Immobiliser / Central Locking problem.

[Ian21401]

Help needed please?
1992 940 estate. Fitted with a Gemini 402 RED immobiliser/alarm system. It was in the car when I acquired it in 2005 so I don’ t know whether it was a factory fit or dealer fit or a retro fit. The control unit is fitted on the left side behind the glove box with a siren/horn fitted to the bulkhead in the engine compartment. The horn has a key operated off/on switch which I have the key for. The key fob has no identification on it. The fob only has two buttons, one red and one black. The red activates the alarm. The black one activates the on/off.
The above system is connected to the central locking. When working correctly the central locking locks or unlocks as the alarm system switches on or off.
Recently, when using the lock/unlock button on the fob the alarm system switches on or off as required BUT, the central locking attempts to activate to lock or unlock but does not do so. The buttons on the doors try to move but do not move fully. If unlocking, I then have to use the key to unlock the driver’s door. This activates the entire central locking system correctly.
If locking the car the same applies, the central locking attempts to move but does not move fully. I then have to use the key to lock the driver’s door which activates the central locking system correctly.
If I try to lock the car with the key in the driver’s door lock without first setting the alarm via the key fob the key will not turn so locking is not possible.
If the car has been locked and I unlock the front passenger door using the key it does not activate the central locking system, only unlocking that door, but that has always been the case.
It appears to me that there must be some device within the driver’s door which activates the remaining locks in the car and this seems to work when the key is used but there must also be a device linked to the alarm/immobiliser system which activates that device and for some reason it is having difficulty in doing so. I suspect that it could be failing or just that some strategic lubrication is required. I don’t know whether this is relevant but this problem has only occurred following the onset of the colder weather.
As I know nothing about any of the components of these systems the Forum’s comments and guidance will be appreciated.

[Laird Scooby]

You'll need to remove the drivers door card to be certain Ian but i'm fairly sure you'll find something like this in there :

https://www.ebay.co.uk/itm/CENTRAL-L...Y/230782233283

Chances are, it's worn out and the original locking mechanism won't work anymore because the solenoid has gone stiff. For the cost, you might just as well try a new one but also lube the latch on the door as well.

Once you've found the aftermarket actuator/solenoid (the drivers door never had an OE one on early 940s, only later models, likewise the passenger door didn't have the switch for the locking/unlocking), if you remove the two self tappers so the whole assembly is free to move up and down, you should be able to lock and unlock the drivers door with the key and also by pressing the lock button down and pulling the door release internal handle to unlock.

The Gemini alarm/immobiliser was an (Thatcham Approved Cat1 if memory serves) aftermarket system, usually fitted by autoelectricians and/or car security specialists. Was a good system at the time, not cheap either!

Had a similar problem with my 760 recently, a bit more serious for me as the previous owner lost the original key so the aftermarket solution was fitted with a secondhand ignition barrel, leaving all other locks inoperative with the key!

[Ian21401]

Thanks Dave, I suspected that you would know something about this. Thanks for the info. re the Gemini system. As I had never heard of it I did not know whether it was quality or cheapy, although it does appear to have been installed well. The red led on the steering column shroud still flashes when the system is armed and the alarm still activates if it monitors a change in current drain.
So, as I understand this in non technical terms, there is an actuator installed in the driver’s door which is activated by the Gemini system. This somehow operates the door lock, which includes a switch which in turn activates the central locking.
As you state, either the actuator is failing or the door lock is too stiff for the actuator to move it and needs lubrication or a combination of both. I’ll get to it as soon as time, weather and other commitments permit.

[Laird Scooby]

Originally Posted by Ian21401

Thanks Dave, I suspected that you would know something about this. Thanks for the info. re the Gemini system. As I had never heard of it I did not know whether it was quality or cheapy, although it does appear to have been installed well. The red led on the steering column shroud still flashes when the system is armed and the alarm still activates if it monitors a change in current drain.
So, as I understand this in non technical terms, there is an actuator installed in the driver’s door which is activated by the Gemini system. This somehow operates the door lock, which includes a switch which in turn activates the central locking.
As you state, either the actuator is failing or the door lock is too stiff for the actuator to move it and needs lubrication or a combination of both. I’ll get to it as soon as time, weather and other commitments permit.

You've got it in a nutshell Ian - i have a spare switch now as when i had to replace the latch on mine because it failed (which caused the failure of the aftermarket solenoid) the one i bought had a solenoid and switch built in. As in a Volvo OE solenoid - the switch was a straight swap (same plug) and i had to make new connections to connect the Volvo solenoid in place of the aftermarket one but it all works well now.
An option for you might be to get in touch with Mark (Griston64) and buy the latch/solenoid assembly from his 1998 breaker. That all depends what you find when you pop the door card off though.

[Ian21401]

Thanks Dave. It sounds as if the actuator is trying to move the lock but for some reason cannot do so. As the central locking works fine when I use the key in the lock it would appear that the switch is ok.