Late-124 Keyless Entry
 

Keyless entry ("KE") to my 1995 E300 is finally complete. This is not so much a "DIY" as it is a "here's what I did." I can provide more details if anyone wants them. Specifically designed for model year 1990-95 W124s (those with the "convenience relay" under the rear seat), pieces of this thing can be used on any 124 and probably other M-Bs as well. YMMV as usual.

This is a complete system -- it may do more than you want. Features:

• All key-operated functions are duplicated with the remote. Key and remote can be used interchangeably. The "KE" electronics occasionally gets lost if you mix/match but re-sync is easy by pressing the opposite button.

• Central Locking is also available from a console-mounted switch, which duplicates the function of the door buttons. (This console switch, like the door buttons, does not arm the alarm.)

• "Convenience" closing of all windows and sunroof is available with the KE remote; its use is the same as it is with a key. This is a complicated system with a long list of what it will or won't do and I still haven't figured it all out.

• A security switch disconnects the driver's door from Central Locking. This allows the driver to lock or unlock his door with the key or with the door button without locking or unlocking any of the other doors. Complete locking/unlocking is still available with the console switch or with the remote.

Wiring diagram:

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Electronic bits, under the rear seat next to the Central Locking pump. When this picture was taken I hadn't run the wires under the carpet to the switches in the console. This under-seat location makes it easy to connect to the "Convenience Unit," on the other side of the seat, and through it to the alarm.

http://i323.photobucket.com/albums/n...lete_40823.jpg



KE remote and the added console switches. The Central Locking switch is a window switch with the up/down arrows blacked out -- alas, the factory switch doesn't have the right pin-outs for my circuit. My car's console has the optional "limo wood" panel (124 683 38 37) with all of the switch holes punched.

http://i323.photobucket.com/albums/n...le_40837-1.jpg



Details? Just ask!

Jeremy

Where's the love people? This is an awesome upgrade!

Bless you, my child.

Jeremy
When you say late 124 what years are you refering to? Sounds like a neat project if it will work in my cars. Don

First paragraph, 4th sentence: "Specifically designed for model year 1990-95 W124s . . ."

Thanks Jeremy i dont know how i missed that must be getting tired. Don

This is great, I need to sort out the auto close feature on my car, I think I may need your assistance in it.

Car has an aftermarket alarm stuffed into the dash knee panel, which has two relays and works the central lock pump, It only works when the key is at point 0. This does not "arm the alarm" . The door lock button also works the pump like it should. If I lock the trunk lid the alarm does arm itself like it should.

The auto roll up feature does not work though, which i believe has to do with the arm feature or the remote system buggering it up.

Excellent work. This is on my to-do list for the 300D. I like the integration with the convenience relay.

Options . . .
 

Since you have the identical car I may be able to help. The window-close feature is triggered (in an unmodified car) by the switches in the door; as these are also the switches that arm the alarm, it's possible that the installer of your aftermarket alarm cut some of the wires and connected them to his alarm.

You have to decide whether you are willing to live with the consequences of the aftermarket alarm or bite the bullet and attempt to return the wiring to a stock configuration. It's always risky making assumptions about where the wires go based on a schematic wiring diagram; too often the artists are more concerned about making the wires look pretty on paper than accurately describing what's actually in the car. With that caveat, the wires from the driver's door could run first to the alarm and then to the convenience relay or vice-versa. Either way, those wires are interconnected. Without them, the auto-close feature will not work from the driver's door.

This brings up an option: use the wiring from the passenger door and abandon the mess in the knee panel. Question for you: does auto-close work from the passenger door lock? It should, it does on my car. If it does, you have unboogered wire to work with; if not, there is a larger problem. NOTE: auto-close does not work from the trunk. I just went and confirmed that.

Jeremy

Here is a question, how does the auto-close/auto-open know when the windows is fully up/down? Is there some kind of limit switch? Current sensing?

Answer
 

An excellent question. The "auto-close" term is really a misnomer. It is really "auto close as long as you keep the key turned (remote button pressed)." Thus, YOU are the limit switch. The convenience relay does not know when the window (sunroof) is closed.

This brings up a question I had not considered: how does the convenience relay know when the window is fully open when you press a front window switch all the way to "auto down?" I'll have to look at the diagrams because I don't know how that works.

Thanks for asking!

Jeremy

Interesting. I've often wanted to incorporate this feature set into one of my 126/124s cars but not knowing when to stop makes it difficult. I mean, you could use limit switches for auto up/down... That would be annoying, installing/mounting/wiring 8 switches in the doors. Current sense/limit would work better/easier. Current draw should increase when the window hits the top/bottom, soon as that current spikes up cut power.

It works on the same concept as auto antenna. The electronic cuts off on current spike when the window reaches the limit of travel.

Stop!
 

Good, thank you. I wondered how that worked. The circuitry must be part of the "convenience module." Certainly the regular power window hardware doesn't have anything like that, at least not in any Benz I've ever owned.

Jeremy

You could insert a DEI530T module in-line with the window motor. Acutally one module accommodates two windows. You'd get a pair of DEI530T's to cover the whole car.

This module provides end-of-travel / obstruction cut-out, but it's primary purpose is to provide "one touch" up/down window operation from the interior window switch.

You'll also find it has logic inputs that, when grounded, can make the attached windows go up or down.

It's easy to attach this to a timed remote button press, joined with lock or unlock.

And if you want to program special features using a microcontroller, you'd end up with something like the products on autowindow.com