My first Post! I have owned a '96 defender for 4yrs, the immobiliser part of the alarm system had been bypassed before I bought it, other bits OK. In October both horn and alarm siren ceased working, checked and both dead and replaced. Worked OK until 3 weeks ago except that key fobs would not always deactivate system, using the other fob (both with new batteries) would do the trick. Days later the reverse would happen and I would change fobs again.
3 weeks ago the horn sounded of its own accord when car had been stationary for some 4 hours, horn was intermittant but had the be disconnected to stop it. Alarm still set OK, lights( indicators) flashed etc. Car was unlocked and alarm not set
Yesterday the alarm siren also sounded intermittantly and would not stop ( at 6am) and I disconnected that. No lights flashed, alarm could still be set and unset according to flashers.
My guess is I need a new control unit. If so, would I need new fobs?