I wanted to post this because I searched and found only 1 post that seemed similar to my problem on this entire website.
Hopefully a search will find this thread for the next person who cannot get into the car.

Recently my driver’s side door failed to open about 50% of the time. it seems each time I attempted to try pressing the button to get out or get in using the outside pad the motor that releases the latch got weaker and weaker to the point it would not do anything but index the window in preparation for the door to open.

After doing some electrical troubleshooting I determined that the motor in the latch itself must be overheating with each press of the button. As power was present for about .5 second with each press of the release button.

I ordered a new latch for gmpartshouse.com at a cost of 130.00 and it solved the problem.

I took apart the old latch to examine the actual problem. I found the mechanism to be pretty simple with a motor driving a plastic gear and return spring to reset the latch after it opens.

I took the motor out and using a 12 volt power supply found the motor works just fine until you put a load on it. If you attempt to stop the motor it will reduce its rotational speed to a crawl and had literally no power but will continue to spin very slow, so slow that you could almost count the rotations.

If anyone from GM is reading this board I post this because it may help to redesign the part to make it better.

I can say the motor doesn’t show any signs of heat when this happens. It simply runs slow and with not much power. I found that if I reverse polarity it runs normally or if I let it sit for a while it will run in the same direction as before until it is loaded again.

I have come to the assumption that the armature magnets get saturated and stay magnetized. It is definitely not getting hot and the brushes after taking apart and cleaned don’t have any effect.

I cannot think of any reason why reversing the polarity of the motor would cause it to operate normally again.

Anyway, if anyone has a similar problem I recommend replacing the latch mechanism.

I also cleaned the touch pads on both doors and I find they do open more easily and on the first try every time now.

Adding search terms, door will not open, won't open, latch does not work, will not release. Door stuck shut.
That should cover it.

Maybe a mod wants to make this a sticky?

 

Goood info. Should be added to RRVETTES FAQ Sticky.

 

Thanks for the info. But the door latch failure does not seem like a pervasive problem across the forum and your magnet theory would imply it should be. I wonder if you just have shorted windings as an infant mortality failure from a mfg flaw (vs. a design flaw).

 

Thanks for the info. This does and hads happen to a lot of electrical
components but few persons find out the real reason for their failure.
They usually just throw them away. Thanks I appreciated the reasons
you found for the failure.

 

I thought the same thing, however a shorted winding would cause a high current, and the motor would generate more heat. it also would be that way all the time.

I have a pretty extensive background in electronics and have even built a few motors as projects. heat will definitly reduce the output of a motor as the internal resistance of the windings will increase. however since I have little heat, no poor connections that I could find no shorting. I can only come to the conclusion that it has somthing to do with magnets. I have never seen a perminant magnet go bad, knowing how they are made it doesnt seem possible. but I guess it could happen motors are pretty simple.

I do know that when this happens the motor doesnt have the usual step/ step/ step rotation they usually have as the armature is turned through the magnetic field. which leads me to believe the ceramic magnets are faulty, or the armature magnets are saturated.

 

Thanks. I hope I won't need it, but it's good to know.
It might be helpful to add the part number of the replacement latch.

 

very nice info. it may not happen every day to every car, but I've read about people replacing latches here just about every month, so to me, it is not uncommon.

 

What is the latch part number. I have experienced the same problem on my '06 convertible. The past month the driver's door, after the car sits overnight, will not open. If i'm lucky, it will open after multiple tries. In addition, I found the trunk will not open until the driver's door opens!! If you can, pls reply to my direct e-mail address: "legalgus@tampabay.rr.com"
Thanks.

 

sorry i dont recall the part number, but your local GM dealer can look it up for you.
or call gmpartshouse.com i ordered from them

 

Car/fob just over 5 years old. Decided to take simple way out first - replace fob battery. Lo and behold, problem fixed. Door opens on first try.

 

I had the same issue and cleaned the contacts inside the switch, very dirty. Works well now. If I have trouble again I'll take your advice. Thanks.

 

I am now having a similar problem with my 2008 C6 driver door in that it opens less than 50% of the time, although the window indexes correctly.
Appears that the motor in the latch is failing, as previously described in this thread.
My problem is I am not sure how to access the latch to remove it since when I started to unscrew the latch it appears that it would fall into the fender, so how do I get to the latch once I unscrew the 2x screws on the door jamb?
I do not have a shop manual so if anyone can walk me thru this I would appreciate it.

 

George De started a new thread with his question (Post #12 in this thread) (c6-tech-performance/2888482-how-do-you-remove-driver-side-door-latch-locking-mechanism.html) and I've posted a comment on that topic. Ultimately, though, both he and I are interested in getting at the door latch mechanism.

Rather than purchase a new door latch (door lock) mechanism, I wanted to see if cleaning would help, having ruled out bad switches (inside & outside) and knowing that my window responded to the switches. So I took out the door lock, turned it over onto its head, and sprayed some dry lube into any opening that looked like it would drain into the top ("head") of the door lock, hoping that the spray solution would flow into any sticky mechanism (or at least clean it). The most noticeable opening is one towards the back of the latch since it has a red strip of plastic.

I did this a week ago and so far the lock's worked fine (unlike previous lube attempts). The electrical portion is in the upper portion of the lock while the lower portion has a separate lever based release mechanism (for the manual cable releases). I didn't open the unit up but I would have thought the electrical mechanism would be more solenoid based than motor so bass mechanic's description is interesting. I wonder, however, if the apparent low-torque in the motor is by design since all it has to do is trip the release mechanism. Too much torque would risk stripping the gear or wearing the teeth out over time. Examining a brand new or fully functioning door latch unit to see if it exhibits the same load behavior would be a useful next step.