Okay, can you lock/unlock with the fobs? Doing that suggests that the fobs are functioning ok.I'm sure u know that if functioning correctly as soon as u unlock the engine is remobilised, if you happen to delay starting the immobilised symbol illuminates on the dash indicating the engine is again immobilised, placing the fob near the ignition switch or pressing the unlock button will extinguish the symbol and again remobilised your engine.
When a UK spec disco left the factory the key number was supplied on a metal tag attached to the key, with the security card giving the EKA code plus wheel lock and radio code.
If u unfortunately find the 'spider' is faulty it can be simply bypassed with a switched 12v directly to the two areas that are immobilise,info on that is already on the www. so no need to pull the dash apart if you don't want to.