ZippyEFC

My central locking stopped working via the alarm but is fine via the key. I removed the door card and checked the universal actuator they fit with these alarms(its a cobra) with a multimeter. The problem is both wires get a signal when you activate the alarm and neither get a signal when you deactivate it. When you conect the wires to a battery it works fine. Any ideas anyone? I was hoping it was the actuator they're only £8 from Maplins

R*** ANT

Had the same prob with mine just replaced the actuator for the alarm and hey presto all working again.

ZippyEFC

What both wires were getting a signal at the same time or it just stopped working and you changed it? I've tried a new actuator and no joy

ZippyEFC

Where will the relays for the alarm be?

R*** ANT

mine just packed up so took off actuator and put new one on to be honest never tested it, or the wires, as I had a spare actuator in the garage. Sorry not much use.

ZippyEFC

No worries m8 at least you've replied, i dont think many people look in here lol

Sigma Sam

Based on the fact you have this system fitted, as opossed to the standard UK Sigma system, I am presuming the car is an import or a pre-99MY?
If this is the case then the solenoid in the driver's door will be an aftermarket item of unknown origin.
The solenoids in the driver's door on the Sigma equiped UK models 99-00 have been known to fail, so most posts you will get back will advise you to change this, however, from your description of the fault it doesn't sound like the solenoid is the cause - although it could now be damaged depending on the nature of the fault.

When you say "a signal" do you mean "+12v" ?
Normal operation of the solenoid requires a constant earth on one of the wires with a brief +12v pulse on the other before returning to earth. The +12v pulse will alternate from one wire to the other when locking and unlocking.
Ensure that you test this on the wires with the solenoid disconnected. If, you are not getting this pulse it would suggest that Cobra unit, the OE CDL Relay or wiring is at fault.

Pre 01MY vehicles had OE central locking, but only when operated from the key in the driver's door. OE solenoids were fitted in all but the drivers door and these were energised from an OE CDL Relay, controlled by a switch on the rear of the drivers lock barrel. The relay was switched by "single wire" control (when the wire went open circuit, as a result of the key being turned in the drivers door, the other doors would also unlock).
The operation of your system will depend on the Cobra system's installation method, but generally I would imagine that the alarm unit is simlpy operating the locking by making/breaking this control wire to the OE CDL relay and an aftermarket solenoid will have been fitted to the drivers door, connected directly to the solenoid output wires to the passenger door.

Hope this gives you something to go at.
SS

ZippyEFC

Cheers for the reply m8. I've sorted it, it was a connector at the base of the A pillar by the drivers feet