I've had an issue previously after some welding work was done (this is actually on a Disco 2 but its the same part used on the p38) where the inertia switch was tripped, this gave a few symptoms as follows
Failure to start (Cranks but not firing)
Hazard lights flashing when trying to start
Diagnostics fail to connect
Above was obviously sorted by resetting the swtich. However that was several months ago, Today I've driven the car around 35 miles and around a mile from the end of the journey pulled up at traffic lights. On pulling away car suddenly isn't running right (its been fine prior to that) Limped it the last mile or so and left it for a bit at that point.
Tried to start it a couple of hours later - LPG system is in protest mode (beeping) and engine clearly isn't running right. So out comes the Nano - which will not connect to the engine ecu no matter what I try (its been fine previously). So fire up the diagnostics for the LPG and find thats its complaining of several errors, some of which are probabbly from the original inertia switch incident, but 4 current ones are "petrol injector no signal on channels 2/4/5/6" which would explain the symptoms. live readings also show 0 for those 4 channels (2 and 4 would be the drivers side bank, 5/6 the front two on the passenger side bank)
My first thought was damaged wiring, but I think this unlikely as theres no obvious evidence of any damage, and for all 4 to fail like that seems unlikely. It also wouldn't explain the lack of diagnostic connection though the Nano either. I don't have anything unusual happening with the hazard lights on this occasion either.
I've checked Rave, but it has very little to say about the switch or how to test it. There seems to be 3 wires to it, does anyone know how the connections should be if checked on a multimeter or how it actually works? Or is it possible to bridge out connections to remove it as a possibility? If it was 2 or even 4 connections it would make more sense to me, but 3 doesn't give me much of a clue what it should be doing without another to compare it to?
Or does anyone have an idea of something common to both systems that could be causing the problem? Its a 2000 Thor 4.0 if it makes any difference. Obviously a lot of the bits differ between the p38 and the D2 but I'd imagine the basic engine electrics are fairly similar?