Menu toggle

Central locking

L

lizandgerrt@tiscali.co.uk

PCGB Member
Member
Hi,
I've got an '89 Carrera Supersport Cabrio, which I've owned for the last twelve years.
I like to try a fair bit of the maintenance my self but one thing is beating me at present and I wonder whether any other owner has had the same problem and might be able to offer some advice.
The remote locking with the key fob has long gone west, so I rely on the key to operate the central locking. Lately I've noticed that when locking the vehicle, it locks, only for it to unlock again straight away even though I hold the key in the locking position.
I've taken off the door cards on both sides and removed the micro-switches behind the locks and the locking actuators. I have run a meter over each of these components and all seem to be OK. I've even managed to get hold of another ECU for the locking system but still no luck.
Has anyone else had a similar problem and found a solution? I'd be extremely grateful for a bit of advice to get things working again.
Regards Gerrt

 
I would suspect the driver's side microswitch. From memory it has three pins - a common and a left and a right. With no key being turned there should not be continuity between the common and the left or the right. With the key turned one way one pin should have continuity but not the other and with the key turned the other way the continuity should be on the other pin. At no point should you have continuity on both pins. I'm guessing this is what's happening and as a fail safe the ECU is unlocking the car.

 
Hi,

Thanks for your advice and sorry for not getting back sooner, but I had to wait for Porsche to come back with a new micro-switch.

Unfortunately it hasn't made any difference. The car still locks and then unlocks straight away.

I've unmounted both actuators from inside the door and disconnected the connecting rods so there is no load on either of them as I thought that maybe something had got tight in there and was overloading the actuators, but still no luck. One thing I've noticed is if I sit in the car and lock the doors by using the button on the centre console the doors lock and hold locked. However, I then have to unlock the drivers door manually from inside and use the key to unlock the car.

I've noticed that when locking the doors, using the key on either side, that when I lock it, turning the key anti-clockwise, that it locks and unlocks. If, however, I try using the key to unlock by turning the key clockwise it does nothing, although when using a meter on the cables from the micro-switches I get a continuity. It seems that the signal is not getting from the door locks to the ECU, although it is getting through from the centre button in the console. Any ideas?

Regards Gez

 
Hi 911 Targa,

I'm interested to learn more about the relay you mention. Could you be more specific about the position of the relay that caused your problem?

Regards

 
Hmm, sorry the new switch didn't cure the issue. It sounds like you might have a wiring issue. Let me see if I can scan the central locking wiring diagram for an 89 so that you can check the wiring continuity.

And am I correct in thinking the you can't lock the car with the key from either side?

You mention a remote - presumably for the alarm? This would not have been factory fit so if it's acting up that could rather queer the pitch.

I suspect what's being referred to as a relay and as an ECU is actually one and the same - it's more of an ECU as it contains some logic circuitry.

 
Hi IndischRot,

Sorry to be a pain.

You are correct in your assumption that I cannot lock the car from either side. I was thinking if it was only one side then the locking/latch mechanism on the driver's side door handle may be at fault.

I only mentioned the remote in the key fob that was supplied with the car, but which I have never used, only ever locking the car with the key.

If there is some confusion with the other member mentioning the relay/ECU, I have already changed the ECU behind the dashboard. It is fixed to the inside of the inner wing by a nut and washer. After I replaced the original one it didn't make any difference to the locking. An expensive example of the process of elimination.

I've received the wiring diagram you have kindly send and will attempt to decipher it again tomorrow.

Thanks again for your help.

Regards Gez

 
Good luck! If that diagram isn't crisp enough send my your email address via a message and I'll send you the original image file.

And forgot to ask the standard question - was anything else work on or changed on the car in the run-up to this fault appearing?

 
Hi IndischRot,

The diagram is fine. I've printed out twice size and have made a start wading through it.

In answer to your second question, the only I have changed is the battery. I had thought that maybe one of the old alarms had dropped in after the interruption in the voltage but now I don't think so.

Thanks again for all your help. I'll let you know how I get on.

Regards

 
My 88 3.2 had an alarm fitted and it started to play up so I removed it. It was ridiculously easy to remove. And not that I had central locking issues but it was connected to the central locking.

 
Hi All,

Sorry, I've been a while getting back to report on the central locking problems.

I had to admit defeat in the end and take the vehicle to my local friendly auto-electrician.

He diagnosed a faulty module on an after-market (not fitted by me) alarm system. After disconnecting it the car now locks and unlocks perfectly.

Many thanks for all the responses with advice from various members, especially Indischrot. I am most grateful.

Regards Gez

 
You must log in or register to reply here.

Posts made and opinions expressed are those of the individual forum members

Use of the Forum is subject to the Terms and Conditions

Disclaimer

The opinions expressed on this site are not necessarily those of the Club, who shall have no liability in respect of them or the accuracy of the content. The Club assumes no responsibility for any effects arising from errors or omissions.

Porsche Club Great Britain gives no warranties, guarantees or assurances and makes no representations or recommendations regarding any goods or services advertised on this site. It is the responsibility of visitors to satisfy themselves that goods and/or services supplied by any advertiser are bona fide and in no instance can the Porsche Club Great Britain be held responsible.

When responding to advertisements please ensure that you satisfy yourself of any applicable call charges on numbers not prefixed by usual "landline" STD Codes. Information can be obtained from the operator or the white pages. Before giving out ANY information regarding cars, or any other items for sale, please satisfy yourself that any potential purchaser is bona fide.

Directors of the Board of Porsche Club GB, Club Office Staff, Register Secretaries and Regional Organisers are often requested by Club members to provide information on matters connected with their cars and other matters referred to in the Club Rules. Such information, advice and assistance provided by such persons is given in good faith and is based on the personal experience and knowledge of the individual concerned.

Neither Porsche Club GB, nor any of the aforementioned, shall be under any liability in respect of any such information, advice or assistance given to members. Members are advised to consult qualified specialists for information, advice and assistance on matters connected with their cars at all times.

Porsche
Lockton
Pirelli
Officially approved
Oracle Finance
WEX Esso
Collecting Cars
Archant Dialogue
Back
Top