Land Rover Repair: 1995 Discovery 1 V8i no start

Question
It cranks fine but very intermittent or no spark.  Just the following please:  
1.  Two experts advised adamantly that I must bridge the "spider" behind the radio fascia.  Another expert advised adamantly that my vehicle does not have a spider.  I opened all that and my 1995 Discovery 1 V8i does NOT have the "spider".  My question 1: How can I isolate the immobiliser as I firmly believe after many replacements of components that this is my problem.

2.  One expert adamantly advises that I replace the throttle position sensor (TPS) because in his case that had solved his no start problem.  Here is my question 2: What does the TPS do and how does this affect starting?  (It is an ignition problem I have and already have replaced the ignition amplifier module twice as well as the ignition coil).

Answer
The 1995 Discovery has 14CUX fuel injection and a distributor.  The spider is found on newer vehicles with distributor less GEMS engine management.  In your truck, the spark is all determined by under hood components.  You have power coming into the top of the coil, and from the bottom of the coil you go into the ignition amp and from there to ground.  The ignition amp is in turn connected to the pickup in the distributor.

Depending on what updates your truck has the amp and distributor may be together as one piece, or separate.  If you have power coming in to the coil the spark loss is one of the components above, or the coil, cap, or rotor has failed.  You can buy a reproduction distributor from the mail order suppliers as the factory parts are long discontinued.

If you have power to the coil and power to the fuel pump when cranking the vehicle is not immobilized.  Immobilizer trouble is very rare on 14CUX systems.  It's the newer cars where you see that