Door lock question

[strupgolf]

Car: 1989 944 S2. When I put the key into the door to lock it, the knob goes down but then comes right back up. I can lock the pass. side door by just pushing down the knob and it stays. What's up with these door locks where I cant lock the car up. The manual does not seem to help, or maybe I'm missing something. Any thoughts?

[PorscheChef]

Do you have power locks? I have an 87 951 with the same problem. I think it has something to do with the power locks. Sorry I don't have an answer, just wondering if it may be the same.

[sjv]

my 88 N/A has the same problem right side door locks both doors driver's side won't work

[Phantoms]

I guess this is pretty common. The same exact thing happens on my 90 S2, as well as on my friend's 86 911.

[Shifter]

If the central lock computer thinks the drivers door is open, it won't allow the door to lock. What happens if you press the lock button on the center console? Key has to be in the on position for it to work.

Using the key on either door should lock or unlock both doors.

Last time I saw this, one of the signal wires had broken in the insulation at the door hinge. Ran a new wire, and the locks have been happy since.

[Libegar]

I believe I read in my owners manual that the reason this was implemented was so that you could not accidentally lock your keys in your car. It forces you to use the key to get out of the drivers door...Page 12

Doors
To lock, unlock and open doors from the outside
All doors can be locked with the ignition key.
The passenger door can be locked without a key by first depressing the locking knob and then closing the door.
The driver's door can only be locked from the outside with the key. This precaution was taken to prevent locking the driver's door while the key is still inside the car.
Squeeze trigger in door handle to open door.

[Libegar]

Correction, I miss read, sorry though it was a different scenario

[Phantoms]

I have an update on this issue. While fixing my non-starting S2 due to an alarm malfunction I inadvertently solved my drivers side door lock woes. (Mine were exactly as described by the OP)
Long story short:
Battery box was leaking- Repaired it. Found that the Alarm Control Unit part # 928 637 104 05 was completely filled with water. This is located behind the DME unit in the passengers foot well. I swapped the ACU out for a fresh one from a wrecked 89' S2 Cabrio and my car started up like a charm. A few days later when I replaced fuse #8 that I had removed during my original alarm malfunction (controls central locking and alarm horn) my drivers side lock was working like new again.

I'm assuming that before the H20 completely destroyed my ACU it only mucked up a part to do with the drivers side door lock? Or maybe the part of the ACU controlling this lock gave out on its own before the water showed up? Regardless, at least now we have a possible idea for the root cause of this issue on the S2 at least. I'm not sure if earlier cars have the alarm control unit in the same spot.