Hello Dean,
Here is some info from Rave.
If you find that after entering the EKA code, then you have crank & no start, you will need to find the security code in the engine ecu then copy it into the body control module. If you have not unlocked the body control module by using the EKA or from the key being recognised in the ignition barell, then you will get misleading information in the body control module.
"SECURITY/CENTRAL LOCKING S3
CIRCUIT OPERATION 5
Passive Immobilisation
The following conditions will passively immobilise the
vehicle:

30 seconds after ignition has been turned off and
the driver’s door has been opened.

30 seconds after ignition has been turned off, the
key removed, and the driver’s door has been
opened.

10 minutes after ignition has been turned off and
the key removed (without opening the driver’s
door).

The handset becomes desynchronised (or with
an improperly functioning handset).
The vehicle can be mobilised by any of the following
methods:

Turn the ignition on (The handset must be func-tioning
properly and within close proximity to the
key!)

Press unlock button on the handset

Enter EKA code
NOTE: The vehicle will remain immobilised by
attempting to turn the ignition on with the handset
detached from the key ring (or with an improperly
functioning handset).
If the handset becomes desynchronised (or is
functioning improperly), the engine will be passively
immobilised. If an attempt is made to start the
engine, the message “Engine Disabled, Press
Remote” will be displayed on the message centre. To
mobilise the engine the EKA code must be entered
and the handset (when functioning properly)
resynchronised.
Passive Immobilisation Coil (Z270)
A magnetic field is generated by the passive
Immobilisation Coil (Z270) contained in the steering
column. This field excites a receiving coil in the
handset causing it to transmit a mobilisation signal to
the BeCM. If the BeCM does not receive this signal
from the handset, the vehicle will remain
immobilised.
Handset Transmitter Resynchronisation
The Theft Alarm Unit (Z163) will remain
synchronised with the handset unless:

The handset’s batteries have been removed.

The vehicle’s battery has been disconnected.
NOTE: All handsets must be resynchronised when
the vehicle’s battery has been disconnected.
A handset may be resynchronised by performing a
key lock, or unlock, on either front door within 30
seconds of performing a remote lock, superlock, or
unlock function. The BeCM uses the change of state
of the CDL Switch to initiate resynchronisation.
Emergency Key Access (EKA)
EKA is used to disarm the theft alarm and mobilise
the vehicle in the event of a handset failure. This is
possible through a series of locks and unlocks with
the key in the driver’s door lock cylinder. With the
vehicle locked and the alarm armed, turn the key the
required number of times according to the following
sequence:
1. To enter the first digit, turn the key the required
number of times to the unlock position.
2. To enter the second digit, turn the key the re-quired
number of times to the lock position.
3. To enter the third digit, turn the key the required
number of times to the unlock position.
4. To enter the fourth digit, turn the key the required
number of times to the lock position.
5. Turn the key to the unlock position to unlock the
doors, disarm the alarm, and mobilise the ve-hicle.
NOTE: The key must be fully turned to the rest and
lock/unlock position each time.
After 5 wrong attempts, you must wait 10 minutes."
Hope this helps, Regards,Andrew