Alarminstallation

[W124-300D]

I would very much like to know about the wiring in my merc. It´s a 300D Automatic -91.
I intend to install an alarm in the car and would like to know a few things.

Is it possible to do the wiring an easy way? Or am I supposed to throw out the interior before accessing the right places?

Is there by any chanse some kind of installationguide for caralarms for W124 models?

 

[bigasotonuk]

Hi,
Doesn,t sound as if your to sure of your ability in wiring the alarm up i would get a auto electrician to do this they will also be able to certify the installation which you would need if you wanted insurance discount.
Saying that, i have fitted alarms and you should be able to acess all areas needed to install the alarm by removing the lower dash trims on the drivers and passenger side and the steering column shroud, drivers door panel (possibly) with access to under the bonnet too, but it will depend on the facilities you want the alarm to have.
Installing an alarm on this vehicle "should,nt be" any differnt than any other car of similar age.
what sort/make of alarm do you want fitted? what do you want the alarm to do remote locking full closure etc.?

 

[Bolide]

You'd be better off fitting an immobiliser and/or a Tracker than an alarm

Nick Froome
www.w124.co.uk

 

[W124-300D]

The alarm is an Avital 2300.
I chose it because all the locks doesn´t work properly and I was considering some kind of remote.
I would like the remote to operate the locks, the heater (Webasto with clock) and the alarm, of course.
To my knowledge this system is equiped with an immobiliser, and a few extra channels wich I might use later.

 

[bigasotonuk]

I take it you have the installation instructions for this alarm
Do you mean your cars central locking is not working? if so i suggest you fix this first as the alarm remote locking only triggers the central locking does,nt repair it or replace it
Heater not sure what you mean but i suggest you use one the spare channels on the alarm in conjunction with a relay.

 

[bigasotonuk]

done a search on net and found avital well nice alarm.
It said that you have to have it fitted by accreditted installer as they won,t register the alarm for any sort of warrenty just thought that i ought to tell you
http://www.avital.com/guides/ogs/avital2300_owners.pdf

 

[W124-300D]

It seems one of the locks is stuck some how. The central locking works just fine.
As I mentioned, I was looking for a new lock or a remote system. And I stumbled over an alarm with wich I porbably can operate other functions as well.
Of course I will have the wiring validated for warranty.
But before that it would be nice to be able to install everything in a proper manner, so it both looks good and functions the way it is supposed to.

 

[bigasotonuk]

Part of the conditions of the alarm installation is that it is to be done by a approved installer which will include the way the various control units positioned, fixed and mounted to the car the way the cables are routed and hidden within the vehicle the position of the l.e.d. also there are several ways the immobiliser can be wired to the vehicle also specific points in the vehicles to take supplies and switch wires, you,ll need this information if you want the instal certified.
Brutally honest with you i think you would have a hard job to find any auto electrical company to certify an install that they did,nt do (i know i would,nt).
Use a reputable alarm installer and you will get a decent job.
I,ve seen quite a few alarm installs of decent thatcham approved alarms and equivalent "all" have been good quality because of the standards needed to become "approved" alarm installers. My opinion is based on the fact i,ve fitted electrical systems to and maintained electrical equipment on U.S. and British military vehicles.

 

[W124-300D]

All right!
A few new questions:
Behind the ignition there is a red cable for 12V all the time, the starting current comes from a pink/yellow cable and the starter is behind the violet cable?
Behind the hazard there are two positive cables for the blinkers wich are black/white (left) and black/green (right)?
But for the central locking there has to be some modifications. I wonder what colour the cable that steers the vacuum pump has? And can I also find a red cable for 12V nearby?
Are the door switches accessible from the headlightswitch or should I go for the other lightswitches(brown/grey)?

 

[bigasotonuk]

Do you have a multimeter (continuity tester/volt meter)?
Why do you think the door switch "feed" can be found at the light switch? can they be switched on/off from here then?
If you use a multimeter at the positions mentioned and operate the various items this will identify the cables you need to use.
The "starting current" is fed directly from the battery via a solenoid (mounted on starter motor) and possibly a relay as well, through the ignition switch.
I don,t mean to be disrespectful if you are not sure what your doing you could do some "serious damage" to the various control boxes/computers and wiring in your car if you wire the alarm incorrectly.
If you haven,t got a mutimeter with ohms and volt range on it get one because you "will" need it as even auto electricans would,nt do this without one.
To replace a central locking control unit could "easily" cost more than the price of a install.
N.B.
"Only use a vehicle wiring drawing as guidance" (especially Haynes) as they are generic all cables should be confirmed with a multimeter before connecting to the new alarm system.

