immobiliser

Hi all, new to this forum & semi new to landrovers, had a series 2a about 15 years ago. Anyway i've just bought a 1996 discovery van 2.5tdi from the company i work for 140,000 miles £1800. Its been well maintained & has a new gearbox but is filthy inside. However it has an intermittent immobiliser problem, sometimes it starts & others it wont switch off so i'm unable to start the thing. Is this likely to be an expensive problem to fix or quite straight forward, i think i've read on here about a bypass lead being available ? Any ideas would be appreciated. Thanks John

Hi John
The part you have trouble with is called a spider, the problem with them is when you get dry joints on the pcb,which need resoldering. i did mine last night and it took about 1.5 hrs start to finish. the spider is buried behind the center console, you need to remove the radio ashtray clock etc. have a look on the difflock forum and search for spider, someone on there has posted very detailed instructions on how to take the dash apart. original spiders are no longer available, you can get an overide plug that replaces the spider but then you have no imobiliser. the other option is a third party replacement, there is a company that do there own version for about £80, do a search on google and you should find the company. i would try and repair it first, its not that difficult once you get to it.
good luck
Paul