This is a very ugly defect cos it's completely out of any path, it can be a misscommunication between the IDM(interior fusebox) and BCU even though then it should be immobilised which is not, if it was a XYZ fault it should have triggered the flashing M+S warnings as well, it's certain that the BCU is missing something but i can't imagine, what, i suspect the P/N input which should be earth to BCU C0663-11, so chek if there is earth there when P is selected cos if it's not that's the problem, then it can be a wiring issue between the XYZ switch and BCU or within the switch if there isnt earth with P selected at C0675-5, it's a BG wire all the way but it goes through a connector under the console and a header so might be that path
the gist is in this part of the BCU's operation i suspectbthat autostart inhibit cos all the others would trigger an immobilised status:
Starter relay
The BCU checks the status of the following inputs and internal BCU conditions to determine whether or not to provide
an output to enable the starter relay:
l Autostart inhibit (vehicles with automatic gearbox only).
l Security start inhibit (immobilisation check).
l Engine running (link to instrument pack).
l EEPROM locked (internal check).
l IDM and BCU matched.
When the BCU receives a crank signal from the ignition switch, an earth path is completed to the starter relay coil,
provided that the security system has been de-activated. If the ECM has not received a valid unlock/ remobilise signal,
the starter relay will be disengaged and the engine stopped. The BCU also receives an engine running signal from
the instrument pack, so that if the ignition key is turned to the crank position while the engine is running, the starter
motor relay will not be engaged.
If the logic conditions are correct to allow starter operation, the completion of the earth path from the starter relay coil
to the BCU energises the coil and the relay contacts close to supply battery power to the starter motor.
When the ignition switch is released from the crank position, the power supply feed from the ignition switch to the
starter relay coil is interrupted and the relay contacts open to prevent further battery feed to the starter motor.
If a communications link failure is experienced, the BCU will be prevented from detecting the 'engine running'
condition and the BCU will default to assume that the engine is not running.
On C0663