

http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

and

http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/343527-fs-w126-chasis-keyless-remote-%2450-shipped.html

I have been using Keyless on my 83 W123 for 6 years. You should see an actuator if you open up the driver door panel. It is used to switch the vacuum switch between the lock and unlock line. The configuration is same as a normal positive trigger to lock and unlock. It would NOT be configured as pneumatic control. Have fun to repair it.

I've had keyless entry for years on my cars. I just seldom lock them. Living in an area with low property crime, driving beaters, and never leaving anything of value in view help a lot.