@Dabber2024 - believe u tagged the wrong @J.R.

@Dabber2024, from what you say about the dash display correctly showing door open/closed status I'd imagine there's nothing wrong with microswitch or its wiring.

Rather, when you go to enter the car, the interior monitoring sensor is picking up your movements and triggering the alarm, assuming you have 'locked' the car and so set the alarm.

 

Unfortunately,  I don't expect VCDS lite will work on a mk2 Fabia built from March 2010 onwards. 

Can't remember exactly why not, but never heard of anyone trying and succeeding with a Fabia younger than this.

 

On 01/03/2025 at 03:51, JR RS said:

@Dabber2024 - believe u tagged the wrong @J.R.

apologies

On 01/03/2025 at 07:25, Breezy_Pete said:

@Dabber2024, from what you say about the dash display correctly showing door open/closed status I'd imagine there's nothing wrong with microswitch or its wiring.

Rather, when you go to enter the car, the interior monitoring sensor is picking up your movements and triggering the alarm, assuming you have 'locked' the car and so set the alarm.

 

Unfortunately,  I don't expect VCDS lite will work on a mk2 Fabia built from March 2010 onwards. 

Can't remember exactly why not, but never heard of anyone trying and succeeding with a Fabia younger than this.

 

Hi Pete, agreed on the microswitch. I cant find the post I read about the car door locking unit which pointed me towards poor soldering in the unit. What with the interior sensor disable button not lighting orange when pressed and the iffy pattern of flashes of the little red indicator light on the top of the door card somethings amiss. Went to look round the breakers yard for a fabia alarm siren , none present, checked several golfs as well and passats , could not even find the alarm sirens on them ! i was looking under the front panel below the windscreen and also the drivers wheelarch , most odd, i must be lokoing in the wrong place. Anyhow I guess i will have to actually buy one from Aliexpress.

Lots of 2nd hand ones ebay at various prices. 🙂

7 minutes ago, Dabber2024 said:

 I cant find the post I read about the car door locking unit which pointed me towards poor soldering in the unit

Possibly my pic and vid?

 

The parasitic drain could be similar to a fault I had on old Volvo. The backup battery for alarm siren failed/shorted  and was taking charge all the time. Car battery would go flat over a few days if car wasn't being used.  i tracked the drain/wiring  down to the clock on dash but then discovered it also supplied the rechargeable battery pack in the siren. Not sure on the Skoda but it might be worth checking as mine eventually started heating up and smoking. I just removed siren etc as being an old car didn't see need for alarm.

Alasdair

 

Edited 2 March, 20251 yr by Alasdair1

On 02/03/2025 at 12:04, Alasdair1 said:

The parasitic drain could be similar to a fault I had on old Volvo. The backup battery for alarm siren failed/shorted  and was taking charge all the time. Car battery would go flat over a few days if car wasn't being used.  i tracked the drain/wiring  down to the clock on dash but then discovered it also supplied the rechargeable battery pack in the siren. Not sure on the Skoda but it might be worth checking as mine eventually started heating up and smoking. I just removed siren etc as being an old car didn't see need for alarm.

Alasdair

 

Hi Alasdair, thanks for the input, i had not considered the possible shared power supply to the siren. As it stands my siren was missing when I looked the other day, pretty annoying. The new one off Aliexpress is on its way !. So todays update is only to show what happened when I ran a scan using the TOPDON CARPAL. This is an obd2 scan tool with additional car specific libraries of info you can download and use, they have good reviews . I ran the first scan below and there were several error codes which my old school code reader would not have been able to see.

I have attached the detail of the codes as 1st scan details pdf and theres lots of implausible signal codes and an airbag code and then theres the 01134:004Alarm horn - No signal/communication Active/Static. Its the only code that was written in Red, the rest of them had text to tell me they were ok to ignore.

So I performed a DTC code clear and re-ran the scan and the only one left was the Horn code.

So, Im hoping that the old codes are indicators of some dodgy alarm related triggers from the door locks or something and the airbag code might be something from someone else doing work on the car. When the new siren arrives I will get it plugged in and try it.

There are 3 wires from the alarm siren earth, power and a communication wire which is either Lin Line or K line (not sure), I should be able to trace the signal wire back to the combined Voltage control Module/Body Control Unit (i hope). The possibility that the control wire is keeping everything awake is well documented either by ways suggested by Alasdair or otherwise.

Dabber

1st scan.pdf

On 02/03/2025 at 10:50, Breezy_Pete said:

Possibly my pic and vid?

 

Im not sure Pete, quite possibly , do you have a link please ? I would like to get some more knowledge as re-flowing the soldered joints is something I can do easily enough.

Ta

Dabber

Hopefully its because theres no alarm siren fitted and the car is trying to connect to it constantly. Not sure how most of the electronics work these days. Its a fairly steep learning curve with plenty of times you just end up scratching your head and end up on here.

Alasdair

It's a LIN wire from the alarm horn to BCM.

Link to lock microswitch (actually the earth) solder thing:

Locking misbehaviour, another possible cause - Skoda Fabia Mk1 (1999-2007) - BRISKODALocking misbehaviour, another possible cause - Skoda Fabia Mk1 (1999-2007) - BRISKODA

The lock repaired in that thread remains in service, fault free nearly five years on.

On 05/03/2025 at 15:17, Breezy_Pete said:

It's a LIN wire from the alarm horn to BCM.

