central locking problem....

[Jinster]

I have posted the same thread on 986forum but nobody there seems to have any suggestions. I am hoping someone here can give some pointers.

I have had this problem for a while now. I will try to describe this in detail. The car is a 97 Tip without alarm or remote modules.

Initially - and I don't know if this is related - the driver's side window will not stay slightly lowered after the door opens. But pulling on the door handle both inside or out does lower it so I have been pulling on the door handle to lower the window to close the door to avoid hitting the window against the top frame for a few months. That problem is gone spontaneously now. And at about the same time, the new problem started:

Driver's side:

I can't lock the doors from the driver's side.

If I try turning the key once on the driver's side, the doors (including the fuel door) would lock, and then all three doors would automatically unlock straight away within the same mechanical sequence (I hear the mechanism's locking sounds, straight away followed by unlocking sounds).

If I try to emergency lock on the driver's side by turning the key three times, the driver's side and the fuel door would stay locked, but the passenger side is not locked at all. Also, the doors can be opened from the interior door handle if locked with the triple turn like this (I don't know if this point normal, never did it when the car was working fine).

Passenger's side:

If I try to single turn lock from the passenger's side, all three doors would lock and then straight away unlock much like if I tried to lock from the driver's side.

I can, however, lock all three doors successfully if I emergency triple turn lock on the passenger side. If locked this way, I can unlock all three doors normally from the passenger's side. But if I unlock from the driver's side, the passenger door would stay locked from the outside and the central locking switch light would stay lit as I drive the car. The passenger door can be unlocked via the interior handle.

I am completely baffled. I need some thoughts as to the logic of what is happening. I can't think of a sensor or actuator failure that could single-handedly lead to such symptoms...

What exactly is emergency lock anyway? I assume it was designed to bypass some circuits or mechanism which may be faulty to make locking possible in an emergency situation in case of component failure. But what exactly is bypassed?

Also, the fact emergency lock works on the passenger side would seem to suggest that the actuators on boths sides are working properly (unless emergency lock doesn't actually use actuators?).

The fact that emergency lock on driver's side doesn't work may suggest some sort of one-way communication failure between the driver's side and passenger's side, but what could that be?

I think it may well come down to the mechanism that'is actually involved in emergency locking. Part of it may have failed. If you guesstimate the emergency lock to be a "skeleton system", the most basic system, the simplest electromechanical pathway to lock the doors then this would account for the higher functions of normal single turn lock not working on both sides too. The question then remains, which electromechanical parts are actually involved in the emergency lock pathway?

Anyone have any thoughts on the situation at all?

I plan on opening up the doors to have a lock, but it would help if I know where I should be looking at.

[Richard Hamilton]

I had a very similar problem with my 996, which turned out to be a bad microswitch in the door lock assembly on the driver's side. The 996 only has a lock on the driver's side by the way, so I couldn't tell you what happened at the passenger door!

A fault like this should flag up a fault code in the C/L control module, which would be shown in a PST2 test. There are 5 microswitches in the door lock, and two in the handle. I would say that the handle switches are working OK from what you have described, which leaves the door lock switches. If you have access to a PST2 I would get it checked out first.

I think you might want to look at the system from a different angle. The key operates the lock signal switch - the alarm control module powers the motor to lock the door - the locking mechamism triggers the 'locked' microswitch - the control module takes power off the motor. If the control module doesn't get the 'locked' signal it thinks something is wrong, so unlocks. The emergency locking signal to the control module is three pulses from the lock signal switch. This will power the lock motor regardless of the other input signals.

Edited March 3, 2007 by Richard Hamilton

[Glyn]

I have posted the same thread on 986forum but nobody there seems to have any suggestions. I am hoping someone here can give some pointers.

I have had this problem for a while now. I will try to describe this in detail. The car is a 97 Tip without alarm or remote modules.

Initially - and I don't know if this is related - the driver's side window will not stay slightly lowered after the door opens. But pulling on the door handle both inside or out does lower it so I have been pulling on the door handle to lower the window to close the door to avoid hitting the window against the top frame for a few months. That problem is gone spontaneously now. And at about the same time, the new problem started:

Driver's side:

I can't lock the doors from the driver's side.

If I try turning the key once on the driver's side, the doors (including the fuel door) would lock, and then all three doors would automatically unlock straight away within the same mechanical sequence (I hear the mechanism's locking sounds, straight away followed by unlocking sounds).

If I try to emergency lock on the driver's side by turning the key three times, the driver's side and the fuel door would stay locked, but the passenger side is not locked at all. Also, the doors can be opened from the interior door handle if locked with the triple turn like this (I don't know if this point normal, never did it when the car was working fine).

Passenger's side:

If I try to single turn lock from the passenger's side, all three doors would lock and then straight away unlock much like if I tried to lock from the driver's side.

I can, however, lock all three doors successfully if I emergency triple turn lock on the passenger side. If locked this way, I can unlock all three doors normally from the passenger's side. But if I unlock from the driver's side, the passenger door would stay locked from the outside and the central locking switch light would stay lit as I drive the car. The passenger door can be unlocked via the interior handle.

I am completely baffled. I need some thoughts as to the logic of what is happening. I can't think of a sensor or actuator failure that could single-handedly lead to such symptoms...

What exactly is emergency lock anyway? I assume it was designed to bypass some circuits or mechanism which may be faulty to make locking possible in an emergency situation in case of component failure. But what exactly is bypassed?

Also, the fact emergency lock works on the passenger side would seem to suggest that the actuators on boths sides are working properly (unless emergency lock doesn't actually use actuators?).

The fact that emergency lock on driver's side doesn't work may suggest some sort of one-way communication failure between the driver's side and passenger's side, but what could that be?

I think it may well come down to the mechanism that'is actually involved in emergency locking. Part of it may have failed. If you guesstimate the emergency lock to be a "skeleton system", the most basic system, the simplest electromechanical pathway to lock the doors then this would account for the higher functions of normal single turn lock not working on both sides too. The question then remains, which electromechanical parts are actually involved in the emergency lock pathway?

Anyone have any thoughts on the situation at all?

I plan on opening up the doors to have a lock, but it would help if I know where I should be looking at.

This sounds very much like the passenger door lock mechanism as you can emergency lock, otherwise you hear the locks acutuate then unlock.

There are a series of mocro switches within the mechanical lock, officially they are unserviceable but it is possible to strip the lock down and get to the micro switch, the use a screwdriver to close the lock and a bit of wire across the microswitch terminals, then try the lock procedure, the car should then report everything is locked.

The window dropping thing is another micro switch fixed just above the exterior handle (within the door) it is held in place by two plastic push in lugs, they often become detached, As you pull the handle to open the door the micro switch is released and the window drops.

Very easy to check, remove the door card and look just above the lock mechanism where the door handle assembly is, operate the microswitch manually or again use the wire to make and break the contact, Replacement is dead easy.

Glyn

[Jinster]

Thank you both very much. I will look into this in the next few days and report on my progress. At the moment, I need to:

1. Replace a leaking coolant pump (planned on Monday)

2. Trouble shoot my stuck top in up position (planning to do tomorrow)

3. Open up the door panel to look at the central locking situation, microswitches sounds culprible. (maybe Tuesday)

It's a good thing I got some time off work.

Are the microswitches individually replaceable or do you just buy the whole locking mechanism from Porsche?

[Richard Hamilton]

I replaced the whole switch, but Glyn says you can strip it down.