Xantia HDi Engine ECU Swap - Anyone with experience of removing ECU terminals from ECU connector too?

[Rhothgar]

Hi all,

Hope you're all having a good weekend.

I am about to set off to go and collect a Xantia ECU, replacement Bitron Relay and Diesel Pressure Gauge on loan from a forum member.

I believe he has successfully swapped an ECU between cars without any frustration.

So, having read quite a few forum posts on this, I am a little confused as to what the BSI unit is which keeps getting referred to? Is that actually the Body CPH? If so, I am sure he has said he has swapped out just the ECU with no issues.

So presumably I will need to reprogramme my only key to the new ECU.

If the ECU swap is successful, then I will buy one off a forum member hopefully or Ebay.

What would I need to purchase one that will not give me any trouble? The confidential code or proof of purchase stating VIN number so Citroen will sell me the confidential code.

Just beginning to wonder what the pitfalls are going to be going down this route?

Also, I spent about 2 hours faffing about trying to remove wire terminals from the ECU connectors to check and clean them. In all that time, I managed to remove the same one several times, the one from Pin 56, which wasn't the one I need to remove but used for practice. When I moved onto Pins 50, 86, 87, 88 which do need careful examination, I couldn't get one out.

Does anyone have any photos of how the different types of terminals look so I decide the best angle of attack. The translucent plastic ECU connector looks as though it can be taken apart but I have NO idea how to do it and I am just going to end up breaking something else at this rate.

[Rhothgar]

Well. I’ve put ECU in and it started first time.

Switched it off and it won’t start again.

[Rhothgar]

Got Lexia plugged in and I can’t even check fuel rail pressure or any other parameters.

I’ll do some more reading up but I’m not sure I understood it fully earlier.

I don’t have confidential code for my car but I actually bought it 2nd hand from a guy who worked at Citroen who was going to scrap it.

When I buy a replacement 2nd hand ECU do I buy the code for my VIN or for the one of the car the ECU will come from please?

[wheeler]

The ECU, CPH & transponder chip are all a matched set. If you use a second hand ECU on its own it wont work. Im guessing it was in an unlocked state to let it fire up then it locked again.
Are you getting a flashing immobiliser light now?
If you wanted to add keys in the future you would need the code from the donor car.
To get the code without the VIN on CAN cars is easy but on an older system like this you need to desolder & read chips from the ECU & decode it from that.
You can have experts remove the immobiliser from the ecu so its unlocked. Again requires chip removal from the ECU.

[wheeler]

The Xantia was never fitted with a BSI. Mk2 models have a the CPH which was a very primitive form of a body computer.
They will be mistaking the CPH for the BSI.
As for the ECU plug, you have the 88 pin?
I cant remember that one off hand but cant think of a PSA ecu plug that isnt fully strippable, in fact almost all connetors can be fully stripped down, there are a few exceptions of corse like some of the resin moulded ones.

[Rhothgar]

The ECU, CPH & transponder chip are all a matched set. If you use a second hand ECU on its own it wont work. Im guessing it was in an unlocked state to let it fire up then it locked again.
Are you getting a flashing immobiliser light now?
If you wanted to add keys in the future you would need the code from the donor car.
To get the code without the VIN on CAN cars is easy but on an older system like this you need to desolder & read chips from the ECU & decode it from that.
You can have experts remove the immobiliser from the ecu so its unlocked. Again requires chip removal from the ECU.

Hi Wheeler

I witnessed Andrew put it in his car today and his started then I started mine when I got back. Thing is is the ECU he has loaned me came from a Xantia where the last digit of the VIN number was only 1 different so the car it came out of was either one behind or one in front of his other car on the production line.

Mine is on a X so no idea why it started.

Yes the transponder light is now flashing continuously.

Mine is indeed the 88 pin and I can upload a picture later of the connector.

I guess if I plugged my ECU back in then swapped them out whilst live after the handshake has occurred, it would probably fire up again.

I've watched a couple of videos and it seems one way is to remove the immobiliser chip from my ECU and solder it into the replacement ECU. It still needs to be read and written. Need to look into this a little more.

There is also this MPPS reader but I think that is merely for reading the existing ECU and writing that to the donor ECU.

I'm clearly not out of the woods yet.

I wonder if Jim at EasyDiagnostics sells a cheap solution to the problem.

Remove the immobiliser chip in itself would be a relatively simple desoldering task but it's what you do with it after that counts.

[wheeler]

From how I understand it if you desolder the chip that holds the immobiliser data & resolder it into another ECU then that ecu should now start your car with no programming needed.
Identifying the chip is another matter, again from what i gather it is usually an 8 pin chip.

[Rhothgar]

Yes. It is an 8 pin chip.

I am going to get an ECU and first try programming key with Xtools X100 back to new ECU before I get serious with chip desoldering.

[wheeler]

Not sure I understand what you are going to do but even with the X100 you will still need the security code to program any keys to the car. The ECU & CPH must also be a matched pair. You wont be able to reprogram a transponder chip that’s already been used to a different CPH/ECU.

[Rhothgar]

Not sure I understand what you are going to do but even with the X100 you will still need the security code to program any keys to the car. The ECU & CPH must also be a matched pair. You wont be able to reprogram a transponder chip that’s already been used to a different CPH/ECU.

What you say is exactly my understanding from reading a fair few forum posts yesterday but my mate does say the X100 may do it, it may not. He also has full master and slave Kess and Ktag systems amongst others.
He spent £12000 for the full kit plus many other solutions. He is unsure if X100 will do it but he says there's no harm in trying in the first instance (which there isn't other than it will waste a bit more time getting the car sorted).

I'm sure he said he thinks one of them should be able to read confidential code from the ECU.

Next best solution is probably desoldering immo chip and putting into replacement ECU. That should be a straight exchange theoretically.