ECU and BCU compatibility

As Cobber suggests it is always good to ask. So can anyone offer some clarity on this please?
There is an engine management unit, a body control unit and a volumetric sensor in a manual 2002/2003 MGTF 135 (Lucas not Pectron).
How many of these three items are coded to each other please and does the ring around the steering wheel also feature in this “linking”?

I’m considering replacing the BCU and clearly don’t want to obtain and fit one and discover it doesn’t work.
If they are coded to each other can pscan re code the system?

In manual for MGTF 2002/2003 for Lucas equipped csr you do not have mentioning of body control unit or BCU. BCU is also called SCU - Security Control Unit because of function it does.
In mentioned manual you have MutliFunction Unit or MFU and Lucas/TRW Alarm ECU called 5AS.

In second half of 2003 MGTF statrted to be equipped with Pektron BCU which replaced both units with one. So instead of MFU plus 5AS you have only one unit -BCU.

In case of 2002/2003 MGTF with Lucas alarm system Lucas Alarm ECU 5AS is paired with engine ECU or Engine Management System as stated in mentioned manual. Remote fobs are paired with 5AS. And that is what is paired in the car.

Volumetric sensor, ring around ignition barrel and MFU are not paired with engine ECU. That means you can replace them without any worry.

However 5AS needs to be paired with engine ECU and that can be done with PScan.
Also remote fobs needs to be paired with Lucas alarm 5AS and that can be done with PScan.



In case of second half of 2003 onwards MGTF is equipped with Pektron BCU. That unit is paired with engine ECU or Engine Management System. Remote fobs are paired with BCU. All of that can be done woth PScan. However do not forget you need barcode with remote fob if you want to pair it with Pektron BCU.
Volumetric sensor and ring around ignition barrel are still not paired with anything and can be replaced without any worry.



In short you cannot replace BCU in your car since you do not have one. What you would like to replace: MFU or 5AS?

Thank you for clarifying that. I have looked in the WSM I have and there is nothing that gives that detail that I can see. In Roger Parker's book "MGF & TF Restoration Manual" there is reference to the 5AS.
I have grasped the importance of the need to match engine ECU to the 5AS.
What I am struggling to identify is anything to do with the connection between the door locks and the 5AS. Clearly there is one.

I am aware that the Pectron unit tends to need the relays associated with locking and unlocking the door locks. So with that thought I am considering what relationship the 5AS has with the door locking arrangement and specifically for the following reasons.

When the door button is going rapidly up and down (machine gunning) it is the locking motor that is driving that action.
The three micro switches in the lock mechanism would not seem to have a bearing on that. One determines if the key has been used, one determines if the door is closed and the other if the internal quadrant has reached its intended position (being uncertain if the switch is normally open or closed I can't comment on its status when the quadrant within the lock is in the unlocked position).
If we start with a door closed and locked condition it would be reasonable to think that the motor will continue to drive the lock open if the fob signals the 5AS to unlock the door until something breaks or the associated clutch continues to function. As the quadrant can only swing between a relatively small arc there is nothing that would permit it to continue to rotate. With that said something else has to tell the motor to change direction and that can only be the 5AS.
If the system requires a micro switch to change condition from open to closed or closed to open and that switch has failed surely the 5AS will continue to send power to the locking motor to continue to rotate in the selected direction. As the quadrant reaches its end position the clutch will slip but it will not drive the motor the other way unless something in the 5AS tells it to.
So what is it? Any ideas will be gladly accepted. It is for this uncertainty that I am considering changing the 5AS

I don’t mean to take this thread off topic but since Roverlike posted the following;
”in case of second half of 2003 onwards MGTF is equipped with Pektron BCU. That unit is paired with engine ECU or Engine Management System. Remote fobs are paired with BCU. All of that can be done woth PScan. However do not forget you need barcode with remote fob if you want to pair it with Pektron
BCU”
I presume the link to the ECU is to cut the power supply or earth so the engine won’t start?
If so could you retain the immobiliser with an aftermarket ECU?
 

MGB281 wrote:

I don’t mean to take this thread off topic but since Roverlike posted the following;
”in case of second half of 2003 onwards MGTF is equipped with Pektron BCU. That unit is paired with engine ECU or Engine Management System. Remote fobs are paired with BCU. All of that can be done woth PScan. However do not forget you need barcode with remote fob if you want to pair it with Pektron
BCU”
I presume the link to the ECU is to cut the power supply or earth so the engine won’t start?
If so could you retain the immobiliser with an aftermarket ECU?
 

