lilium.don

Hi Everyone and thanks in advance for any input. The car is 1991 964 with the central locking unit/alarm located underneath the passenger seat.

At the moment I am unable to lock the driverside from the outside and I am getting no response from the central locking/alarm computer, no flashing LEDs, no actuator movement, no response from the door handle micro switches, and no response from the center console button. It is a Targa, and corrosion was present on the connectors, I have cleaned all oxidation, replaced the 15amp spade fuse on the control unit, and confirmed that I have 12V on the black connector at terminals 1 ,14, 15. I have also confirmed that the microswitch on the drivers door is functional.

Should the 15amp spade fuse on the back of the unit have power at all times?

Without the factory tool, does anyone have some troubleshooting procedures for the unit?

Deserion

The Durametric also can diagnose the fault codes in the alarm.

When you mean you can't lock the driver's side from the outside, is that can't physically lock or can't engage the alarm? And the 15a fuse was in the main fuse panel or on the alarm module itself? Apologies, it's been a while since I've looked at the module on mine.

I'm trying to go through the wiring diagram for this.

lilium.don

Thank you for the reply. I was unaware that the Durametric was able to diagnose the alarm system. I can't physically lock the car from the outside, I can unlock it though. Which looks like how the mechanism is designed, to unlock mechanically, but use the lock actuator powered by the central locking computer to lock it. The 15ampfuse I am referring to is on the back of the central locking unit.

Thanks!

bw-porsche

Is your battery up to scratch? I hadn’t been able to lock my 1990 C4 coupe with the remote or anything else, for a long time and kept it on a CTEK battery conditioner. I very recently had to renew the battery and as soon as connected up I heard the central locking operate. So I unlocked and locked a few times just to confirm it worked properly. Also if the battery is not in great condition and you lock it up, it will unlock itself! Must be a fail safe so that you don’t get locked out. This definitely happened to me. So check on your battery before doing anything else as it is key to the car working!

lilium.don

Battery is brand new. Thanks!

Mr.Alex

Check the fuse in the frunk/trunk, it will be listed under "Central Locking"

bw-porsche

There is another check you can make and that is the central locking control module, part number 911.618.113.00 or 01 maybe. This is situated on the passenger side in the footwell, just under the dash. I have attached a photo of the box itself, about the size of a pack of 20 cigarettes. You will need to be a bit of a contortionist to see it, but it’s there. Detach it and then pull out the wiring plug in and it will be loose. Then you need to carefully extract the printed circuit board by slightly levering out each side and then it will slide out. I have attached a couple of photos showing the PCB and on the far right there is a shiny looking little strip of metal which should be soldered to a resistor (not too sure if a resistor or capacitor). Look carefully to see if the solder is alright and making contact with the resistor/ capacitor if there is a gap, then this needs soldering up! If it is ok then try and get an electronics engineer to check the complete PCB out for faults or maybe just get another module from EBay etc. Good luck.

bw-porsche

Any update on your problem yet Lilium.don?