went into the garage tonight to start stripping the donor but wanted to check everything was ok so i tried to start it up. i new the battery was flat as its been stood a while and was only putting out 1.02 volts. i connected the jump leads to it and the hazzard warning flashers were flashing and would not turn off.then alarm started beeping for about 20 seconds, then the alarm would sound until i removed the jump leads? when i put key in to ignition and turned it. dash display lit up perfectly but start button would not fire! and as the alarm was so loud i had to remove jump leads asap. any thoughts?

Had this on my car with an old (10+yrs) alarm - i just needed to reset the alarm after the flat battery activated it.

Sounds like you have answered it. It has an alarm and immob. The alarm sounds becasue the bat is so flat.

Things to try:
Before you connect the battery stuff an old towel right down the siren. Dont cut it off! This is quite it down lots.

If you have got the key fob for the alarm put the jump leads on, wait for the noise to start then press the button untill in disarms. The car SHOULD then start.

Look at the siren. If it is big with more than two wires it will probably be a CAT 1 alarm. That means two seperate immobaliser cuts and a well fitted alarm. If it is only two wires and a small siren it is probably not cat 1.

Use the siren wires to find the alarm brain and then start chasing wires to understand where the cuts are.

HTH

i have the key fob and pushed both buttons but nothing happened. battery was ok in th fob 9.6v

I had a clifford alarm imobaliser die in this way, aparently they dont like being left to go flat unless they are placed in valet mode and it is hit and miss wether reconnecting them will kill them.

Is it a proper factory fit alarm/immobilizer? If so fit a known good charged battery with proper leads, not jump leads. Some leads from an old car bolted to the original battery terminals & taped up to insulate & the other end on the battery with good clamps will be far better than jump leads.
With the correct key/fob & good stable voltage I think it'll sort itself out.

I'd not have the original battery from the car connected at all, it's probably faulty from having stood & may be abosrbing much of the charge instead of it going to work the electrics on your car.

[Edited on 23/2/10 by hillbillyracer]

What alarm is it?

Try locking and unlocking with the fob, remember you may have a bonnet switch you will need to push in to make it think its all locked up