central locking type viper 1002

Just installed a viper 1002 on my Skoda Fabia 2002. Central locking is a manufacturer supplied aftermarket system. I assumed (that's the mistake I know), it was a negative multiplex system with 180ohms unlock resistance required like the factory fitted system and wired it this way. It will lock, both when locking and trying to unlock. I have tried looking here https://www.the12volt.com/doorlocks/doorlocks.asp but still feel stuck. There are 4 wires at each front door, 2 at the rear doors. These are the colours along with what I believe their operation is. Blue/grey - lock/unlock wire Brown - ground and the two wires also present in rear doors Blue - motor (polarity dependent on lock/unlock) Green - motor (polarity dependent on lock/unlock) I cut the blue/grey wire and tested for resistance from the motor to a good ground. When locked there is near enough zero resistance. When unlocked it is open circuit. Grounding the blue/grey wire causes the doors to lock. Breaking the connection after this does not unlock. Grounding the wire again the motors can be heard attempting to lock again. Tried testing the brown wire but it appears to be as I expected, just a ground. I noticed that if testing for resistance connecting the multimeter to both ends of the cut wire, breaking the circuit causes the doors to unlock. Any help would be greatly appreciated. Many thanks in advance.

Known as a 1 wire open circuit it can also be controlled by finding the lock control unit, all the blues and greens join together at some point, why not wire it as a 5 wire there. Your 1002 can handle either system.

Thanks Howie you're ever so helpful! Just tested again and I made a mistake in first post, if I ground the wire and hold it there a little, and then release it, it does unlock. Seems unusual for it to be "ground to lock" though - it seems they normally work the other way around, which would make sense for security as managing to cut a wire would leave the doors locked.

Yes I agree though I've seen both types. Ford Mondeos and early Transits (1998-2007) could be "got at" by running a sharp knife across the back door/tailgate loom and grounding it.

Central locking now working perfect! Thanks again. Another issue on the same install - zone bypass warning. Unplug door wire pin from harness and warning goes away. Door pin switches all test okay individually. Wired with one diode per door wire. Multimeter in diode test mode probing alarm connector and a good ground location shows ground for a second and then none with door shut, and constant ground when any door open. I guess the BCM is giving enough ground to trigger the warning. Do I need to insert another diode for each door trigger, stripe away from BCM before each door trigger is tapped?

Oh yes the old Polo/Transporter/Ford syndrome. For your further edification, although I'm sure you will get the diodes the right way round, look at DEI tech sheet 1076 on this site. Although that problem usually comes up after half an hour or so (the sleeper circuit). 2 Things..does your hatch light work properly, the microswitch (in the lock catch) almost ALWAYS fails on VWs. Set the alarm to domelight delay and see if the problem persists.

Excellent, 2 resistors for each door wired as per 1076 pdf fixed it. Had trouble figuring out how to connect to the interior light. Best I could tell it has one live feed, a constant earth feed, and a switched earth feed controlled by the BCU. I ended up connecting input to ground, and output to a door trigger before the diode. Can't seem to get the shock sensor to detect my hammering on the door pillars in adjustment mode (only detects full trigger I believe) even at max sensitivity. I fixed the brain using two klett-power 3m strips (bit like velcro but better) up to the sound insulation as high as possible up the underside of the dash by the glove box end. I guess the sound proofing could be "damping" the shock. But when I had a system with a separate shock sensor, I found zip tying it to a wiring loom made it more sensitive than fixing to a firm surface.