AWR-fix: Door Lock Actuator Repair

[andrewwynn]

First things first: credit where due; Thanks to @oldskewel for getting the ball rolling on this repair; I didn't want to make a car inoperable to take out an actuator for learning, especially in case i destroyed it, I also didn't want to buy a used one for $50 that would also need the same repair done, again just for learning. To see many more photos of the internal workings of the lock mechanism visit the original repair thread here



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I fixed my wife's 3rd of 4 door actuators today (one more to go). I took detailed photos so I could share and other people can stop spending $100s to replace a $6 motor.



All four of wife's door actuators failed one after the other within about 8 months. Coincidence that her car has automatic lock enabled at about 4mph? Not a chance! Wife's car goes through 2-3x as many lock cycles as my car because of the automatic locking!



Four actuators would be between $600 and $920 at Amazon prices! I've spent $24 so far and will spend another $12 for two more motors: now that I've got the procedure down it only makes sense to replace both primary and secondary lock motors when doing the fix. 96% discount; not bad.







Here's a preview of the actuator just after separation from the latch assembly.







Here's the actuator opened up to show the two motors. The angled one is the double lock motor, the horizontal one is the one most likely to have failed and is the lock motor.



In addition to replacing the door lock motor, I upgraded the latch to be freeze resistant.



I discovered the root cause of all cold weather door handle carrier destruction and created a solution which I will also cover here.



Here is a preview:





The problem is that condensation will form on the latch on a particular joint where a rivet actually touches the bracket that holds it. Look at the photo above; see the shiny spot that is water.



I'm going to post the step by step with captions to my iCloud photos. Tap on a photo to see it full size, tap again to turn captions on/off.



https://www.icloud.com/sharedalbum/#B0SGsCn7Ga0oFm



Just like the design flaw with the siphon jet o-ring, the flaw in the design that kills the door handle carrier is actually the actuator in most cases.



I was completely stunned when I took apart my wife's right front door to fix the actuator motor and by complete coincidence, it was crazy cold outside and was recently above freezing and rainy so even after I brought the car in the garage and even after I removed the actuator it was still frozen solid!



After discovering where the failure point is, I did some testing with drops of water and putting the latch in the freezer. I did about 5 freeze tests and came up with a great solution that is very easy for people to replicate.







Here is a preview of the frost free fix. I applied some low friction material that has double stick tape and then put low temp grease on that too help repel water in the first place.



I put as much water as I could get to stick around the joint and put it in the freezer for almost two hours. After removing I could not even feel the resistance from the ice much less have it stick.



In the first tests, I could not break the joint free by hand, it was quite clear that was the actual source of frozen door handles.



I did some experimenting with the door handle carrier as well and replicated the failure mode and again it is quite clear the problem is when the latch is frozen, the cable will not move and the stress is put on the hinge and causes it to break.



BMW incorrectly determined the porblem was water getting in the cable and redesigned the cable to attempt to eliminate water getting into the cable, but as we all know it didn't help, well now we know why: the latch freezes not the cable : the stuck cable is a symptom not the problem



I developed a method tonight to repair that type of DHC (door handle carrier) failure using a single stainless steel zip tie (28¢). I will be making a separate thread on how to repair a DHC.







Quick preview of that repair. It took hours to figure out a solution that can put up with the abuse of pulling on a frozen latch. It was amazing to see the hinge pull itself right apart in spite of a very solid repair.



In the end, tweaking the stainless zip tie so I could make it go around twice was the winning solution! It's so simple and elegant. It only takes a few minutes to perform the fix, and it's quite a lot stronger than originally designed so I recommend adding the steel zip tie to any NEW DHC as well so it will prevent the failure from ever happening again.

[mike325ci]

Brilliant fix for the frozen latch.

Do you replace the entire motor or clean out the commutator? What's the part # on the motors?

DHC fix / reinforcement also brilliant. I'm about to replace the two front ones on my 4.6is I just bought. I have replaced them before and they all break at that point due to thin cast metal taking a lot of force. You just wrap the zip tie twice around that and presto?

Thanks for the work and experimentation!!

Sent from my SM-N950U using Tapatalk

[andrewwynn]

@ Mike: I have to buy two new motors. I only take the end off of the motor since you can't buy complete motors with a long enough shaft and I'll update the first post with an Amazon link when I figure out which item.

There are a couple tricks to get the metal strap to fit in the tight space and to get it through twice and tighten the ever lovin' crap out of the thing.

4 Pack - 20mm Round Shaft Central Door Lock Actuator Motor FC-280PC-22125, Spindle, Power Locking Repair Engine https://a.co/d/aFYQzQJ

These were the motors I bought. I can't remember if the shaft was long enough to use the whole motor. I just transplanted the brush end of the motor.

[oldskewel]

Great stuff! Thanks for figuring it all out so carefully.

On this point ...

Originally Posted by andrewwynn

...All four of wife's door actuators failed one after the other within about 8 months. Coincidence that her car has automatic lock enabled at about 4mph? Not a chance! Wife's car goes through 2-3x as many lock cycles as my car because of the automatic locking!...

Would a helpful and easy setting change be to set the unlocking to only unlock the driver's door, rather than all 4 (which would then require a second press to unlock)? I think that may be the default setting, but many people change it so all 4 unlock on the first press, just for convenience on the occasions that they do need more than the driver's door unlocked.

So then leaving the automatic lock enabled could be done without compromising safety.

[andrewwynn]

That's an interesting point, however it seems more often than not, a second door is used to toss in a bag etc. so even though in Lita's case, with first press driver only, she more often than not double-presses to open a second door/trunk/boot/back/hatch/emergency entrance (never know what to call a non-trunk). (of course not a lot of good that did her with 3 of four doors not unlocking and 2 of four doors not locking); down to just ONE remaining now though ! (and all the tedious engineering out of the way so it'll be fast)

Not exactly sure what safety is compromised; against car jacking? you can always manually lock when you are in stop n go in the city, but in our case where 95% of trips are point-to-point with no in-city stops (where a person could ever come up to your car), there really is no need to lock your car door while driving. For people with kids in the back, that's what child safety locks are for; no egress from inside handle.

[itscoo2pyopants]

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