central locking and key fobs ect

[doyle]

again a seat ibiza problem, same car 1.2 2004, however this time key fob doesnt open passenger door, it has to be manually opened from inside.
when trying to open door from inside it doesnt open first time but opens second pull of lever, given this i can out rule the key fob itself but i am thinking but not sure whether there is a motorised unit/mechagnism for the central locking etc.

problem external handle does nto open door and reamins locked(can this be a failure on mot)
internal handle operate on second pull
door does not unlock on fob demand

so to me it appears that what ever contol unit is in that door is defective so does anyone know what im to look for and how to test it

cheers for all help guys

terry

 

[alan333]

I've not worked on any Seats but generally speaking your theory is correct. Inside the door there will be a small electric actuator, which simply pulls/pushes the lock mechanism. It works on a signal from the master door lock, normally the driver's door. It will be easy to locate once you have the door card off, normally a small box with a coat hanger type wire coming out of it and attatching to the lock mechanism. The last one i took apart worked on a pulse signal rather than a change of polarity. Another thing to consider is that if the door lock is stuck part way between locked/unlocked then actuator won't be able to move it. Again this should be clear with the door card stripped down.

 

[doyle]

thanks alan,
i dont understand the pulse signal bit and would be unsure how to test that, was kinda hopin it would be as simple as using a multi meter for volts resistance and polarity. i take it when you say polarity the live changes wire or somert so polirty is reversed to and from on each change from lock to unlock, sorry for not bein clued up to much im a student mechanic in midlife change of career.
regards
terry

 

[Belle427]

Start with lubing up the latch mechanism on the door, wd40 will do to get you started. Open and close the door as you do it and try to lock etc, if this fails then its door panel off time you can then see the actuator and its linkages.

 

[alan333]

What i mean by pulse is that instead of there being (for example) 12 volts present when the lock is locked, and 0 volts when unlocked - instead there was a short pulse burst of 12 volts when the lock was activated/deactivated. I can't remember if the polarity reversed or not tho. It's still easy enough to check with a multimeter, you just need to constantly watch the display when operating the master lock.

 

[doyle]

thanks CH will do that first

however hopefully someone might be able to give further assistance, ive looked at the wiring diagram and cant fathem it out in one or two aspect.

from what i gather from it power goes from batery to engine fuse box to passenger fuse box to what is called convenience system control unit that distributes voltage to all doors so teh door affected will have a brown earth wire, a blue/ purple and a blue/red to teh motor which i presume is live neutral which another blue/red which has a resistor+ switch( i think would be a live) now this is where im lost after those inputs there is another wire that goes to what is called on board power supply control unit.

all locks have one wire going to it at a guess what im thinking is that the driver door lock is master lock that feeds a live to operate all other locks am i right in saying that are my understanding right...ill try to upload a copy of diagram and link it soon as i get a new printer maybe someone might pick up on something that i might not have understood to well this is a last minute conclusion as im typing

 

[Mursal]

Yes circuit diagram would be good
Would you have a broken wire in the boot that covers the wires as they go into the door from the pillar?

 

[alan333]

Firstly there might be more than one "master" lock. ie on some cars operating the passenger door lock initiates the central locking, or even the boot lock. Perhaps this would explain the number of wires in your set-up?

I'll try to clarify my last post a bit too. I can't remember how many wires the last unit I stripped down had, but it was fairly simple to check that the actuator was receiving it's signal.

I used a multimeter across each of the wires and expected a pair to be +12v when locked and 0V when unlocked (or the opposite way round), but this wasn't the case.

What I found was that after finding the relevant pair, I got a flash of 12v for a millisecond (well, probably a few milliseconds but you get my drift) at the time I locked the car using the master lock. Similarly I got a flash of +12v from the relevant pair when unlocking. I can't remember if both the locking and unlocking voltage flashes were from the same pair of wires, but thinking about it they probably weren't, or perhaps they were the same pair of wires but with the polarity reversed.

You won't do any harm checking for voltage on the wrong wires, so it's a case of checking them all in turn, with each other wire in turn, until you find two pairs which do something.

They work on a pulse because the actuator has a "rest" position. When activating "lock" the actuator extends in length for a millisecond to push the lock mechanism, and returns to rest. Similarly unlocking retracts the length and returns to rest.

As CH says - try lubricating first. Also bear in mind the if you strip the door card off remember that the lock probably wont operate unless the car thinks the door is closed. So you'll need to push the lock striker with a screwdriver or something to fool it into thinking it's closed.

 

[doyle]

im presuming the master lock is the drivers door due to it being a three door car and doubt the boot lock is the master lock.

i cant find the on board power supply unit location listed in the manual to test that master lock signal output to the n/s door, i can test later to see if signal is recieved at lock if not ill see seat to ask them its locations.

using a multi meter how do i test the resisters in the door lock assembly ie: settings, do i put it on olms and touch contact either side

i asked my tutor who has said the same as alan that iw ill only get a flash of voltage on primary circuit so have to lock unlock car on each test that i do, by the looks of it the garage that passed it through auction may have been into it already not sure found covers in the boot to eobd and a few other little covers lick side trim nr door.
thanks for all your help ill let you know how it turns out.