Link to lock microswitch (actually the earth) solder thing:

Locking misbehaviour, another possible cause - Skoda Fabia Mk1 (1999-2007) - BRISKODALocking misbehaviour, another possible cause - Skoda Fabia Mk1 (1999-2007) - BRISKODA

The lock repaired in that thread remains in service, fault free nearly five years on.

This was the video ! Excellent knowledge that man.

New alarm has arrived need to get round to fitting it.

Update on TOPDON carpal readings...retested today after clearing all codes previously. The alarm missing code is back...and also the passenger door inaudible signal !

so.. hypothesis time...

The old owner had a dodgy door close signal

This set the alarm off intermittently

They decided to remove the alarm

The door locking signal fault is still there

The ECU brain is searching for the Lin wire thats commuinicating with the (missing) alarm

The ECU brain is now confused and somehow keeping the radio turned on in the background

When I clean and refit the alarm siren I expect to get it going off intermittently but I wont delve into the inaudible door signal fault till I have seen if the radio parasitic drain goes away ..

Watch this space

Sounds plausible.

Sensible plan of action, one step at a time is always best.

Well here I am again and its time to pick this problem back up.

So the gripping tale continues, as of last march I had put switched power to my radio to reduce the battery drain with the intention to perform further diagnostic with the arrival of a logging clamp meter, this is a bluetooth enabled DC volt clampmeter which allows me to measure current flow in a wire over a period of time in a table and graph. Given the previous information I gleaned regarding the water leaks from the rear washer jet causing a short in the rear wiper motor I was planning to clamp the power leads going into the wiper motor and see if there was a spike when the motor kept trying to "park" the wiper blade (as per stuff ive read on tinternet).

Naturally the clampmeter has arrived and ive still not got to grips with it lols. I have had a quick go using it on the rear wiper motor leads but i need to get in and have proper go.

So the reason for this update.

Mavis (our fabia) suddenly decided to stop responding to the key fob this week, i changed the battery and that didnt fix it, i then noticed that the little red light on the key fob was working anyway so clearly its not the fob, or at least the fob is good for power anyway. The spare fob also failed to operate the locks.

It has been raining heavily in our area this last week after the prolonged hot weather I should add.

We have therefore been locking and unlocking the car with the key, when doing so the only lock that opens is the drivers door lock, in order that we can open the boot i have to press the centre console mounted lock/unlock button and then go and open the boot as normal. When i press this lock/unlock button on the centre console (below the radio area of the dash) it makes an interesting pair of noises, normally it makes an unlock noise followed by the different and sort of "heavier" clunk of the deadlocks coming off, now it makes the initial sort of whining click noise and then repeats itself as if its started an operation and then reversed itself by performing the same operation. Its hard to describe but it now makes two noises that sound the same rather than the correct two noises that are distinctly different. Additionally at no point has the central locking activated itself to unlock any of the other doors, we have to use the internal handles to unlock them.

As you can imagine I have by now read many many articles on door locking and electrical gremlins, including @Breezy_Pete interesting article on reflowing the solder joints in the door lock where his earth joints were cracked. This article also ed in with something I read about the shared earth of the door lock unit contributing to the door button for disabling the internal alarms malfunction.

I have also read many articles on wires in the door cable grommets being cracket or broken and the issues these cause which can be varied.

As mention previously I also am pretty sure my rear wiper has been leaking over my rear wiper motor (theres a lot of rusty deposits and rusty number plate lights apertures) and causing the failiure to park problem which could be triggering a battery drain.

However the one thing I have not read so far in this saga is the most recent trick Mavis has pulled.

Basically having locked up with the key earlier today I came down around dusk to go for a drive in Mavis, only to find that the drivers front headlight and drivers rear running light were turned on !!! Note i say drivers side ONLY. The car was still locked and I dont thing the little red light on the door was flashing to indicate the alarm is on was blinking but couldn't swear to that. At which point my wife clicked the key fob opne button that hasnt worked for 5 days now, and the bloody car opened up !!! All the doors !!!

I have never seen this one sided malfunction occur before in my life, it is possible in my Talbot Talisman for this to occur because the right and left side of the vehicles lights go through different fuses and the main operating switch must send power to both fuses. Are Fabias wired up so that the drivers side lights go through a different fuse than the passenger side ??? And even if they do how on earth is it possible that power can flow to the lights when the car is locked and the key not even in the ignition ???

Somehow the car has turned its own lights on and unless the ECUor Body Control Module actually perform part of the power switching task between the manual switch and the light bulbs then I cannot see how this is possible ............UNLESS somehow power has been flowing from a short to the lightbulbs

Thoughts anyone ??

Dabber

The unilateral parking light thing happened because the indicator stalk was up (as if indicating right) when vehicle was switched off. Feature, not fault.

Door locking oddness sounds reminiscent of a situation where one door is being sensed electrically as open, despite being physically shut.

The two things together probably suggest that driver's door is being sensed as open, since exiting the car through that door with indicator non-central would normally give an audible warning in the same way as lights left on would. (Unless door open/closed status is not consistently correct in the electronics).

Experiment to confirm.

Edited 7 September, 20257 Sep by Breezy_Pete

Interesting read this. I had parasitic drain on my 2013 Fabia and the auto electrician was scratching his head until he pulled the Swing radio out and it did the trick. I've purchased a used Swing radio from a scrap yard and fitted it yesterday so carrying out a voltage level check on the battery today to see if ok now.

Always wondered why there are two Fakra aerial outputs from the radio but only one at the roof aerial base only to discover there's a separate signal amplifier somewhere that I can't find - picture here: