Central Locking (using key) problem

[MJL944]

Gents,
I'm baffled by a central locking problem I've encountered today on my 1989 S2.

I've just fitted a new driver's door handle with a new lock cylinder (with internal tumblers reconfigured to match the other locks) and I refitted the old central locking micro-switch which was attached to the old handle.
The previous lock on the old handle has never worked in the 5 years of my ownership as it was seized solid presumably through lack of use so I've never had the central locking working via the driver's door. The central locking works OK via the passenger door and via the blipper/immobiliser pad.

I've now got the driver's door handle opening nicely but the central locking via the door lock is not working properly.

I'm experiencing this:
- Driver's door lock turned to right opens both doors OK - happy days!
- However, driver's door lock turned to left will lock only the driver's door but not the passenger door (main issue)
- (If I manually pull the door lock LED knob when the lock and door is closed this does open both doors)

- The passenger side lock (as always) operates like this - turn to right closes both doors; turn to left opens both doors
- However, note the different direction I have to turn the passenger lock to get an open or close when compared to driver's door - why is this? (secondary issue)



Any ideas what's going on?
- All I can think is that the micro-switch is playing up. The contact area on the switch to the handle looked clean and undamaged when I refitted it and the connection to the handle seems solid (although I couldn't really understand how the micro-switch connection area worked when I was putting it all back together).
- Also, whereas the feel of the central locking triggering on the passengers side lock seems very light and smooth the driver's side operation seems very meaty and there seems to be a fair lot of resistance when the central locking triggers to open on the driver's side but this may have something to do with a new handle. The key operation on the new door handle is lovely and light though as you'd expect. I've thoroughly greased the driver's door locking mechanism with lithium grease and watching the whole mechanism work through the door it appears that everything is moving freely.

Any advice or suggestions would be greatly appreciated as I've got the door in bits (door-card; window guide rail; window motor and door glass are all out) and I really need to get this all back together pronto.

Ta,
Mark

 

[BlackMagic]

The microswitch has a 2 switches inside (Lock and Unlock) and hence there are 3 wires - common which connects to either theh lock or unlock wire. It sounds like the unlock side works but lock doesn't. However, don't jump to assumption that it is the microswitch as broken wires (especially where they go through the door hinge) are common after 30 years.

You really need to work your way round the wiring connected to the microswitch with a multimeter (continuity tester). Start at the connector near the bottom-rear of the door (see 57-13) and if all is OK there you will have to work your way back along the loom.

See Porsche repair manual (section 57-15&16) for the procedure to troubleshoot central locking.

Good luck, you will need some patience.

William

 

[MJL944]

Thank you William. That all makes sense.
As for the 30 year old wiring through the door hinge you mention, this is timely as I've taken the opportunity with everything off the door to clean the inside of the door, fit a new door check strap and deep clean the a-pillar area behind the check strap and, despite being as careful as possible due to the possibility of brittle wiring, I know I've also disturbed the wiring in the area you mention by knocking it a bit while working around it.

I don't posses a multimeter or know how to use one but it is a skill I've been waiting to gain after seeing Edd China use them on Wheeler Dealers. Time is against me to learn now as I need to get the car door put together pronto.

Reading up on micro-switch issues just now, I've read that a quick way of identifying if the micro-switch is at fault is by disconnecting the switch at the pig-tail connection in the bottom of the door (where the micro-switch joins the loom) and to 'jump' across 2 of the 3 pins e.g. 1-2 should either unlock/lock and 1-3 should cause the reverse. If the door locks work by doing this then the micro-switch is at fault.

Does this sound correct? How do I 'jump' across the pins?

While the switch seems favourite I do understand that there may be a wiring issue elsewhere - I just hope not!

thanks,

Mark

 

[Waylander]

the simple answer is if the task is beyond you to the level that jumping connections is out of your zone then don't,

I would just buy a micro switch and fit it.

 

[MJL944]

Sensible advice Waylander but, despite my limited skills, and emboldened by my recent not inconsiderable feat of having removed and refitted both door handles, I did have another stab at this today with some progress which was followed by further bafflement............

Progress: Having asked my nearby garage what 'jumping the pins' equates to I armed myself with a straightened paper-clip and put one end of the wire in the female pin on the pigtail connector for the micro-switch on the driver's side and touched the other end to each of the 2 male pins separately and, hey presto, both doors lock and unlock - good, it appears there's no problem with the loom wiring and it looks therefore that the driver's micro-switch is dead. New switch ordered from OPC Nottingham at £75 all in but seems a safer option than a used part seeing as how often these switches cause central locking issues.
Of course, it could still be that it's the connection from the new handle to the switch that is somehow the problem - hope not.
I did contact clean the pig-tail pins on both sides and tighten the screw at the back of the door lock cylinder on the handle but neither solved my problem.

Further bafflement: I'd left the micro-switch disconnected from the pigtail connection to the loom at the bottom of the driver's door and tried the key in the driver's lock and to my confusion found that the lock behaves the same as I reported before i.e. it will unlock both doors when turned right but will only lock the driver's door when turned left.
So, whereas before I thought my driver's door micro-switch was operating the central locking on the unlock cycle but not the lock cycle, it turns out it is doing neither. This explains why the feeling of the central locking unlocking via the driver's door feels so 'meaty' as I described it before - as if it's not assisted by the microswitch working correctly.

Q: Why/how is the driver's side lock closing the passenger door lock when the driver's microswitch is disconnected? Is this normal?

Thanks for any suggestions and advice.

 

[BlackMagic]

Hi Mark

You really are delving into the workings now.

Looking at the wiring diagram


944 door lock electrics.JPG

it looks as though there are 2 triggers for the locking mechanism (1 - using the key when you turn the lock; 2 - an internal connection in the lock actuator - which I presume works when you lift the button inside the door). Hence, without the microswitch working you have to move the whole lock manually, but when you do the 2nd switch in the lock actuator kicks in and opens the other door. I have no idea whether it should work in both directions but I suspect when you get the new microswitch it won't matter!

Onwards and upwards

William

 

[John Setchell]

Don’t know if this is relevant to this thread, but my newly acquired 2000 986 would half-drop driver’s window sometimes when shutting door. I was dreading taking off door card and trying to identify a sensor fault or whatever. Then it occurred to me that when the slightly dropped window wound-up after closing the door it thought something was trapped in it and opened as programmed. Eureka! - clean/lube rubber seal around window top with silicone spray and problem solved.