Door locking

I have looked through everthing concerning lockihg systems and cant find the problem i have!

When i lock the disco using the key fob or the key the horn sounds once even though all doors are shut! Problem i have is, i have a leaking rear air bag, so the compressor won,t cut in cause it thinks theres a door open!

What can i check to see what doors casuing the problem?

Its a disco td 5 2004

Any help much appriciated

If the courtesy lights come on and go out as they should then I would say that the BCU is seing all the doors as closed.

There is another swtch which can cause the alarm to beep once when locking and that's the bonnet switch. I don't know whether it would cause the SLABS ECU to register a door open, but it's worth a look.

I had a similiar problem ,turned out to be the bonnet switch rubber had split,that was causing the horn to sound when locking.

Hi,
Thanks for the replies, its all back to normal, without me touching anything, have no idea what was wrong but will keep an eye out for the bonnet switch, in case it happens again.
Thanks again
bawbag

I have the same problem occasionally, it's the bonnet switch that's the cause, if the rubber cover is not on correctly, (usually if I have been under the bonnet for maintenance and touched the switch and not noticed) repositioning the cover to it's correct location cures the problem.