Can not start TD5 engine

Hi all,
I am a newbie to LZ and Landy's in general and need help.
I can not start my 2001 defender TD5 engine - the immobiliser light (cobra) does not come on at all and the temperature gauge rockets to hot when key turned despite the engine not turning over. Was working perfectly until Monday.
From reading a little around this I am putting money on the ECU or earth to ECU but would value others thoughts - there snow is coming and I could do with this getting off the drive in the morning!
Have been into the area under the seat and it is damp, but earth point looks intact - what is the next step?
Battery is fully charged.
Any help gratefully received.

MarcoG

Earths, lives and check the inertia switch wiring

Will do - thank you

i'm still confused, is it cranking or not?... if it's not cranking forget the ECU and inertia switch check starter motor connections/relay feed

Run a earth from battery to the black wire on the earth pole . make sure its deffinately got a good earth . strip some insulation off the wire to be sure . temp gauge stupidity while cranking is nearly always a sign of lost earth to ECU . it won't cost anything to try

Classic ECU earth fault. Temporary earth cable from battery to ECU earth point will confirm. Take off and clean then retighten all earths with some petroleum jelly. Dont use copper grease as it eats the aluminium when an electric current is passed.

hi i had same problem when i first got my Td5 turned out to be faulty wiring from accelerator pedal which then spiked the ECU and buggered it,so the landy garage said new acc pedal and wiring second hand ecu and all fixed lol