 

[W124-300D]

I have all kind´s of welding tools, multimeters, insulationtape and so on.
The reason for why I´d like to use the cable behind the headlightswitch is because there is a delayswitch for the "indoor-light". This delay affects the alarmunit for about 30 sec., and every time the alarm is activated the alarm will get false info since the "indoor" light is on for a while. The alarm notices that the light is on, overrides that circuit for a moment and later the alarm tests the circuits again and will work properly.
This would not matter if all the other circuits never fail. If one of them fail the alarm will report it the same way it reports about the indoorlight. Of wich it allready reports, and other malfunctions would then be unnoticed?
On the other hand installing a led on the doorswitch cable would help this situation? The cable that goes to the alarm would then be connected between the led and the doorswitch?

 

[David R]

Typically the interface to the central locking will be done using the (usually) blue wire running to the pump.

Cut this, and wire it in such a way that under normal circumstances the alarm will join the cut wire back together (thus your locking will still work from the key).

When locking, the alarm needs to send a ground signal to the pump, and break the link on the blue wire (ie; the ground should only go to the pump and not back the other way).

When unlocking, the alarm needs to send a +12v signal to the pump, and break the link on the blue wire (ie; the +12v should only go to the pump and not back the other way).

But, as has already been pointed out, confirm all this with a multi-meter before doing anything.

 

[W124-300D]

wiring ideas / suggestions

I´ve made som dravings of how I see the problem.
Indoorlighting:

The diodes in the indoorlight-wiring will see to that the cars own lightdelay and the alarm lightdelay won´t give false signals to the alarm. I also added a few diodes to keep the front and the back circuits separate.


Vacuumpumpwiring:

This is the way a dealer says it should be connected. I would be very happy if someone could clarify the logic in this wiring...

 

[W124-300D]

Diodes...

New info:

The cars own lightdelaycircuit is positioned near the switch in the roof. This means that the horisontal diodes in my skech arent necessary. The alarm should not get false information without the two horisontal diodes.

But soldering is fun and diodes don´t cost a fortune. So there is nothing to worry about except the human factor and Murphys law...

 

[bigasotonuk]

i had a montego turbo long ago and this had an alarm (non genuine) it had a turbo cooling down fan that would switch on after the engine shut down and the alarm was programmed to ignore this it was a basic non approved alarm system. The spec of your alarm should include this facility so you can use it for your interior lights.

 

[David R]

The diagram you have of your central locking connections ties in exactly with what I tried to describe in words, so I would say that confirms it.

 

[W124-300D]

thanks

Nice to hear David R!
I tried to figure out how the relays work, half of the time it seemed all right and half of the time I got it wrong.
I have yet to make the connections, and I will report how it went.

 

[ig_Al_300te]

on the drivers side floor in the ducting there is a load of looms carefully slice open them and look for a loom containing a blue or green wire can't remember which one as its blue on one side and green on the other test with your meter it should rest at neg but go pos upon lock then you need to follow the alarm instructions for interupt locking configuration so basicly the feed (closest to the door) goes to the alarm then from the alarm to the pump side.

But as someone has said before test test test if you are stuck on doing the alarm yourself

P.M me if you want me to send you a car alarm diagram for your car.

Alex.

 

[1nevster]

on the drivers side floor in the ducting there is a load of looms carefully slice open them and look for a loom containing a blue or green wire can't remember which one as its blue on one side and green on the other test with your meter it should rest at neg but go pos upon lock then you need to follow the alarm instructions for interupt locking configuration so basicly the feed (closest to the door) goes to the alarm then from the alarm to the pump side.

But as someone has said before test test test if you are stuck on doing the alarm yourself

P.M me if you want me to send you a car alarm diagram for your car.

Alex.

Thanks for contributing, however the thread is 4 years old now...dont take this the wrong way just pointing out the dates on the original posts...regards Dave.