BSI

[Stempy]

Am I correct that a BSI unit can't be matched to an engine ECU with a Lexia and would need a specialist service to recode the eprom or is even that not possible?

[CitroJim]

On the Xantia CPH that's the case Stempy, it's a program once only device as far as the Lexia is concerned but potentially a skilled third-party might be able to 'do' the engine ECU to make it work... After all, it's possible to de-program the FAP bits and I believe the immobiliser bits can be programmed out in the hands of a skilled coder.

I would therefore assume the same applied to a BSI, say on an early C5

[wheeler]

Correct, a BSI is a program once only. it cant be reprogramed with Lexia.
It has to be done via the eprom.

[BX]

There are a 3 options that I can think of.
1. Transfer the eprom chip from the original BSI. This is usually an 8pin chip so its easy enough.
2. Load a virgin file into the eprom of the replacement BSI and then configure it with the lexia or a suitable third party tool. This is the best option if the original BSI is totally gaga.
3. Copy the contents of the eprom from the original unit and load them into the replacement. The replacement is now plug and play.

The story is the same for practically every car now. As far as I can see PSA and MB went there first in the 1990s and were followed by everyone else in the new century.

[cachaciero]

Mmmmm..!

The main core program of the BSI may well be write once for a particular car but there must also be reprogrammable areas of the memory else how would you be able to set up individual parameters in it e.g instrument calibration data, (plus other stuff which I know is there but don't come to mind presently .
Question is what requires matching between the injection ECU and BSI? mileage is probably one and security codes is another and are these not resettable with a Lexia albeit requiring specific authorisation codes?

cachaciero

[wheeler]

The milage is not stored in the injection ecu. The security side of it is the only write once only. The immobiliser code can only be written once & it has to match the code stored in the injection ECU & the transponder chip in the keys. Other options & specs are reconfigurable as meany times as you want with Lexia.
This also means when fitting a brand new or virginised BSI you need to be extra careful when entering the security code, especially if your security code contains the number 0, this can easily get confused with the letter O. If you get it wrong the BSI is scrap. I found that out the hard way
Lexia now gives you a warning just before you enter the code to tell you that Citroen security codes never contain the letters O or I, the older versions never used to

[cachaciero]

Interesting the C5 Training Notes I have say that as regards the BSI the Customer Access Code can be entered up to three times after which further programming will be inhibited for 1 minute.
As regards the injection ECU it says that the Customer Access Code can be entered three times after which programming is inhibited permanently.

My take on this is that it would imply that if fitting a second hand engine ECU where the Customer Access Code for the ECU was known then the BSI could be re-programmed using that number or vice versa i.e a used BSI could be re-programmed to the injection ECU Customer Access Code.

However I suspect that what is written is not the whole truth and that in reality once code correspondance between the two ECU's has been achieved then any further attempts to change the Customer Access Code is permanently inhibited in both boxes, I would though expect the system to allow more than one attempt to enter the correct code I suppose three is as good a number as any, yet Wheelers experience is that it is a "one shot" deal which from an engineers perspective is pretty poor design as it makes no allowance for any error.

The one thing to take from this is that if sourcing a second hand ECU then getting the boxes as a pair from the scrapper may be cheaper than paying somebody "to clean " the ECU memory to allow re-programming.(and I would want to see the boxes in the car before agreeing to buy. I have no confidence in the average scrappers record keeping )

cachaciero

[Stempy]

From what I can gather from a specialist they can virginise a BSI but even if they have the code they would be unable to enter it as it has to be able to talk to the engine ECU for confirmation of the correct code and so has to be done attached to the vehicle.

Mine is doing all sorts of weird stuff now including something that will drain the battery over night at random intervals (brand new super duper Bosch battery), odd display error messages, equipment functioning or not as it feels fit, window switches working back to front. BSI reset procedure will partially work sometimes. Strangely no BSI fault codes logged on the Lexia

[wheeler]

Interesting the C5 Training Notes I have say that as regards the BSI the Customer Access Code can be entered up to three times after which further programming will be inhibited for 1 minute.
As regards the injection ECU it says that the Customer Access Code can be entered three times after which programming is inhibited permanently.

The bit your reading about inhibiting for 1 minute sounds like the key learning sequence. When you program a key you need to enter the code first, if you enter it wrong 3 times it stops the key programming procedure for 1 minute before you can try again.
Brand new ECU's & BSI's can definitely only have the security code programmed once.
Like i say a few years ago i found that out the hard way when fitting a new BSI i had the original code card right in front of me the code contained the number 0 but I thought it was the letter O. Once i entered the wrong code that was the BSI scrap.
The reason it can only be written once is security, if you had a few shots at changing it then you could just bring along a pre programmed key & change the codes in the BSI & ECU to suit it enabling the ECU to be unlocked & the car hot wired.