My son's Fabia has developed a fault with the door locks, and I'm looking for a clue where to start. The car has key locking only (it didn't come with a remote and I don't know if the feature was ever fitted). The issue is that using the key, the driver's door will lock and unlock all of the doors with the exception of the passenger door, and the key used in the passenger door will lock and unlock all of the doors with the exception of the driver's door. Anybody got any ideas where to start with that fault ?

I would start with a code read of the convenience system to see what is stored.

@tommoynihanWhat year & what spec / trim of Mk2 Fabia. 

Inspect door looms inside the bellows adjacent to the a-pillar connectors, both sides. Expect a broken wire or more at both locations.

@Crasher - ODBeleven reports no faults

@toot According to the V5 it is a Fabia 1 HTP 70 first registered in September 2007

@Breezy_Pete Yes - I have read some of your discussions with other members about failure of the loom in this area. I am no stranger to problems of this type as I have a Superb II with the twin folding tailgate/boot which I have had to repair. I may well have to resort to this type of inspection, but I was trying to apply some logic before I started to 'poke and hope'. I can't understand why the two doors with keyholes would be able to control themselves and the rear doors and tailgate but not each other UNLESS there was some dedicated connectivity between these two 'master' doors that had broken. If so, I suppose that could be explained by your broken wire theory/experience ?

Each door lock contains a small dc motor. The connections are reversible within the central convenience control unit so that it can lock, or unlock each. If either wire is broken, the motor cannot be driven from central command any more, so the lock can only by turned by key, mechanically.

I think your symptoms are consistent with at least one of these motor wires being broken on each side.

@Breezy_Pete Thanks for that info. That is indeed a possible/plausible explanation. Sound like I'm on the joyous Skoda broken wiring loom hunt again. As a side question, I presume that the central convenience unit can be enabled for remote control on some models ? If the car were equipped with remote control central locking (in future) it would maybe provide easier diagnosis as it would provide a third way of locking/unlocking the car that independent of the door locking mechanism and door wiring ?

Yes, there's a version of CCU that can be swapped in to upgrade to factory type remote central locking.

Bit more to it than just that.

Not sure if there's a 'how to' thread on here, but there certainly is on clubpolo.

@Breezy_PeteWell the driver's door loom looks fine. The passenger much less so. Picture attached. Two wires broken and at least 4 others damaged. Great design, but many thanks for the diagnosis ! On my Superb twinboot, once I had repaired it, I threatened all of my family to never let me catch them using it as a boot, but only as a tailgate (which means we can't use the button on the keyfob). Is there an way of stopping this happening again once repaired (other that climbing in through the tailgate) ? If I wrap lots of pvc tape round it is that just going to push the 'flex' elsewhere ? Why is the passenger door loom shredded and the driver's door loom look perfect ? Surely the use factor should suggest it should be the other way round ?

I'd repair it any old how for the time being, and see if any functions are restored, seems like some things ought to re-awaken.

Perhaps drivers side loom has been replaced before now?

 

 

 

 

@Breezy_Pete Yes, perhaps the driver's side has been replaced. We only know the history of the last 5 years. Will update once I have finished soldering ....

@Breezy_Pete Well, I am very sad to say that after repairing 2 wires and re-insulating 5 other wires on the passenger loom, and then re-inspecting the driver loom and finding cracks in the insulation on 4 wires UNDER the cloth tie that hold them all together and re-insulating them too, that it has made absolutely no difference to the locking behaviour :-(.

Oh, that's unlucky. 🙁

 

Does the car have electric windows? If so do they work?

 

 

@Breezy_Pete Yes it does (at the front), and yes they do work. I also scanned with ODBeleven again, but no new information I'm afraid,

Only other thing I can think is that both door locks have trouble with their motors.

Maybe try the following experiment with a helper.

 

With assistant at opposite door, get them to gently 'hammer' continuously with palm of hand on the outside of the door just below the handle, while you turn the key each way in the other front door, attempting to get all doors to lock and unlock. The idea being to just agitate the motor and gears that it drives at the time the current is applied to try to move it.

 

If there is now occasional correct function at either or both locks, I'd start planning replacement of at least the passenger side one, on the basis that if that does what it should while key-locking from the normal entry/exit door, the car is unlikely to be left accidentally insecure.

 

 

Accessing a test child now .... Will report back once the moaning is complete.

Maybe another clue? I've also had issues with son's Fabia MK1 2007 locks (reported yesterday)

When the driver's door lock failed, the central locking on the key fob would lock all other doors but not the driver's. But I could lock the driver's door with the key and it would also operate the central locking on the other 3 doors plus tail gate. Same with unlocking. Key would unlock drivers and all others but key fob wouldn't unlock the driver's door. 

Does your car have double locking?

@billwinUnfortunately, to the best of my knowledge, his car doesn't have central locking on a key fob. To be accurate, he wasn't given a central locking fob by the previous owner so we just assumed it didn't. I agree that if it did, it might help with the diagnosis. All I have got is the anomalous behaviour when I put the key in either door lock as originally described.

@Breezy_Pete  Well, I finally got a child up from the horizonal, and got them bashing on each door just below the handle as I operated the key on the lock on the opposite side of the car. When the passenger side was agitated, it made no difference to the behaviour. When the drivers side was agitated, we could get intermittent locking and unlocking of the drivers door by operating the passenger lock. This would suggest to me that the drivers door motor mechanism looks to be faulty/suspect. The passenger side could obviously still be faulty, but if so, more severely. 

 

I had stripped off the trim from the passenger door to look an unrelated speaker problem, and the door is not like the door that I have seen in other threads about the door locks. It does not have a very large window regulator plate riveted in, It has a 'normal' size window regulator plate in the middle of the door and it is screwed/bolted in. The is also a hole in the top left of the passenger door about where the door handle is. I've looked behind it and there is no sign of any motor mechanism just below the door handle. That said, agitating to door did make a difference on the driver's door, but I'm guessing that it was the general 'bashing'  vibrations that made their way back to wherever the motor is,

 

I'll have to have a look around and see if I can find out where the motor is located. I would presume that it should be very close to the door lock but it is evading me at the moment.

Lock motor is inside the lock module. 

 

I did understand you don't have remote central locking. I was just trying to explain in our case the key would operate the faulty lock and all others, but the 'normal' method won't operate the faulty lock. The thumping on the door to occasionally get the lock to work is the same as I had with son's door lock.  As Breezy_Pete said, motor and lock are in one unit.

When son's rear door lock failed (see my other post, I've changed three) I resorted to a rubber mallet to hit the door while operating the central locking to get it to release. Otherwise I don't know how I'd have managed to change the lock. Double locking prevents it opening from the inside.

@billwin Apologies, I now understand that you were to the 'normal' and 'thumping' methods. As @Breezy_Pete suggested, I'm going to take off the passenger side one first as if that can be repaired or replaced, then it gets the car to a normal workable situation. and we can then consider if we want to do anything about the driver's side (or wait for it to deteriorate). Do you happen to know if the part number for the lock mechanism changed between to Mk1 and the Mk2, as this car is an early Mk,2

Message me your VIN and I can look up part number for you. 🙂

Sorry, I don't know if the part changed. Son's Fabia is 07 reg.

Photos on auction site look identical for MK1 and MK2 and one advert I found states it covers both. But may depend on other factors.

I assume your son's car has a door lock button inside. Can you lock and unlock all doors using this button?

 

Another possibility for the persistent failure is the fact that a live 12V and a ground cable look damaged in the loom. This could have burnt "something" on the PCB of the door controller.