If Central Locking System Fails, How Do Locks Work?

[shertex]

On my 92 300D, I have a vacuum leak in the central locking system, the result being that the pump operates for 33 seconds before shutting off when I lock or unlock the doors.

I intend to get it fixed (but can't for a couple of weeks), but I am curious....if the pump were to fail, how would the locking/unlocking work? I assume that the key would continue to operate the driver door and the trunk and that the other three locks would have to be operated manually. Is that correct?

Thanks.

[JHZR2]

That is a good point. On my w123 cars, the lock/unlock on the passenger side goes up/down flawlessly with vacuum. It will unlock with the key, but it will not relock by hand or with the key. Ive tried pushing HARD.

[babymog]

Without the pump, the car will lock manually with the buttons or with the keylock where equipped.

The exception will be the filler flap, which would need to be locked manually at the actuator behind the trunk liner.

[vstech]

on the 123 with a working system it's hard to manually lock the doors... but if it's damaged, then it's easy to manually lock/unlock them

[bobodaclown]

Yes. They work manually. The fuel door might be a bugger. I don't remember how easy it's to get to in the trunk. Keep you tank full. LOL

[Mark DiSilvestro]

On both my 240Ds, I've disconnected and plugged the lock's vacuum supply, as a leak was preventing engine-shut-off.
But it became a pain to manually lock or unlock the front passenger and both rear doors, as the lock-buttons were constantly fighting against resistance in the vacuum-pods.
On one 240D, I had to pull those three door-panels anyway, to replace broken door-checks. So while I was in there, I disconnected the vacuum-pod rods. Now the manual door-locks work nice and easy on that car.
On both cars, the fuel-flaps stayed unlocked, but both trunks remained locked, and need the key to open.

Happy Motoring, Mark

[bobodaclown]

Originally Posted by Mark DiSilvestro

On both my 240Ds, I've disconnected and plugged the lock's vacuum supply, as a leak was preventing engine-shut-off.

Not applicable on the W124 300D. Separate pump under back seat that does doors, trunk and fueling door.

[compu_85]

And unlike the early cars it is a bi pressure system, the pump in the rear can do both vacuum and pressure. Vacuum locks, pressure unlocks. That can lead to a situation like my car, where one activator has a pinhole leak, so it will unlock but not lock.

-J