Original engine ECU is set to question 5AS or BCU for dedicated paired code. If that code is not present, engine ECU will not work, it will be immobilised. 
However if engine ECU is remaped or aftermarket ECU is used and that questioning sequence for paired code is removed you will be able to use engine ECU without immobilisation as it is not present.
Not to be confused, you still needs remote fobs since 5AS or BCU is still present and it will do its remaining functions of prevention but not the engine immobilisation.

Delbourt wrote:

Thank you for clarifying that. I have looked in the WSM I have and there is nothing that gives that detail that I can see. In Roger Parker's book "MGF & TF Restoration Manual" there is reference to the 5AS.
I have grasped the importance of the need to match engine ECU to the 5AS.
What I am struggling to identify is anything to do with the connection between the door locks and the 5AS. Clearly there is one.

I am aware that the Pectron unit tends to need the relays associated with locking and unlocking the door locks. So with that thought I am considering what relationship the 5AS has with the door locking arrangement and specifically for the following reasons.

When the door button is going rapidly up and down (machine gunning) it is the locking motor that is driving that action.
The three micro switches in the lock mechanism would not seem to have a bearing on that. One determines if the key has been used, one determines if the door is closed and the other if the internal quadrant has reached its intended position (being uncertain if the switch is normally open or closed I can't comment on its status when the quadrant within the lock is in the unlocked position).
If we start with a door closed and locked condition it would be reasonable to think that the motor will continue to drive the lock open if the fob signals the 5AS to unlock the door until something breaks or the associated clutch continues to function. As the quadrant can only swing between a relatively small arc there is nothing that would permit it to continue to rotate. With that said something else has to tell the motor to change direction and that can only be the 5AS.
If the system requires a micro switch to change condition from open to closed or closed to open and that switch has failed surely the 5AS will continue to send power to the locking motor to continue to rotate in the selected direction. As the quadrant reaches its end position the clutch will slip but it will not drive the motor the other way unless something in the 5AS tells it to.
So what is it? Any ideas will be gladly accepted. It is for this uncertainty that I am considering changing the 5AS

I think that you are looking into wrong direction here. 5AS and BCU are doing central locking function. Both are sending signals for motor direction on all locks simultaneously. So if directon of lock motor would be changed from one direction to the other by 5AS or BCU it would be done on both doors in the same time, and not only on one door.
If I understand correctly problem is on one door only, so whatever it is it is done locally on that door only.

How long signal is active for one direction of door lock/unlock I am not sure at this moment. Would need to investigate if that information is available somewhere.

To clarify: -
Initially the experience of “machine gunning” was observed on both doors. As a consequence the doors were locked using the key only until the driver’s door lock was replaced (it was assumed that the driver’s door dictated what the passenger door did or performed).
During the process of preparing for removal of the driver’s door lock a further “machine gunning” was experienced before the battery was disconnected. It is not what instigated that, possibly as a consequence of having the key in my trouser pocket and squashing it as I leant into the car.

Investigation of the removed lock prompts further questions (see other topic relating to superlock). Simply put none of the three micro switches appear to directly affect any “message” to the 5AS when seeking to unlock.
In order to “machine gun” the basic door lock motor needs to rotate in both directions (there is nothing to drive either the door button or the door lock key electrically).
So somewhere within 5AS there must be something to tell it to reverse the motor’s direction (and as there is nothing to restrict movement from superlock to unlocked superlock must be irrelevant in this context).
So my theory is that the 5AS must be failing.
Ill be delighted if there is another explanation.

5AS failing is very rare situation and must say that failed central locking in case of 5AS is possible in case of fried printed circuit board which I've seen, but never saw 5AS failing in such circumstance to give "machine gun" problem. Always it was door lock problem, not 5AS problem.

Do not forget that one of the switches provide information of sill up or down and the other of the switches provide information of drivers door closed or not.

Drivers door sill can be put up or down by hand and by that you will trigger central locking or unlocking of both doors. So if that switch is not behaving as it should it will trigger 5AS to react.

If 5AS is failing I would expect for new lock to behave in same manner with "machine gun" because 5AS is failing and it is not replaced. Only door lock is changed.

I accept that 5AS has a higher sense of reliability than Pektron.
Let’s just consider the situation for a moment. Prior to locking the car there was no movement of the key (nor prior to attempting to unlock with the fob), so the plunger operating that micro switch was not disturbed and it stayed put.
After examining the mechanism there is no apparent deficiency (wear) in the arm that tells the system that the door is closed (and if there was what difference would it make?).
The operation of the fob to lock the car and the subsequent motor movement of the quadrant within the mechanism sweeps the quadrant past a micro switch (it is not known if that switch recognises the first locked position or the superlocked position.
However, when the fob is engaged to unlock the door it must surely send a signal to the 5AS to open the lock. 
Logically there is only one micro switch involved that is the one swept by the quadrant and I cannot see anything that would change the current flow direction through the motor to make it turn one way then the other unless the 5AS switches the current.
If I’m wrong I’ll be pleased for someone to explain why/how.

