P1668 PASSIVE IMMBILISATION: ONLY with replacement plip/keyfob

robertofollia

Well-known member
Aug 3, 2005
560
2
My home is where my Disco is
So I lost my wallet with all documents and one of the D2 keys (plip). It came with 2.
I had a replacement plip with barcode from a Rover 75.
Programmed it to the BCU using Nanocom. No problem. BCU recognised it
Locks, unlocks and disables alarm, but when turning key to pos II the LED lights statically and no crank no start. The only way is to take key, press "unlock" and within 30 seconds insert key and start the car.

With the remaining handset/keyfob/plip this does not happen
According to RAVE "Valeo BCU Unit", when inserting the key and turning it to pos II, there is a coil in ignition barrel which energises, sends a code to the plip and the plip responds (as if it were a transponder, but D2 plips don't have this chip/transponder) disarming the passive immobilisation.
In case the connection is lost the LED stays lit up and you have to remove key, press unlock and within 30 seconds insert key and start car"
Here is an excerpt from technical academy

Body electrics
Technical Academy Vehicle security 29
03-11-LR-W: VER 1
Door lock actuators
The door lock actuators are an integral part of the door latching assembly. They all have the facility
to ‘ superlock’ (superlocking is when the inside door handles and sill buttons are disabled). The
BCU controls the driver’s door separately from other doors. This enables functions like single point
entry and key access. All the door lock actuators are controlled by the BCU via the intelligent
driver’s module (IDM).
TestBook can drive all the door actuators to test their functionality. It can lock, superlock and
unlock all the doors.
Passive coil
The passive coil is located around the ignition key barrel. When the BCU detects that the ignition
key has moved to position III and the vehicle’s immobilisation system is activated, it will supply a
voltage at a frequency of 125 kHz. This voltage powers the passive coil. The coil will produce a
varying magnetic field, which will radiate within close vicinity of the ignition key barrel. The
magnetic field transmitted by the coil triggers the remote transmitter to transmit a remobilisation
signal."
Passive immobilisation
Passive immobilisation prevents the vehicle from being started unless a correctly programmed
remote transmitter key is used to start the vehicle. This system works whether or not the driver
sets the security system into an active state.
The BCU immobilises the engine 5 minutes after the ignition has been switched off, providing the
drivers door is not opened. The BCU will immobilise the engine 30 seconds after it detects the
driver’s door opening.
Immobilisation is achieved by the BCU not transmitting the code to the EMS ECU. This code is
needed to allow the engine to continue to run after the initial start-up sequence. If the BCU or ECM
is replaced, this code will require synchronisation with the new unit.

Passive remobilisation
The BCU has a function that will automatically remobilise the engine when the ignition is switched
‘ on’, providing the BCU receives a valid code from the remote transmitter. When the ignition is first
switched ‘ on’, and the vehicle is in an immobilised state, the BCU powers the passive coil located
around the ignition barrel.
The passive coil produces a magnetic field, which excites the circuitry inside the remote
transmitter. The transmitter then sends a remobilisation signal to the BCU. If this system fails and
the BCU does not receive a valid signal it will stop energising the coil after one minute of operation.
The driver of the vehicle will then need to either press the unlock button on the remote transmitter
or enter the EKA code to remobilise the engine.
Both engine immobilisation and remobilisation are transparent to the driver of the vehicle providing
the system is operating correctly.
Depending upon market configuration and vehicle options, the engine immobilisation features of
New Discovery may be allowed to be switched off."

There is a wonderful TSB by Chris St Louis here but only deals with BCU replacement, as Testbook (after that T4 and later IDS) can do nothing about it

Here ther's a link to Technical acdademy body electrics in pdf format (just 48 page) which deals with that (the complete version of what I copy pasted)

Besides ordering a new BCU or sending it to callrova in UK which are the only ones who can reprogram and rewrite BCUs, any other way?
-As disabling passive immobilisation
-Getting a D2 plip (not the one brand new from rover 75) and program it and see what happens
-Or spend the rest of my driving days having to press unlock twice (1st time for entering the car and 2nd time for starting) in order to drive the car

Best regards
Robert
 
Last edited:

discostew

Well-known member
Sep 14, 2010
7,774
1,045
Northern Illinois
T4 is hard to find these days for sure. But lots of people still have what we call the Handheld. It slides into a docking station on the T4 interface. Those never seem to quit and it might be able to help with the security issues. I have both a T4 and the handheld. Where are you located?
Going by memory I think you can tell the vehicle it no longer has immobilization or maybe just learn the code. I don't think the key is involved in the security handshake, cause lots of people are driving around with just key blanks cut from a hardware store. I think that switch in the key barrel just tels the security system the key position has changed.
 
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robertofollia

Well-known member
Aug 3, 2005
560
2
My home is where my Disco is
Hi. Thank you. Sadly I'm across the pond (southern Europe,Spain) so it's imposible to get hold of yout t4.
Unless i've done something wrong programming the new fob, only the remaining old one disables passive immobilisation.
The new one requieres an additional "unlock" button press. Does not Matter which of the 2 fobs are used to unlock the car
As soon as the "new" one is inserted and key turned to II the led lights Up static and no start unless I press unlock again.
But if I don't do that and simply remové the "new" fobs and insert the old one in ignition barrel and turn It to pos.II, led extinguishes and starts 1st time.
I must have done something wrong programming or the fob is not appropriate.
Best regards
 

robertofollia

Well-known member
Aug 3, 2005
560
2
My home is where my Disco is
Hi all,
found the answer in Aulro.
It happens that D2, BMW Mini 1st gen and Rover 75 use the same PCB and chip in remote.
That means you can successfully (as long as you have barcode or chip sticker), program and pair The Rover 75 or Mini 1st gen remote to a D2. It will lock, unlock and disable alarm. But, unless you disable passive immobilisation, you wont be able to start the truck as it will be immobilised (you will need double press the unlock button)
In page 4 there is a pic showing the additional component the D2 remote has, the one that reacts to the coil in ignition barrel and communicates with BCU, disabling immobilizer
Best regards