Alarm going off during the night

Hogweed wrote:
Ummm… that little connector… so can I just disconnect the microwave sensor with that?

Yes, you can. Disconnect the plug and sensor will be inoperable. Then you could lock the car wirh fob and sensor will still be inoperable.

Sorry I am a bit late to the party but...….

Not all cars have the microwave sensor.

When my boot loom failed it was just where the wires come out of the main loom, a real pain to get to when soldering or crimping, I ended up stripping the boot wiring out of the main loom all the way back in to the rear shelf and re-routed it.
I have also been working on a curly sprung patch repair, if it works I will be offering them for sale.

The wiring of the boot lock switch is opposite in function to the rest of the alarm system. There is a feed to the switch and a return back to the alarm, when this circuit is completed by the boot being unlocked and thus the alarm knows not to trigger when the boot is opened. Strangely one of the wires in this circuit is the same colour as for one of the rear lights so caused me great confusion when I was altering and re-routing my rear lights.

talkingcars wrote: Not all cars have the microwave sensor.

GAAAHHHH!!!! Looks awkward to get to too, but I’ll have to if I want to find out, I guess…

talkingcars wrote: When my boot loom failed it was just where the wires come out of the main loom

Do you mind my asking how you knew there was actually something wrong with that part of the loom in the first place?

talkingcars wrote: The wiring of the boot lock switch is opposite in function to the rest of the alarm system. There is a feed to the switch and a return back to the alarm, when this circuit is completed by the boot being unlocked and thus the alarm knows not to trigger when the boot is opened. Strangely one of the wires in this circuit is the same colour as for one of the rear lights so caused me great confusion when I was altering and re-routing my rear lights.

Hhmmm. If I understand you correctly… doesn't seem to be a return to the alarm on mine? Just a single wire/connector to the boot switch…

Yeah my car doesn't have a microwave sensor, which is odd as Oz spec cars came fully loaded with all the bells & whistles.

It is true that not all cars have microwave sensor. However it is easy to check if you have it or not. Leave door window in down position, close the car with fob and let few moments to pas. After that wave by your hand several times. If alarm goes off, then you have sensor, if not, then most probably you do not have it.

There are two boot switches. The one on which you made correction of the spring (let us call it boot lamp switch) and boot lock switch.
On both switches you have two (2) wires. Boot lamp switch have two single wire connectors going onto it. Boot lock switch have two wire connector. Take a look at picture I provided earlier on this thread.
Feed mentioned above is nothing else then earth wire from same position in the car as for door switch. This feed does not come from alarm, but from earth connection. Return wire is the one that goes to alarm. Black wire is earth feed and return wire is couloured one.

In case of mk1 MG F cars earth feed for boot lamp switch comes from another earth point then door and boot lock switch.
In case of mk2 MG F and MG TF cars earth feed for boot lamp switch and boot lock switch comes from same earth point connection.

Roverlike wrote: It is true that not all cars have microwave sensor. However it is easy to check if you have it or not. Leave door window in down position, close the car with fob and let few moments to pas. After that wave by your hand several times. If alarm goes off, then you have sensor, if not, then most probably you do not have it.

Makes sense, thanks - I'll try that later.

I've been locking the car with the key since I fiddled with the boot switch. Now, I don't want to tempt fate by pronouncing the fatal words "It's been OK so far..."

But...

talkingcars wrote: Sorry I am a bit late to the party but...….

Not all cars have the microwave sensor.

When my boot loom failed it was just where the wires come out of the main loom, a real pain to get to when soldering or crimping, I ended up stripping the boot wiring out of the main loom all the way back in to the rear shelf and re-routed it.
I have also been working on a curly sprung patch repair, if it works I will be offering them for sale.

The wiring of the boot lock switch is opposite in function to the rest of the alarm system. There is a feed to the switch and a return back to the alarm, when this circuit is completed by the boot being unlocked and thus the alarm knows not to trigger when the boot is opened. Strangely one of the wires in this circuit is the same colour as for one of the rear lights so caused me great confusion when I was altering and re-routing my rear lights.

Am going to have to break into my rear loom in the bend from the boot lid - my reversing lights and upper break light are no longer working :rant:

Roverlike wrote: It is true that not all cars have microwave sensor. However it is easy to check if you have it or not. Leave door window in down position, close the car with fob and let few moments to pas. After that wave by your hand several times. If alarm goes off, then you have sensor, if not, then most probably you do not have it.

Hhmmm. Well, I tried this just now - both windows fully down, locked with fob, went in and unloaded my shopping etc, came back out a couple of minutes later and stuck my head through the window, and waving a shopping bag around... nothing.

So it looks like maybe I haven't got a microwave sensor.

The only other thing I've noticed is that the false alarms may possibly only have happened on frosty nights - haven't had one of them since I fiddled with the boot switch... has anybody else found this problem to be temperature-related?

Well, if you do not have that sensor I even more cannot see how your problem could be temperature connected.

Only in case we will make hypotesis that spring in your boot switch was in such state that it could or could not make connection and because of temperature changes, metal was contracting and expanding. Since spring is bare metal, in such case, hypoteticaly, it could make contact when it was not expected.

In above caee, when you corrected the spring in switch you solved the problem.

However, I cannot remember if you had one time more after you corrected spring, when alarm went off during a day? In that case above is questionable.

Roverlike wrote: However, I cannot remember if you had one time more after you corrected spring, when alarm went off during a day? In that case above is questionable.

No - I can't remember either - d'ohhh!

We'll just have to see, won't we. However long it takes, I'll be sure to report back here if it goes off again. I know one thing - I don't trust that damn Pektron thing. It's known to have all sorts of issues (eg relays failing - but mine have already been replaced; and another fault which means the key fob has to be very close to the car to lock or unlock it - I've had that fixed too).

Thanks everybody for your help with this :clap:

Come on Hogweed, have faith in what you have done . As you have admitted to not being mechanically minded , I think you've done really well so far . As for Pektron, you've probably sorted that area unless you get damp or water leaks getting into the car that will affect it .
John

sworkscooper wrote: Come on Hogweed, have faith in what you have done . As you have admitted to not being mechanically minded , I think you've done really well so far . As for Pektron, you've probably sorted that area unless you get damp or water leaks getting into the car that will affect it .
John

Thanks John, you're very kind. Did I say that? Actually I am quite mechanically minded, just don't know how modern cars are put together so can't make sense of things (carburettors, grinding valves etc no problem ) Also the fingers shake a bit now, eyes need glasses, and suffer badly from stress, so end up breaking things :rant:

The good news is that the wee car has given me a new source of entertainment in my old age - love driving it