Door (Un)Lock With Aftermarket Alarm

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nvrau
C Class
Posts: 31
Joined: Sun 24 Jun, 2012 10:22 pm
Model you own: w168

Door (Un)Lock With Aftermarket Alarm

Post by nvrau » Mon 12 May, 2014 11:33 pm

I am researching how/where to connect an after-market alarm to the car's door (un)lock. It appears the lock & unlock signal is via the same wire using a 610 Ohm (or 630 Ohm depending on where I have read it). Some information suggests you can find the wire at the vacuum pump and others at the hazard/door lock switch in the dash.

I found a BLK/RED at the pump and occasionally it would work with negative & 610 Ohm negative. At the hazard/lock switch, I found the GRN/YEL wire controls the locks. However, I never did get the locks to (un)lock, at all.

Can anyone assist further?

nvrau
C Class
Posts: 31
Joined: Sun 24 Jun, 2012 10:22 pm
Model you own: w168

Re: Door (Un)Lock With Aftermarket Alarm

Post by nvrau » Tue 24 Jun, 2014 7:53 am

I have since confirmed the door (un)lock control wire (BLK/RED) to the pump is using CANBUS (See image of signal).

The wire (GRN/BLU) on the hazard/door (un)lock switch assembly is only using GND for both.

Now I am looking for an after market control module to interface with it. Everything I have found states they'are for 2003 and up, not 2002.
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scorchi0
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Model you own: w124
Location: Perth, WA

Re: Door (Un)Lock With Aftermarket Alarm

Post by scorchi0 » Tue 24 Jun, 2014 10:50 am

See attached wiring diagram. You'll need to print it to read it easily.

Also attached is a how-to for the diagrams, including a colour legend.

The pump is driven by the control unit (instrument cluster actually) but looks like it's not CAN since only one wire links the cluster to the pump.

Anyway, it's not necessary to muck about with that because the lock and unlock switches in the doors are simply switches to ground so will be easy to tap into with an aftermarket system.
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1991 S124 300TE - Smoke Silver
1993 C124 320CE - Brilliant Silver
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nvrau
C Class
Posts: 31
Joined: Sun 24 Jun, 2012 10:22 pm
Model you own: w168

Re: Door (Un)Lock With Aftermarket Alarm

Post by nvrau » Tue 24 Jun, 2014 12:10 pm

scorchi0 wrote:The pump is driven by the control unit (instrument cluster actually) but looks like it's not CAN since only one wire links the cluster to the pump.

Anyway, it's not necessary to muck about with that because the lock and unlock switches in the doors are simply switches to ground so will be easy to tap into with an aftermarket system.
HI scorchi, thank you for this!

Actually I already have those diagrams. When I checked the MOLEX plug on the back of my instrument cluster, there isn't a SN1 & SN2 with BLU and BLK wires, respectively. I know I could use the center dash (un)lock switch but it's only one wire and thus the potential to get reversed. e.g. Unlock the doors when I arm. Secondly, this wouldn't allow for priority unlock (Driver's door then all doors).

I see no way of interfacing without using the pump control wire. What kind of signal is going to the pump, if not CAN? It's certainly digital.

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scorchi0
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Model you own: w124
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Re: Door (Un)Lock With Aftermarket Alarm

Post by scorchi0 » Tue 24 Jun, 2014 12:46 pm

I will assume your aftermarket system has a switch to ground connection for lock and another for unlock.

These signals can be tapped on to the S86/1 door lock switch at the drivers door. This switch will be physically located at the keyhole, but the wires will run through the door jam and into the footwell somewhere. Connector X35/1 will be the connector at the door jam.

There should be a blue (bl) and a black (sw) wire on that door switch, though I'm not sure which is lock or unlock from the diagram. Grounding one of these will lock and grounding the other will unlock. Since your aftermarket system is providing those grounds, it should be easy to connect...

hope that helps.

edit: just re-read your post. The SN1 and SN2 are the terminal names. N is the name of the connector and it looks like it will be a two pin connector with the blue and black wires in it.
1991 S124 300TE - Smoke Silver
1993 C124 320CE - Brilliant Silver
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nvrau
C Class
Posts: 31
Joined: Sun 24 Jun, 2012 10:22 pm
Model you own: w168

Re: Door (Un)Lock With Aftermarket Alarm

Post by nvrau » Tue 24 Jun, 2014 4:37 pm

scorchi0 wrote:These signals can be tapped on to the S86/1 door lock switch at the drivers door.
This car uses all pneumatics. There are no wires connected to the door key mechanism nor is there a door lock switch on the door. When I turn the key on the driver's door handle, only the driver's door (un)locks, none of the others change. As well, the only button is the hazard/(un)lock switch assembly in the middle of the dash between the air vents.

The drawings you shared are the only one's I could find as well and it's for a 2001 with a wired system. This car is 2002 with all pneumatic locking. I tried using my VIN and my car does not come up.
scorchi0 wrote:edit: just re-read your post. The SN1 and SN2 are the terminal names. N is the name of the connector and it looks like it will be a two pin connector with the blue and black wires in it.
I should have used N1 & 2 as that is what I was referring to. Those two wires are not in the N connector; I disassembled it to make sure. I'm sure I can find something which would fit but I don't know if this will cause other problems or not. Even if it wouldn't, it doesn't allow for priority unlock.

I think I am going to take the pump apart and see if there is a way to add three wires to the control-board in it. I should be able to find a way to drive the valves without using the circuit.

Thanks again for helping!

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