Roverlike wrote:

MGB281 wrote:

I don’t mean to take this thread off topic but since Roverlike posted the following;
”in case of second half of 2003 onwards MGTF is equipped with Pektron BCU. That unit is paired with engine ECU or Engine Management System. Remote fobs are paired with BCU. All of that can be done woth PScan. However do not forget you need barcode with remote fob if you want to pair it with Pektron
BCU”
I presume the link to the ECU is to cut the power supply or earth so the engine won’t start?
If so could you retain the immobiliser with an aftermarket ECU?

 

Original engine ECU is set to question 5AS or BCU for dedicated paired code. If that code is not present, engine ECU will not work, it will be immobilised. 
However if engine ECU is remaped or aftermarket ECU is used and that questioning sequence for paired code is removed you will be able to use engine ECU without immobilisation as it is not present.
Not to be confused, you still needs remote fobs since 5AS or BCU is still present and it will do its remaining functions of prevention but not the engine immobilisation.


My 2003 TF (Lucas fob) has now an ECU sent by K-Maps, not the original one (happy with the remap, BTW)
Does it mean the immobilisation has been erased?
I was thinking of having it suppressed, it would be a nice addition if it has already been done
 

Red110 wrote:

Roverlike wrote:

MGB281 wrote:

I don’t mean to take this thread off topic but since Roverlike posted the following;
”in case of second half of 2003 onwards MGTF is equipped with Pektron BCU. That unit is paired with engine ECU or Engine Management System. Remote fobs are paired with BCU. All of that can be done woth PScan. However do not forget you need barcode with remote fob if you want to pair it with Pektron
BCU”
I presume the link to the ECU is to cut the power supply or earth so the engine won’t start?
If so could you retain the immobiliser with an aftermarket ECU?


 

Original engine ECU is set to question 5AS or BCU for dedicated paired code. If that code is not present, engine ECU will not work, it will be immobilised. 
However if engine ECU is remaped or aftermarket ECU is used and that questioning sequence for paired code is removed you will be able to use engine ECU without immobilisation as it is not present.
Not to be confused, you still needs remote fobs since 5AS or BCU is still present and it will do its remaining functions of prevention but not the engine immobilisation.


My 2003 TF (Lucas fob) has now an ECU sent by K-Maps, not the original one (happy with the remap, BTW)
Does it mean the immobilisation has been erased?
I was thinking of having it suppressed, it would be a nice addition if it has already been done

 

You can ask K-Maps if that part of code interrogation is removed.

Delbourt wrote:

I accept that 5AS has a higher sense of reliability than Pektron.
Let’s just consider the situation for a moment. Prior to locking the car there was no movement of the key (nor prior to attempting to unlock with the fob), so the plunger operating that micro switch was not disturbed and it stayed put.
After examining the mechanism there is no apparent deficiency (wear) in the arm that tells the system that the door is closed (and if there was what difference would it make?).
The operation of the fob to lock the car and the subsequent motor movement of the quadrant within the mechanism sweeps the quadrant past a micro switch (it is not known if that switch recognises the first locked position or the superlocked position.
However, when the fob is engaged to unlock the door it must surely send a signal to the 5AS to open the lock. 
Logically there is only one micro switch involved that is the one swept by the quadrant and I cannot see anything that would change the current flow direction through the motor to make it turn one way then the other unless the 5AS switches the current.
If I’m wrong I’ll be pleased for someone to explain why/how.

When fob sends signal to 5AS lock will be turned into unlock position and microswitch you are describing will be in unlock state. However in the same time sill is taken into up position where second microswitch is placed, isn't it? That second switch is disturbed at that time. At that moment proces of getting lock to unlock state is over and 5AS is not providing any signal any more.

However this microswitch which is disturbed by the sill is the one that sends signal to 5AS that sill changed position from up to down or vice versa. If that switch is playing and is changing state without being told to do so, then it will start sending 5AS information that sill is moved up and down and to send current into door lock to activate it for closing and then opening and then closing etc.

In your description you did not take this second switch into account which is inevitable disturbed with unlock operation by the sill movement.

And then, since sill microswitch is interconnected with third microswitch, that microswitch also changes state.

So, with one action all three microswitches are disturbed at once and change their respective state.