Re:ALARM GOING OFF AGAIN

I thought I had the work on the car finished with it running great .I isolated the battery a couple of days ago as I always do when finished messing with it ,Ive just been into the garage and when I tried to start it no joy and the alarm is going off ,not the horns The battery is fine showing 12.85 volts and its new The key fob isnt working either .Any ideas Its a shame a beautiful little car in excellent condition but Ive just about reached the end of my patience with it Len

You have Lucas alarm system. That means whenever you disconnect battery either in the car or in the fob itself you need to re-sync all fobs you have with the alarm system in the car.
To do that you need to press unlock button 4 to 5 times within the car to be sure you are close enough to alarm box in the car. Then your fob should be re-synced and you can use the fob, disarm the immobiliser and start the car.

So, do not forget that whenever you disconnect car battery you will need to re-sync all your fobs with the car.

Thanks ,but the key fob has stopped working it was fine a few days ago . I put the key into the door and made sure it was open the pressed the button 10 times and it worked now ,nothing when the key is pressed

Ive held it as close as possible to the alarm box

It is completely fine that fob worked 10 days ago. Then you disconnected car battery and fob stoped working and it will not start working until you connect car battery and made re-sync proces. This is the way how it works. Car is not designed in a way that car battery is disconnected.
So if you disconnects car battery, you need to follow the rules above described.

I imagine that you unlocked the car but car battery was still disconnect and fob is not working because car battery is disconnected. The receiver in the car is not working becuase car battery is disconnected.

Over the years I’ve never know an alarm system that is worth the trouble, the sooner we can figure out how to disable the damned things the better.
And it comes as no surprise that an alarm like anything else made by Lucas is going to be a pain in the arse.
I haven’t had any alarm going off problems but the bastard of a thing has flattened and thereby wrecked a few batteries.
Sooner the prick of a thing is disabled the better………. and to hell with insurance companies… my car is insured by Smith & Wesson!

And if disabling the alarm also disables the remote locking in the process, I couldn’t care less, it no trouble or great hardship to use a key! I managed to get by for many years without remote locking, in fact I’ve managed to disable it on my Ford Ute, and couldn’t be happier with the result, doing so banished many silly niggiling problems with Ford’s Smartlock system (should be Ford’s Dumb-as-dog-shit-lock system)

No I connected the battery as soon as I went into the garage So the battery fully charged,has been on every time ive tried to start it

Why are you disconnecting the battery? It would be more understandable if you were working with a car with leakage current around an amp, but to all intents & purposes you have a modern car which has volatile electronics; disconnect & stored information is lost. If you're concerned about the battery going flat buy yourself an intelligent charger which can be left on permanently. My old Land Rover hasn't moved for quite a while & I can start it at will as I built a cheap charger into it.. My wife & I have had Rover cars from the seventies onwards, the latter ones had the Lucas alarm system & we haven't had any problems, there must be millions out there all over the world, yet I see more alarm grumbles on the t-bar than I've seen elsewhere. You've sorted your car once don't break it before the fun begins.

digcot65 wrote:

No I connected the battery as soon as I went into the garage So the battery fully charged,has been on every time ive tried to start it

Because you disconnected your car battery you will not be able to start your car until you make re-sync proces of your fob/s with your car.

Morning I had a fairly new battery on the MG but it kept losing power,so I thought I had a drain on the car.That was why I disconnected the battery every time .I sent it back to the suppliers and they found it to be faulty They supplied a new battery,to replace it so I realise now I should have left the new one connected. I cant get the key fob to work,even with a new battery in it .So I have booked a diagnostic test for next week,to get it sorted once and for all . I am also going to ask,for the alarm to be disabled as they are a dam nuisance, how many cars do you hear,where the alarm is going off and no one takes a blind bit of notice The day is quite nice for a change,so Im off to the Pride of Austin show at Cofton Park today.Its only a mile from where I live ,also I worked there for 12 years Len

Have a go at cleaning up the contacts on the bonnet open switch. They can corrode and cause iffy connections. It can set the alarm off.

Sundance

Do to problems with the alarm,I`m having a diagnostic check on the car next week I asked the engineer,if it would be possible to disable the alarm as its not worth the trouble to keep it .He did say that if that is done, I need a 12 v supply from the ignition to feed the ECU .I thought I would be able to do this ,from the distributor as in older carS,I cant see a 12v supply going to it .Where is the best point to pick a supply up from.
The Austin show at Cofton Park yesterday wa excellent and surprising,how many MG F/TFs there were great show friendly people a great day out .Len