I found this thread while wrestling with my new(used) 2007 MKV.
When I picked it up 2/4 doors locked with 1/4 dead locking, this years been financially destructive so I aimed to get all my locks working for £0 or as close as possible, this thread in particular was of interest to me because I immediately found one of the barrel lock blanks was stuck...
I’d like to share my experience, thoughts and solutions to the stuck barrel and servicing of the locking mechanisms.
My car, like most it’s age has been fiddled with before, when doing the doors the most obvious sign is the plasters covering the handle mechanism torx screw either missing or part unstuck.
See YouTube for some excellent tutorials on door skin removal, 12 turn technique should always work.
If you are not familiar with doing this pay extra attention to feeling/part pulling the handle, as the ring turns it catches and holds the handle spring under part tension and helps when refitting the handle in the door, you can do damage by binding the barrel release ring up if you don’t pay attention here, if you see/feel the handle bind up, wind the torx screw in a bit and try again.
If the 12 turn technique (make sure you keep the handle part open) hasn’t worked check that there is a tab visible at 6 o’clock of the torx screw head! On mine it had been bent over and the screw head simply wound past it, in this case use a magnetic screwdriver and completely remove the screw to allow more access, it’s doing nothing anyway, now you can fashion a loop out of fine wire and catch and pull the mangled tab on the barrel retaining ring, hey presto!
The cause of this was incorrect previous assembly(screw tightened onto the release tab instead of installed between the release and back tab, I was able to straighten out the ring tabs and pre assemble the handle retaining mechanism once the door skin was off.
There are plenty of pics of these parts online, checkout the ring mechanism, it’s well designed to prevent failure/stuck issues so if yours is stuck it’s probably been put together wrong, add a little penetrating lubricant to make it even easier.
Servicing the locking modules; there are two fairly distinct parts, the mechanical/hardware side I will not cover, I don’t believe there are many failures happening there.
When you tear down the electrical side you’ll find a PCB, 2 small DC motors, 3-5 micro switches and 1-2 resistors.
Check the PCB, micro switches and resistors with a multimeter, on mine 1 door had a bad circuit in the pcb, all micro switches and resistors were fine (there are replacement micro switches and resistors all over the net for pennies incase you need something)
I fixed my pcb with some extra solder. This door worked sometimes in warm conditions and sometimes if you hit it.
Looking at the motors two things struck me, they do very few revolutions between locked and unlocked/deadlocked (one locks/unlocks, one is deadlock on/off), they are orientated in such a way that any detritus that is generated within them will collect around the brushes.
On inspection my motors all felt a bit sticky and the magnetic poles almost non existent.
Frustratingly replacement motors are hard to identify with certainty, the big corporates that produced them don’t publish specs and they don’t appear for resale anywhere I could find.
Back out with the generic ‘fixes everything’ penetrating lube... I started by soaking the motors and spinning them back and forth by hand to loosen things up then tipped the motors down to allow the muck to drain out followed up by another soak, then I ran each one on a 5v circuit back and forwards.
Just repeat until each motor operates reliably. Pay particular attention to stop/starting repeatedly to be sure there’s no sticking points.
The failure point is when you apply voltage but the motor doesn’t turn, cause being dirty/worn brushes. This is prone to happening more frequently in these locks because the motor always stops/starts from the same two points.
If this happens in the deadlock motor in the locked position you will get the ‘door stuck shut’ problem.
If the other motor fails you’ll get ‘doesn’t lock/unlock’ but will still be able double pull from the inside to open, assuming child locks are off!!
ECU codes thrown will likely be; 0155x 0009x 009xx ,x dependant on what door is playing up. 01038 central locking thermal protection may also be in the DTC.
If you want to open up the motors and be even more thorough go ahead, there’s a vid somewhere on YouTube for that. I didn’t because I wanted to first try this solution.
This is day 1 of all my locks working (and coming home lights! YAY!)
Will post here again when I have to take a door skin off again incase anyone is interested.
Total cost, swearing only, lucky I had all required tools, warning, you’ll need tx9 which is unusual ish.
