This failed to start after being switched off. It will not crank but starts on a bump.

When I saw it first it was in economy mode. battery voltage was at 11.98v. Bumped it, ran it, charging ok and battery volts came up to 12.4 at rest. After switching it off and trying to crank again it went into economy mode again.

Looking at actual values in BSI the T50 start position is not recognised. There is a T50 output from the switch.

My understanding of the circuit is (someone please correct me if I am wrong) T50 from the switch is a voltage signal to the BSI, the start signal from the BSI is CAN to the under bonnet fuse box, the fuse box triggers the starter relay which outputs voltage to the motor.
This being right then my problem seems to lie with the BSI.

I don't know the economy mode very well but I would think the BSI would control it. If the BSI is seeing low system voltage then I could have a wiring/supply fault to the BSI.

Anyone any thoughts on this?

cheers