Wednesday, June 11, 2014

Keyless entry replacement on the W124

My wireless entry failed recently due to the siren wiring short circuiting and thus I am no longer able to use my remote to unlock or lock the doors.

Not too much of a problem as I'd always wanted to replace the system as the range of the old one was quite limited.

I had bought a keyless entry system from Aliexpress since 2 years ago and had no good reason to install it until a week ago when it rained so heavily that it shorted my siren +12V wire to ground and rendered the old keyless entry system useless.

This was the system that was purchased and the instruction manual looks like this.

Honestly, even for an electrical engineer, the instructions were quite useless...

Then I found help,at Peachparts forums, where many classic Mercedes owners, contribute technically to helping other owners, in this thread.

They were using the same system and one of them had the proper wiring instructions.

The wiring colour code was exactly the same on my module [ Left side ].
The only problem now was to look for the corresponding signal wires to tap on the car itself
[ie door lock/unlock, blinker ]

Lucky for me, my old keyless entry system, had the required wiring already brought to the front [ under dashboard ] where the door, turn signal blinker and siren wiring, was already on the connector of the old keyless module. And because I had the instructions and wiring diagrams for the old system [ handed over by previous owner ], all I needed to do was to snip the required wires from the old connectors and connected them to my new module wiring.