Forgive me if this is answered elsewhere -- I searched but didn't find anything that seemed to match my situation. If there is a discussion I would be grateful for a link to the thread.

'04 MCS, 190k mi, purchased new in Mar '04.

A few weeks ago the PS door lock stopped answering requests from the central locking to unlock. Lock works fine from the fob, the toggle, or when speed-activated. DS door, tailgate, and fuel filler lock and unlock normally. The PS door unlocks normally from the interior handle (i.e. first pull unlocks, second opens).

Last Monday I removed the actuator to inspect it and when testing it in my hand connect to the car's wiring, there was one motor that was working but the second did not. Ok, 190k mi, things fail. So I went to the dealer and plopped down $220 for a new one. After I installed it, it worked fine. Score! Miller time.....

Today however the new one is behaving exactly the same as the original. Lock works fine, unlock does not actuate. While it's possible I suppose that the brand new one has developed the same fault as the original, I would think it extremely unlikely. Suggestions?

Thanks!

 

It’s possible the new lock is also bad, but seems unlikely as you stated. Most MINI parts have a 2 year warranty on them, but I’m not sure if it is different because it’s an electrical part so I would check with the dealer if it is bad.

A few of other things to check would be the lock module wiring and plug contacts to make sure they’re not broken or dirty, the BCM which controls many of the electrical functions for the car, and the battery. The BCM is in the passenger kick panel area of the car and if you have a sunroof, the drain tubes often come loose and drips water right onto it which shorts it out or corrodes the connector.

Also, MINI’s can really act up with voltage fluctuations and issues many have be solved with a new battery, even if the old battery seems to be working fine and not having any issues with cranking or starting. How old is your current battery?

The door lock issue isn’t uncommon and there are some DIY’s posted on repairing the modules. Here’s one: https://www.northamericanmotoring.co...placement.html

 

Thanks!
I didn't notice any damage to the wiring or plug when I replaced the actuator, but I didn't minutely scrutinize them either. Perhaps worth a look.

The car doesn't have a sunroof (we specifically bought without because they inevitably leak ) so I think the BCM should be dry. But worth inspecting.

I can't recall when I last put a battery in it. So I'm going to go out on a limb and say "battery is old." Sounds like that might be the place to start. I hadn't considered the battery because, as you say, I've had no issues with cranking or starting.

My gut feel is that this new actuator is fine, and the old one may be as well. Not that I'm going to reinstall it!

 

Hopefully the problem is something simple and a new battery solves the problem.

The DIY might still be good for re-building the old module as a spare, or rebuilding the drivers side if that start acting up. I would keep the old module around for parts or to practice on.

 

Getting back to this...

Battery is 8 years old so it may well have subtle issues even though it's not displaying overt problems. And the car sitting for long stretches due to covid making me work from home doesn't help. The battery is on charge at the moment and I cleaned the connectors for good measure, not that they appeared to need it.

After reconnecting the battery and allowing it to charge a while, nothing has changed.

I looked through this 400-post thread and saw my issue over and over and the answer was always the same -- new actuator. I just still find it really curious that the new one would fail the same way in a week, esp given the car is hardly used.


What I have been unable to find is a pinout of the connector to the actuator. By trial and error on the old one I've found that pins 7 & 8 operate the working motor. No other pin combos will work the other motor so I suspect it really is bad. But I'd like to be able to test the new one without fear of damaging it (especially if I end up returning it under warranty). Does anyone have a pinout?

I also found a reference to resetting the ECU to be a potential fix. On another site I found instructions on how to do so by accessing the diagnostic functions of the instrument cluster. But at the bottom of the page there is a parenthetical that says this reset function does the same as disconnecting the battery (which I've already done). Is that in fact the case? If so, I don't need to bother trying the reset.....

Thanks!

 

Answering my own question: Let's call the "upward-pointing" motor, motor1, and the "inward-pointing" motor, motor2. Motor1 is on pins 4 and 7, and motor2 is on pins 8 and 7. Direction of operation is controlled by polarity -- reversing the polarity reverses the motor. (Aside: my motor1 was stuck. I rotated it a little to break it free and afterward it runs with voltage applied although it noticeably smokes!)

The new actuator now neither locks nor unlocks. 🤬

The

 

And the car just made me a liar. It just locked (still won't unlock). I'm thinking it's not the actuator....

 

I guess I'm blogging the diag & repair here.....

I've confirmed signal on pins 4 & 7 of the harness plug (disconnected). When subsequently plugged in, the actuator will lock and unlock the door. This tends to confirm to me that the fault is not in the new actuator. (Although as stated above the old one did have a fault). I wonder if the frozen motor in the old one might have stressed the component(s) in the body controller enough to cause an intermittent fault.....

EDIT: Everything's reassembled. Now we wait....

 

Possibly broken wires in the door jamb from all of the opening/closing throughout the years causing intermittent connections?

Had this happen on another car. Apparently it was so common the manufacturer had a repair kit with a partial door harness to splice in by the rocker panel with special solder enclosed heat shrink connectors.

Although, my ‘05 with only 50K has had the same issue with not unlocking for the last few years so the door has gone through a lot less cycles than yours. I’ve had a new lock to install for a few years now but haven’t made time for it since it’s not driven that often. Hopefully the new lock is the fix, and the old lock can be repaired for a backup.

 

Certainly a possibility! That's the next thing I'll check....

 

Forgot about this thread. I hate when I'm searching for a problem online and find plenty of similar questions but never the resolution!

After my last post I did more diag on it but found nothing definitive. Once reassembled it worked normally and has continued to do so. Maybe it was as simple as a dodgy connection. We'll probably never know.

The battery failed in Jan 2022.