Oddest central locking issue in my early R53 cooper S

[mikeyr]

Got the strangest symptoms when locking my car via (two button) key fob. Any thoughts on likely cause?

• Locks 50% of time perfectly fine from keyfob when parked
• When not working the car won't lock from keyfob, the locks will go down, lights flash but then they immediately rise back up again
• Autolock works perfectly (E.g. locks itself once start driving)!!!
• Car will lock if I put physical key in lock and hold it, after a couple of attempts it'll 'out fight' it's desire to unlock itself again

When I disconnected battery for a few minutes it resolved itself for a couple of days

Thoughts so far were a sticking lock (but then why does it autolock with no issues)? Could it be related to the windows drop in some way? Sometimes the passenger window doesn't drop when opening the door but this doesn't always seem to coincide with the lock issue.

Thoughts welcome!

[paintman]

I've had similar problems with all three of the Pug 306s we had which are due to the wiring in the swan neck between the drivers door and A-pillar. Due to flexing the wires eventually break although the ends stay near enough that it can work intermittently.

[Mroad]

Sounds like a typical microswitch issue which is used to sense door opening/closing. Either an issue with the wiring or the microswitch itself. If a door is not sensed as shut then the locking will bounce back open. Likewise if it can't sense when the door is being opened then the glass won't move. Autolocking when moving probably failsafes ignoring the microswitches (it assumes the doors are shut).
I had a similar issue on a different BMW (lock bounce and no window drop) and had to replaced the microswitch in the end.
It might just need an adjustment of the door striker plate, a clean of the microswitch, a bend of the microswitch operating arm (depending on how it's operated) or more drastic in replacing the switch (if it can be got to) or checking of the wiring.
A garage would replace the latch assembly as microswitches aren't available separately, sounds like the passenger side is where the issue is.

[Penelope Stopit]

Mroad said:

Sounds like a typical microswitch issue which is used to sense door opening/closing. Either an issue with the wiring or the microswitch itself. If a door is not sensed as shut then the locking will bounce back open. Likewise if it can't sense when the door is being opened then the glass won't move. Autolocking when moving probably failsafes ignoring the microswitches (it assumes the doors are shut).
I had a similar issue on a different BMW (lock bounce and no window drop) and had to replaced the microswitch in the end.
It might just need an adjustment of the door striker plate, a clean of the microswitch, a bend of the microswitch operating arm (depending on how it's operated) or more drastic in replacing the switch (if it can be got to) or checking of the wiring.
A garage would replace the latch assembly as microswitches aren't available separately, sounds like the passenger side is where the issue is.

Good post this one and I can add a bit having read through it.
Autolocking may also work because you have opened the door and slammed it, thus disturbing the fault, I don't know if autolocking ignores the micro switches

[S0 What]

Penelope Stopit said:

Mroad said:

Sounds like a typical microswitch issue which is used to sense door opening/closing. Either an issue with the wiring or the microswitch itself. If a door is not sensed as shut then the locking will bounce back open. Likewise if it can't sense when the door is being opened then the glass won't move. Autolocking when moving probably failsafes ignoring the microswitches (it assumes the doors are shut).
I had a similar issue on a different BMW (lock bounce and no window drop) and had to replaced the microswitch in the end.
It might just need an adjustment of the door striker plate, a clean of the microswitch, a bend of the microswitch operating arm (depending on how it's operated) or more drastic in replacing the switch (if it can be got to) or checking of the wiring.
A garage would replace the latch assembly as microswitches aren't available separately, sounds like the passenger side is where the issue is.

Good post this one and I can add a bit having read through it.
Autolocking may also work because you have opened the door and slammed it, thus disturbing the fault, I don't know if autolocking ignores the micro switches

Also once the car int warms up the soldering grows and makes contact so works again, had many a Mk5 golf in as the temps drop where doors wont lock or even unlock unless you put a hair drying on the lock area for a while then they will work as intended, usuall fix is a strip and resolder of the switches.

[mikeyr]

Thanks all, it's been fine for a couple of days so waiting for it to return. The latch/microswitch seems a likely option (and apparently is a weak spot on these cars). I'm hoping a trend will appear of it happening with one of the doors in particular so I can then replace the correct side.

[mikeyr]

Update to this (thanks for suggestions all) - I've gone about 10 days without the issue reoccurring.

Don't know if this is coincidental or not but yesterday the car wouldn't start so have replaced battery (appeared to be the original!) and reset the window drop.

