Modifications to Locking System

smokes24

Newbie
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moon
Car
S3
Hello everyone,

I am looking to get some info on how I can connect to my car's locking system so that I could install an RFID card reader that, when scanned with a valid card, would un-lock the car.

In my mind, it would work like this. An onboard micro-controller would process the signal from the RFID card reader, and if the card is authorized, the micro-controller would energize/close the un-lock side of the relay and the doors would unlock.

Is it as simple as just finding the lock switch's relay and splicing some wires to the proper terminals? One thing I have been wondering about is the power needed to un-lock the doors. On most cars, is this a 12-volt relay? Or is the voltage needed going to be different across makes and models?

Thanks in advance for the assistance.

Smokes
 
Greetings and welcome to our TorqueCars forum :)



The easiest way for you would be to buy an additional slave door solenoid kit (Singular) available from Maplins for about fifteen pounds. Then fix the slave solenoid with the bracket supplied so that you can connect the new connecting rod (supplied) onto the existing connecting rod going from the original door solenoid and on to the lock itself. If the original solenoid does not have 12 volts dc but uses a more obscure voltage then it would be best to adopt my suggestion of using a slave solenoid and run a 12 volt dc supply into the door through the loom. I would suggest you rig a temp supply to the slave solenoid maybe via a cigarette lighter plug (easier to connect and disconnect for testing purposes) so that you can make sure the travel is correct on the connecting rod i.e. it pulls the door solenoid and locks and unlocks the car properly. Note! most doors will have to be closed to able to do this, so make sure you have your car key in your pocket and the back window lowered, not the front window obviously as you will need access to the slave solenoid.

Once this is all done and you are happy, check the original solenoid connection for a permanent 12 volt dc supply i.e. you get a live when the key is out of the ignition. If you have one then it means you can use the 12 + volt supply to power your slave solenoid. The trigger therefore will be done via the negative connection cables (do not confuse this with a ground connection) on the slave solenoid. Now depending on the model bought it will have either one or two negatives to do the door open and door close function. These two wires will then run back to your RFID card controller and then connect it to the relay across the normally open and normally closed contacts with the common of the relay connected to a good earth point. This may have to be done in reverse if the solenoid uses a 12 volt + trigger to open and close the relay instead. You may also get the model solenoid that just uses two connections only, so this means a relay used will have to swap the polarity to the slave solenoid to effect the open and close motion of the solenoid.
 
Does your car have deadlocks?

What other types of locks are there? Magnetic? I am not completely sure as it has yet to be determined what vehicle models this thing would be installed into.

This project might interest you then http://www.instructables.com/id/RFID-Car-LockUnlock-v10/

I quite like this idea.

Most systems in cars use 12v lines and they will step this down as required.

Great vid! This is exactly what I have in mind.

Greetings and welcome to our TorqueCars forum :)



The easiest way for you would be to buy an additional slave door solenoid kit (Singular) available from Maplins for about fifteen pounds. Then fix the slave solenoid with the bracket supplied so that you can connect the new connecting rod (supplied) onto the existing connecting rod going from the original door solenoid and on to the lock itself. If the original solenoid does not have 12 volts dc but uses a more obscure voltage then it would be best to adopt my suggestion of using a slave solenoid and run a 12 volt dc supply into the door through the loom. I would suggest you rig a temp supply to the slave solenoid maybe via a cigarette lighter plug (easier to connect and disconnect for testing purposes) so that you can make sure the travel is correct on the connecting rod i.e. it pulls the door solenoid and locks and unlocks the car properly. Note! most doors will have to be closed to able to do this, so make sure you have your car key in your pocket and the back window lowered, not the front window obviously as you will need access to the slave solenoid.

Once this is all done and you are happy, check the original solenoid connection for a permanent 12 volt dc supply i.e. you get a live when the key is out of the ignition. If you have one then it means you can use the 12 + volt supply to power your slave solenoid. The trigger therefore will be done via the negative connection cables (do not confuse this with a ground connection) on the slave solenoid. Now depending on the model bought it will have either one or two negatives to do the door open and door close function. These two wires will then run back to your RFID card controller and then connect it to the relay across the normally open and normally closed contacts with the common of the relay connected to a good earth point. This may have to be done in reverse if the solenoid uses a 12 volt + trigger to open and close the relay instead. You may also get the model solenoid that just uses two connections only, so this means a relay used will have to swap the polarity to the slave solenoid to effect the open and close motion of the solenoid.

Awsome, thanks for this write-up.
 
I was thinking of approaching it from the input side rather than the mechanical side. I meant deadlocks that make the car unopenable from the inside once activated.
 

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