Bit of an update, firstly I failed to start the TD6.
Allcomms would connect ok to some systems but not engine, comms error which makes me think it isn’t powered.
No immobiliser faults showing.
Tried cranking and got nothing but would crank yesterday before battery removed to charge.
Tried clearing some faults and checking wiring and would then crank but only an interrupted half crank as if it would crank half a turn and stop and then half a turn then stop.
Then noticed no dash lights and then no crank at all again again.
Checked all fuses in glove box and engine ECU box and all ok.
Tried jumping but made no difference , battery seems good at 13.5 volts plus but tried other battery to rule that out.
The temp gauge is now normal having been replaced, inlet manifold removed to achieve this.
I didn’t try adding a jump lead from the negative battery terminal to the engine to make sure Earth was ok.
My other thought is ignition barrel contacts
Need to confirm power going to fuses
Any other ideas please ?