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MG MGF Technical - Odd alarm behaviour

For the last few weeks I've had quite a few occasions where the remote lock & unlock functions go on strike. Often, when I try to lock the car with the key, the knob pops down to the locked position, then the lock motors whirr a bit, and unlock again. This is sometimes followed by the alarm sounding (usually only when it's very late at night!). Most of the time I can silence the alarm with repeated presses of the unlock button, but not always..! I've noticed that when this has happened, the immobiliser does not automatically set, which means leaving the car not only unlocked but un-immobilised. The problem seems to correct itself in its own time - disconnecting the battery overnight, re-synching the remote, tried all these but no improvement.

I don't want to book the car for a TestBook diagnostic if it's likely to be something simple. I had suspected it was a faulty remote, which could explain the random occasions where communication fails and I resort to the key override code, however this latest behaviour suggests there's a problem with the onboard system. Has anyone had this? Any clues where to start investigations would be much appreciated!
J Fox

hi mate i have that problem at the moment. with the superlock it chatters like hell help needed also anyone
Darren Jeffery

A good start maybe a new battery for the remote? Older cars are known to have trouble with micro switches in the door lock causing chatter and alarm problems. If that's the cause, change micro switches, cheap fix but a pain or fit new lock expensive. Low 12 volt battery also can cause unexpected happenings.

Ken Waring

thanks ken where do you get the micro switchs then ??for the door who stock them?? its a weird on it working fine now then it goes awol again

darren
Darren Jeffery

Switches are original *Cherry*
http://www.mgfcar.de/door_lock/index.htm
Any other from that standard may do it also.
Dieter

Either Maplin or RS. The switches(not expensive) are Cherry DB series but there are a few variations. I think I've still got a couple left. I'll have a look in the morning and post the part number. Be aware there's some fiddly work to do. The switches are a press fit into the circuit which IIRC is stamped out of brass sheet. The new switches have to be soldered in to ensure good contact,not that easy. A long plunger/actuator has to be made(bodged) from one of the existing switches. My motivation was to save my daughter £67. If you need to save the money go ahead, if not buy a new lock. I've got some photos somewhere I'll see if I can find them.
Ken Waring

No need. Dieter to the rescue.
Ken Waring

Thanks Dieter, very useful. Although it seems my car has very early door locks fitted, with a different wiring configuration, which I can't find a diagram for on the RAVE disc.

Does the door closure circuit use the door latch for its input? I'm not sure what the alarm is supposed to do if it is sensing a door open, does it just ignore the keyfob 'lock' instruction?

Fuse for the interior lights/clock/immobiliser LED keeps blowing too, and not it seems due to chafing behind the radio. Can boot wiring faults cause problems on this circuit, or the alarm/immobiliser circuit?
J Fox

Yes the boot is also on the alarm circuit so a fault there could have an effect on the whole alarm circuit.
Ted Newman

This thread was discussed between 18/05/2007 and 21/05/2007

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