original alarm

[bjdp]

help pls..... i have a 1988 e30 convertible and it has the original door alarm (the one with the big hole in the drivers door where you insert a round looking key) my one dont work so im taking it out of the car the only problem is that the main module if i disconnect the small plug it disables the engine(it turns but doesnt fire up)the other bigger plug is ok to disconnect to remove
does anyone got any ideas about removing this module fully(my module is green in colour if that helps)
thankyou