There are two functional aspects being mentioned here which seem to be getting a bit mixed up and for clarity i would like to try and explain them better.
The first functional aspect is the dis arming of an Alarmed BeCM via diagnostics.
This is possible, however it can only be done on the very very latest BeCM versions (PAM36) or later and you have to know the EKA code it is programmed with for it to work.
The latest T4 software did provide this function and it is of course therefore included with our standard SM022 BeCM software module which i might add costs 112 GBP as a seperate MV module and is included with all SV P38 Kits.
See the bit at the bottom of the settings section of our SM022 help page
here.
https://www.blackbox-solutions.com/shop/help/SM022.html
This function simply dis arms an armed BeCM and nothing more, and frankly is not much use, as if you happened to have a BeCM fitted with the right version, and knew for sure what the EKA code was, you can do this with the Key in the door lock.
Those only familiar with the small handful of settings capabilities the the TestBook / T4 provide might also notice all the other settings possibilities of this module, allowing for example the setting of the Instrument Pack Language to French. This is possible by changing the Market to French with a TestBook / T4 but then that also means you set loads of other options such a LHD etc.
The second functional aspect is unlocking a locked BeCM, This has nothing to do with the armed state, the version, or if you know the EKA code or not. It simply cannot be done by Testbook / T4 or indeed any other manufacturers equipment except BBS's.
To do it, not only do you need to have our hardware but you also need to purchase the special SM035 direct CPU access module which is not cheap as it is not intended for private owners.
This is the holy grail and provides unlimited access and capability no matter what, but here is a quote from the information we provide on it that explains its usefulness much better.
Although there is already a Module (SM022) which provides full diagnostic access to the BECM (Body Electric Control Module) fitted only to the P38 Range Rover (1995 to 2002 Model). There are a number of core pieces of information that the BECM is by design, unable to reveal through the normal diagnostic connection under the control of a one time usage software lock, and also the ability to change some others. This limitation effectively prevents re usage of salvage or otherwise used BECMs as well as trial substitution. It also forces replacement of the BECM in many circumstances when there is actually nothing wrong with it. Despite high development costs, and expectations of low volumes of sales, we have produced this module which allows for direct connection of a Vehicle server to the Microprocessor of the BECM and thereby direct read and write access to all stored memory in it. Besides offering a full memory save as Hexadecimal in a HTML page capabilities as well as the ability to re load and write pages back, which can be handy for those wanting to experiment with swapping bits round, this module also provides a settings page identical to the SM022 one except all of the previously empty boxes such as EKA (Emergency Key Access) code and the Fob Code which is used to validate the correct remote key fob are now populated. In addition it is now also possible to alter previously read only values such as Odometer (Miles / Kilometres travelled) and VIN numbers. Naturally of course the one time lock function can also be reversed. In addition the State of both the Alarm and the EKA lockout delay can be read and altered which is very useful as in an Armed or EKA locked out BECM there is no way to be able to communicate with it through the diagnostic connection and if there is no way to disarm the BECM it is otherwise a catch 22 situation which is usually circumvented only by replacement with a new BECM.