Hi all. New to this forum having just bought the car. The problem I have is random locking problems. Sometimes all doors lock/unlock. Then just drivers side or all except passenger rear door. I've replaced the microswitch on the drivers door which has cured the sidelight warning buzzer not working. The interior light works as do the puddle lights. The boot switch doesn't work either, but it will open on the remote or the interior pull. I've bought 4 new door catches but I'm thinking the problem may lay somewhere else. If the passenger door is opened and closed, that sometimes makes that side of the car locks work, but not all the time. Do the rear locks work as a slave from the drivers side front/passenger side front or are they independent. Any advice appreciated. Thanks Si

Have you checked for broken wires inside the rubber door to body bellows? It's pretty common for breaks to occur there. They can sometimes make intermittent connection too. The break can even be inside the wire insulation. Sometimes the wires are very obviously broken, though. The connections at the plugs at the A-pillar connection station can be problematic too. The lock units can develop dry solder joints as well.

 

https://www.briskoda.net/forums/topic/473390-lockingunlocking-issues-and-probable-cause/

 

Edited 19 September, 20205 yr by TMB

Hi, thanks for the reply. I've only taken the drivers side bellows off to remove the door carrier. The only broken wire I found was the white/purple which I soldered back together. This sorted the alarm led not working. Do both sides of the car work independently or are all locks activated by the drivers side? Thanks again for the reply. Si

If the driver's side lock is faulty it can affect the operation of the rest. There are microswitches inside that need to be working for the system to function properly. Also, bad solder joints in the lock unit caused by the repeated slamming of the door over the years can cause issues. The brushes in the little DC motor can get gummed up too.

 

Microswitches numbered 1 to 4 here....

 

Edited 19 September, 20205 yr by TMB

Try unlocking the car then just open the front passenger door, see if it re-locks after a short time as if you hadn't opened any doors.

Repeat for each rear door in turn if the car passes that test. If it does re-lock, the door open switch on that door isn't working reliably.

 

On our Fabia, the fault was a solder joint rather than the microswitch, but you may as well change any that you visit, as well as checking solder joints very carefully.

Both the re-locking fault and the random locking/unlocking whilst on the move have been resolved since that joint was fixed.

 

Yeah. Like I said I've changed the micro switch on the door lock. But haven't opened it. I did change the lock unit today for a new one, and locks were same. Couldn't open the door once locked though, so cut microswitch off and soldered it to the old door catch. The garage I bought the car from had locked the keys in the car and so after damaging the door handle and trying to prise the door frame out, they broke the rear quarter window. I fitted the new aftermarket catch and the door wouldn't open with key or remote. Replaced with the old lock and same problem

So I cut off the microswitch from new unit and fitted it to the old one. Same problem. Then I fitted a second hand door handle and this solved the door problem as in I can open and close with key and remote. But the other doors work/don't work as and when they chose? 

Too late for me to untangle all that info, but this was my recent experience: 

 

Thanks wino. Will try that tomorrow. Annoying thing is I fitted a new lock mechanism today and once the door closed it wouldn't open with key, remote or internal door switch. Finally managed to open it after banging the door lock. Put this down to a cheapo ebay purchase. So cut the microswitch off and soldered it to the old lock unit. Same problem. Now, the garage I bought the car from had locked the keys in the car and had yanked the door handle out so it didn't spring back, and ended up breaking the rear quarter to get in. Replaced the door handle and this solved the door opening issue but central locking still playing up?? 

Please do not shoot the messenger. But in domestic appliances subjected to normal temperature fluctuations soldered joints perform well . However in situations where the temperature can rise/fall outside of this solder can and does cause problems. Extremes of temperature can cause the solder to crystallise with the flux and although the joint seems sound, it is in fact a wire insulated by flux from the solder. British rail found this on soldered joints on tracks and changed for crimped connections. I've found similar on Monitors where the connections on diodes on a monitor became poor conductors with age. On a radio transmitter I worked on, all the coil terminations were made with plumbers solder due to this problem.

Cure- reflow with flux and a hot iron. On many occasions, the problem can be seen using a jewellers eyeglass with stress on the soldered joint to see if the terminations move.

Doors not opening from the outside after 'intervention' can be simply down to the little 'stepped peg' that links handle to lock going back in the wrong position.

I'll add a photo later if it's not obvious what I'm referring to.

Thanks wino. I've got the door handle sorted. I'm going to take the bellows off of all doors later to see if there are any breaks in the wiring. I'm thinking that the problem is possibly a broken wire or bad connection somewhere as I can hear the rear mechanisms working sometimes and then not, when locking/unlocking the car. Also sometimes even when you can hear them working the door still doesn't unlock if that makes sense? I'm thinking I'm probably going to have to pull the central locking fuse and live with locking the car manually. 

10 hours ago, Wino said:

Doors not opening from the outside after 'intervention' can be simply down to the little 'stepped peg' that links handle to lock going back in the wrong position.

I'll add a photo later if it's not obvious what I'm referring to.

 

This thing?....

 

.Thanks. The door handle problem was due to the handle carrier spring being damaged when garage was trying to break into the car. That's all sorted now. I thought it was the part you pictured causing the problem, and was trying to use that to tension the door handle until I worked out the problem. Central locking is still not working properly. Mainly passenger side. Front door seems to work most of the time but the rear passenger doors not locking at all now. Thinking I'm going to change out the door catch and see if this sorts it🤞

Please let us know the outcome, hope it goes well. 

Will do. Thanks for the help and advice. Si

If it's any help, our Roomster will lock all doors via key. Remote control will lock all doors on first push except front passenger door, second push same. Third push locks all doors and arms the alarm!

Also if only one push is used on remote, locks can be heard unlocking and locking intermittently.

If anyone knows why, information will be much appreciated. I am delaying going looking while I have a solution.

OK. Changed the passenger side door catch today. Both front doors locking/unlocking fine with key, remote and lock switch in the car. Rear doors still intermittent locking and unlocking. Door open warning light now works when passenger front door is opened. Next step is to change the rear door catches to see if this sorts the problem. Also changed anti rollbar bushes, steering rack gaiter, strut bearings, drop links and both front brake flex hoses. All on a car that was mot'd 2 weeks ago. 🤔

OK, just an update. The passenger rear door dead locked itself a couple of weeks ago. Seemed  like there was no power to the lock. I tried the usual banging around the lock whilst pushing the lock/unlock buttons on remote and door switch. No joy. Door was stuck shut. Phoned a couple of locksmiths and they didn't want to to know. So I thought I'd sort it myself. Easy fix as long as you have a new lock assembly (15 quid on ebay). I've read some posts about using a dremmel to cut away part of the lock casing to wind back the gear cogs. Far quicker and easier to chisel off the plastic part of the lock. Once the motor assembly is out, the mechanical side of the lock springs down and unlocks the door or you can get a screwdriver in to unlock it manually. Took about an hour to sort. New lock in and working fine👍