Central Locking Puzzle

[K04064]

Hello All.

I've been searching around the net and it looks like I'm the first person in history to have an issue with the central locking on the Mk4 platform....... (Octavia RS MK1)

 

I'm looking for opinions before I start taking the doors apart

 

The situation

 

I can't lock the car

 

New car to me. One fob was working when I got the car. Battery quit, then the one fob that was working, stopped working.

 

Turning the key in the drivers door has zero effect. 

 

Ive done a scan with VCDS. It tells me low voltage to Central Convenience "intermittent" (showing 11.9 volts) on VCDS
It also says no communication with any of the doors "intermittent"
"Interface for Data Bus - No comms, intermittent"
"Adaption limit surpassed" for both keys.

When I open either of the front doors, the blocks in VCDS says they are closed. Opening rear doors shows they are open.

Drivers door status is listed as "Safe". Always

 

When I pull the key out of the ignition, something happens with the locks in the door. A sound from all 4 doors. Nothing changes with the lock status.

What I've done

Pulled the CCM, opened it, resoldered the pins. No change
Cancelled the faults in VCDS. Faults come back immediately
Checked fuses. All okay.
Tried reprogramming keys with VCDS, nothing, no acknowledgement of the key when I press the fob button during the process.
I've ordered a new key, wont be with me for a few weeks

Possible pointers

 

The front doors not recognising they are open
Drivers door being "Safe"
The comms problem on all door modules. VCDS says if there are a ton of codes, probably one central issue.

 

Does anyone have experience like this?

 

What should be my next step?
What does this issue sound like to you?

I was thinking I could try unplugging the door modules one by one (at the door jam connector) and see if that changes anything

 

What do you reckon?
 

[Dean]

The wiring works on a looped system. So, if there's a break in a wire, it can affect other doors.

Just to rule it out, you should do a continuity check on the blocks to make sure that no wires are broken or melted.

[K04064]

Thanks for replying. I put a multimeter scope on the CAN wires and the signal seems to look normal. The number six fuse was missing, putting one in there seemed to change absolutely nothing.

 

I took out the drivers door lock. (top screw only, out slightly, ignore the Haynes manual...). Was expecting it to be mint. Imagine my surprise when it came out looking like something off the Mary Celeste. It also left a load of shrapnel in the aperture as an added bonus. The blade part of the mech is MIA, springs and clips are accounted for. Ordered a key barrel repair kit from Ali

 

Playing with the lock/unlock button on the electric window panel. At times the block in VCDS will show the driver's door as open/closed. And locked/unlocked. But super hit and miss, mostly 99% miss. Mostly locks with the button and then unlocks immediately. I'm assuming its the door module given the state of the lock barrel. Only drivers door misbehaving with lock status ie "Safe" 99% of the time. Ordered some micro switches from Ali. Hopefully the right ones. 

 

Looks like I'll be taking the door apart. Unless I can change replace the lock barrel from outside. Soaked door internals with WD40 through key barrel hole. Will report back when I have the parts. 

[K04064]

(Can I put a link to the micro switches so someone can tell me if I ordered the right ones?)

[Dean]

Sure, but it might just be worth buying a second hand replacement motor or using pattern parts.

[K04064]

OK. Noted for the motor.

The lock repair kit arrived. What a nightmare. Parts in the kit different sizes to the original parts. Tried to mix and match with the old parts no beuno. Good news is the central locking was working normally with the key. Bad news the lock disassembled itself. Ordered another lock kit which looks closer to the original stuff.

All the c**k**g about trying to get the spring lined up might have knackered the lock mechanism. Ordered a replacement lock just in case. Is it possible to order a lock, according to the pattern on the key??? Really dont want an extra key on the key ring.

 

Was using this video 

 - Makes it look about a million times easier than reality. Trying to use different sized parts didnt help I'm sure. I was dammed if I could get that c-clip to fit on the groove.

Thought getting the key working was going to be easy..........

[K04064]

The second lock repair kit arrived. This one from China. Much better. Much closer in size to the original one. This is the kit if anyone is interested. Spring strong without being overly strong. Parts very close to ideal thickness. Much easier to assemble. I could have taken half a mil of the c clip but it went on as is.

 

With the key assembled I put it back in the door and with a few turns left and right the central locking started opening and closing. Probably stiff from lack of use.

 

And as a Brucy bonus as I was turning the key towards the front I accidentally pressed one of the buttons on the fob which wound down all the windows. I wasn't sure what happened but after that the fob also started working again. Talk about two birds in one stone! Lock fixed and central locking. Hopefully the "fix" lasts..........

[K04064]

I spoke too soon. With the central locking working from the fob and the key I've noticed another problem.

 

A battery drain on fuse 14, the comfort module. About 0.5 amps. 

With VCDS I can see the passenger door is still not being recognized as open or closed. The drivers door with some cleaning now recognises the door is open and closed. Most of the time.

I can hear the microswitch being activated on the passenger door but nothing changes on VCDS.

Lock status for the drivers door is coming back as "implausible".

 

The microswitches have arrived but I've just been looking on autodoc and the lock modules are so cheap I'm just going to buy a driver's and pass module.