remote central locking on ford focus

Hi There, I just happened on the forum i need a lick of help. I'm installing an aftermarket remote central locking/alarm unit on a 2000 Ford Focus Estate (right hand drive..I'm in Ireland!). It was a cheapy ebay jobby and i've decided to use only the central locking function and not bother hooking up the alarm part of it. I've connected it to the car's +ve power, the earth, the indicators etc but i caNNot get the actual locking/unlocking function to work. I found the wires that lock/unlock the doors(drivers door locks all doors) and there's a constant 12V across it when i test it with a multimeter. When i hit the lock/unlock button on my door the voltage drops to zero and the door locks/unlocks. I've hooked the right wires up to the locking unit of the car but the remote central locking unit will not do anything besides flash the hazard lights and make some clicking noises. There's 0V across the wires from the aftermarket unit and when i hit the remote fob it'll push 12V across it. But i need it to be 12V and then zero when i hit the button. Any advice would be greatly appreciated as i spent hours working on this today and cannot figure it out. the unit was bought from ebay but i haven't got any useful replies from the seller. Thanks in advance Marcomolo

thanks, the alarm is a no-brand thingy. It's a green connector (with wires coming from the door locks, boot release, etc)which hooks into the central locking unit(already built in). two rows of eight wires.but there is a good few spaces, so not actually sixteen wires. thick yellow/black = lock (pin 1) thick WHITE/ black = unlock (pin 2) thick WHITE/ black = unlock (pin 3) as in there were 2 WHITE/ black wires. they both did the same when i multimetered them. 12V constant and when i hit the door lock they zero. But my aftermarket remote unit SENDS OUT 12V when i hit the remote. surely diodes won't change that? I'm not using the alarm function, just the remote central locking function.

##quote## It sounds like the aftermarket unit is sending out 12v+ when you push lock/unlock on the remote, right? If I read that right, what you will need to do is wire up two relays to change the polarity of the output. relay #1 85 = lock wire from aftermarket unit 86 = ground 87 = ground 30 = lock wire in the car. relay #2 same except use unlock wires where lock wires were listed. /##quote## thanks i'll give it a go.

hello again, Thanks to mobile1 for the relay idea but i've since discovered the infamous 'blue wire' on my alarm unit. It's a negative trigger wire. and i've figured out that when i connect it to one of the door lock or unlock output wires from the alarm unit it gives off 12v and drops when i hit the remote. BRILLIANT i thought. except that when i hook it to the exising door lock wiring there's zero voltage and nothing more. I actually went to use a relay today and took the diagram from the12volt page on how to reverse the polarity -ve to +ve.but i couldn't get and voltage reading off the door lock/unlock wires from the alarm unit. I'm not sure what i'm doing wrong. i've tested the siren and Hazard light outputs from the alarm unit and they're working fine! Please help,It's cold at night and as much as i enjoy messin around with the car my ass cheeks are gettin cold! Thanks Marcomolo