Central locking

[2camjohn]

I am about to fit a keyless entry system into my car.

It activates the central locking remotely.


Before I started cutting wires in my car I powered the system up to make sure it works.

The relays inside the unit appear to click on command from the key fob.

Next I used my multimeter to analyse the signals that go to the central locking. It appears as though nothing happens with these four wires.

I measure no voltage across any of the wires, in the locked and unlocked positions and all four wires are not connected to each other (ie the resistance between them is infinite) again this is in both the locked and unlocked state.


So my question is how does central locking work?
My car has four wires which go to each front lock (where you can unlock and lock the doors) and two to the back ones (where there are door locks but nowhere to put a key).

How would the four wires from my keyless entry unit, which appear to do nothing, unlock and lock my doors?

Am i missing something really obvious?


Thanks in advance for your time.

 

[tansis]

The door locks are open and closed using motors.
The motor is normally connected with one side perminantly to the
"12 Volt" supply the relays connect the other side to the ground.
hence no readings with a volt meter

 

[2camjohn]

Ah right.


The thing is: I need to attach another relay to the keyless entry box, which is closed when the doors are unlocked.

How would I read the signal from my keyless box?

 

[tansis]

In the abscence of manufactures circuit diagram it's hard to say what method should be employed, in times such as these I resort to the sayings of my tutor ...
"sometimes the simplest solution is a switch"

Mount a magenet using epoxy on the mechinism were it will not interfere with the locking action, along with a reed relay on the door frame/skin.
I know, it's more fiddly but is less complex, plus you can get feedback from the front and rear door status.

 

[2camjohn]

Thanks for all the help so far

I can scan in the schematics from my Haynes manual if that will help you work out how I can wire it.

The problem with the method you suggested (puting a magnet on the lock mechanism) is that I need to place my circuit (which activates my immobiliser) under the dash, not in the door. The wires which run from the front of the car to the door are wired to a manufacturers plug as they pass though next to the hinge, so I cannot send my own wires into the door!

I want to wire up a 3 way relay to the box, so that the contacts are only closed when the car is locked. If I need to I could put a PIC in there, but I need to be able to read some sort of output from the keyless entry box.

Thanks for your time.

 

[tansis]

If there is one thing I must do before I die..
is pour my pint of beer over the head
over the swine who creates those ass backwards
unreadable, tangled mess that "Haynes" refer to as
wiring diagrams.......

Now that I've got that out of system, yeah upload the
diagram and will have a look for you.

Dont let that plug on the door scare you!
Though I cannot speak for your make/model
my experiance with the ford mondeo version is that allthough the plug is a sealed unit there is however ample room to thread 7/0.2 wires around the fitting and tie/hide them behind the connecting hose sheath. It is tricky to undo the bulkhead fittings and small hands do help. The rubber hose/compression seal is slighty compromised by having the wires under it but a liberal dollop of vasaline will help stop any water ingress, dont be tempted to use a bathroom or gasket sealent, you will never get into it again else!!

 

[2camjohn]

**broken link removed**

The lock thing does scare me.....slightly

The circled bits are the front door locks.

Any ideas ?

 

[2camjohn]

Can anyone help me with this problem?

 

[2camjohn]

Please can anyone help me on this matter.


I am currently driving a car with all the ignition and fusebox in peices all over the floor, it looks like I have just stolen it :evil: :cry: :evil: :cry:

 

[tansis]

Take your meter and set it to read volts dc ,
then using a pin or blade from a schlock connector pierce the yellow and brown wire and measure the voltage with respect to the chassis gnd / 0v
first with door unlocked , then locked... repeat process for white and brown wire.
One of then should be reading 0volts all the time when the door is locked

 

[squiz]

john i have fitted an after market remote c/l system...i also had problems but the first thing i was told was to find out what type of lock you have eg....positive pulse....negative pulse....positive and negative pulse....
then its down to the diagram supplied with ur system..it took me a while but i figured it out to work...give or take minore things that im still tryin to sort out(the alarm sounds when i press fob to unlock after locking with it.)..also what car do you have? or did you say that.

 

[picbits]

I'd have thought that after 4 and a half years he should have sorted it by now