Door Locks - How should they function?
 

sorry for another door lock thread. I simply don't know exactly what to expect the locks to do while im fixing them (fixing them is so well covered - thanks everyone).

- When I lock using vacuum, can I still operate them manually?
- How do the manual and vacuum lock functions interact? when does one overide the other?
-When manually locking, should the locks clunk up and down securely, or do they just move the same 3/4" they do when locking with vacuum.

Thanks - I just need a primer on how they should work...hopefully this can help other folks too.

dd

Diff'rent strokes...
 

It depends on the model year...

Your car and my '85 should be similar. My wife's '87 is somewhat different.

Basically, operating the locks "manually" or by "vacuum" is the same thing. When you operate the lock on the driver's door, whether by using the key from the outside or with the knob from inside, you are activating a vacuum switch. This causes vacuum from the reservoir in the trunk (of a sedan or coupe, don't know where it is in a wagon) to go to all of the door locks, the trunk lock, and the gas flap lock, and lock or unlock all of them.

(I'm describing it backwards, of course: vacuum doesn't "go" anywhere. Air from the various locks is pulled through the tubing and valves to the vacuum reservoir, thus making the locks work. You knew that. :D )

If you operate the passenger door lock with the key from the outside, only the passenger door unlocks. Ditto for the trunk. For later cars, like my wife's '87, these locks also unlock everything else. This may also be true for earlier 300SD models (126) -- I don't know.

I'm not sure about correct operation of the rear seat locks. Sometimes mine won't unlock manually from the rear seats. I suspect that I may have a vacuum leak in the driver's door vacuum switch. Like you, I need more information -- how did they work when they were brand new?

Jeremy

Jeremy - agreed, we both just need to know how they worked in the first place.

Anyone?

I don't believe the rear door locks a designed to be unlocked manually if the drivers door is locked. I believe mine work correctly, and they will not unlock manually from the back. I assume this is a "child lock" feature.

I just tested my '85. With the driver's door (and therefore all doors) locked from the inside, I can lock and unlock the rear doors by pushing/pulling on the buttons. One has to push and pull with some enthusiasm and the locks make a solid mechanical 'pop' sound but they do go down and up.

My factory original owner's manual says that the rear door locks can be operated manually. However, it also says the rear doors cannot be opened until the locks are unlocked. I think this is the "safety" feature you mentioned. (You'll remember that the front doors can be opened from the inside and, if locked, then automatically unlock. Opening the driver's door, of course, then unlocks all of the doors.)

It IS a good thing you added that clarification, or somebody that wants to show everyone how smart they are would be splitting that hair......

stretch=elongation
algae = fungus
gas mileage=fuel mileage
push the throttle=push the accelerator

We all know most of these sticklers.....:rolleyes: [we love 'em, but we know 'em]

That's different from my 82, on mine the rear door locks would not unlock unless I pulled hard enough to overpower the vacuum, which I've never tried to do.

This seems to be the case in mine too. Thanks for the info -I guess I need to find an 82 owners manual.

I'll take a look in the owners manual when I get a chance too. It's possible that they should unlock manually and something needs to be lubricated. I always unlock the drivers door if someone needs to open the back door.

Well, I was wrong. :o I just tried my locks again and discovered that I can manually unlock my back doors with the drivers door locked. It took a little extra force, but they do unlock with a little click (just like the passengers door). They got easier to unlock after I cycled them a couple of times. However, the back doors will not open from the inside unless they are unlocked first (unlike the passengers door). Sorry for the confusion.