immobiliser problem
 

Hi everybody, let me start by saying this looks to be a very handy website. I have a 2003 Voyager 2.5 crd that's been messing me around, when I start it the engine runs for about 3 seconds then cuts out, it may do this 3 or 4 times and then run fine or the immobiliser cuts in and it won't turn over or anything. All the dash lights work fine and I'm getting a skim code p1685 for key not recognised, I've been looking on the forum and pin 21 behind the heater panel has been mentioned regulary, so I took out the heater panel, but I have 2 electrical connectors, neither have 21 pins and are numbered up to 13. I'm wondering if the transponders suffer from bad connections. Any help will be gratefully received, thanks.

What is the immobiliser? Is it one of those things that you get after a DUI?