Complete speculation but am wondering if a failing battery might have caused electrical gremlins. I'll report back on this thread in a few weeks time if it works in case it'll help others.

[Penelope Stopit]

mikeyr said:

Update to this (thanks for suggestions all) - I've gone about 10 days without the issue reoccurring.

Don't know if this is coincidental or not but yesterday the car wouldn't start so have replaced battery (appeared to be the original!) and reset the window drop.

Complete speculation but am wondering if a failing battery might have caused electrical gremlins. I'll report back on this thread in a few weeks time if it works in case it'll help others.

No the battery wasn't causing the problem
If the problem arose and the car would not start due to a flat/faulty battery it could have been the battery causing the problem

[S0 What]

mikeyr said:

Update to this (thanks for suggestions all) - I've gone about 10 days without the issue reoccurring.

Don't know if this is coincidental or not but yesterday the car wouldn't start so have replaced battery (appeared to be the original!) and reset the window drop.

Complete speculation but am wondering if a failing battery might have caused electrical gremlins. I'll report back on this thread in a few weeks time if it works in case it'll help others.

I wouldn't put it out of the realms of possability but my first answer would be no, i see a lot of wierd issues solved with a new starter battery, for instance a focus with poor idle, changed the idle valve, cleaned all the inlet and throttle body, changed breather hoses and new sensors ect, only cured when the battery went down due to the first really cold night, changed it and the idle is now stable as a anything? and yes i did test the battery and load test it.
Merc in LOS and stuck in 2nd gear, read all the codes and cleared them time and time again, only on the 5th attempt did we get a battery voltage low code (even though the battery was showing no signs of having trouble starting the vehical), new battery = issue solved, after a LOT of research the old battery was dropping under 9.5V on cranking and that was putting the gearbox ECU into LOS, again at no time did the battery struggle to start the vehical (6Cly CDi) in fact i have used that exact same battery as a jump battery for the last 2 years.

Slightly low voltage at cranking can cause issues with one of many of the ECUs that now prevale in many modern vehicals.
Having said that your issue sounded more like the remote battery rather than the vehical battery but nowdays they are so complicated and sensative i wouldn't (as i said) put it out the realms of possability.
Also i have had issues with interferance causing remote issues, some street lamps block the signal if you park under them, wether this is normal or an issue with a failing/damaged lamp i have no idea but it has driven me mad in the past trying to solve an issue that simply isn't there when the vehical comes into the workshop, trust me it was TOTAL luck i noticed when returning the vehical that it wouldn't lock propperly outside the owners house but did once i'd gone round the block and parked it outside next doors house !
Once the usuall has been investigated and disproved then you move to the unusuall (sort of my vesion of occams razor).

Edited by S0 What on Thursday 1st December 14:40

[GreenV8S]

Reminds me of an airfield sprint a few years ago where several competitors had intermittent starting problems. Some hours into the day we realised that the problems coincided with the radar dish on the far side of the airfield pointing our way - just waiting until the beam had swept past before trying to start completely avoided the problem.

[mikeyr]

Afraid my locking issue appeared intermittently at different locations so unlikely to have been blocked (especially as the locking mechanism would activate then unlock itself). Unless the alien spaceships are following me everywhere i go...

[S0 What]

I wasn't really suggesting that was your issue just that wierd st happens
I had one aftermarket alarm remote that would not unlock the car when in a large carpark unless you stood 2 feet away, it would however lock/unlock other cars at ten times that distance, other cars with differant makes of alarm ! it was ammusing to unlock 3 other cars 20 to 40 feet away whilst refusing to open the dam car it was ment to unlock , away form other cars it would work fine at up to 30 feet away, never did get to the bottom of that one, mainly cos it was the wifes car so i just blamed her
It could be a slightly misfitted micro switch for the door ajar function, worn switch contact pad on the end of the switch arm or as i said bad soldering, if you look inside say a Mk4 golf door lock it's depressing the amount of gumf in there, even had locks continuasly cycle after a new door rubber was fitted, you wouldn't expect to have to adjust the door striker after fitting a new seal just so the C/L will work correctly (well i would now but not 8 + years ago), my sons fiesta needs the remote fob re-syncing every few months, more often in the winter, gave up trying to find the issue and taught him how to re-sync it himself
I can only think possably the use of the key forcing the lock to cycle again and again could be heating up a contact and making it more of less conductive ?
or it is the aliens do you have a large roll of tin foil to make a hat, for the car