SPotted on Linkedin FREE 2.5TD Estate in Kent/Surry border

[CitroJim]

As far as I know, the code is stored in the ECU. This is true of at the very least the 1.9TD and TCT as I've conducted experiments on scrappers to prove the case.

I've not done the same on a 2.5TD but I'd be amazed if it was any different...

Normally the keypad is disabled by initially disconnecting it with the engine running. the ECU then detects a communications error with the keypad and this because of this it remains indefinitely unlocked. Reconnecting a disconnected keypad without knowing the code will lock the ECU again.

This 'disconnect whilst running' strategy appears to work for many ECUs but not for the 2.0TCT for some reason. It may not work on others and perhaps not on the 2.5 but I've no experience sadly.

John (xmexclusive) is your man for the absolute facts and truth of all this!

You should be OK swapping ECUs for one with a known code I'd have thought.

So, your keypad is connected then? Otherwise you'd not get any lights at all. Red and green on at the same time indicates a communications error between the keypad and ECU.

I'm not quite sure how it's been disabled if the lights come on but there's no need to enter a code...

[endorfin]

From my own experiences with my own 2.5, I deactivated the need to enter a code without having to disconnect the keypad, I followed the instructions I was given by this forum way back where I had to enter a sequence on the keypad and enter my code to deactivate the need to put in a code every time. All I need to do is turn the key, the green light comes on and car starts. I assume this has what has been done with this one as well.

There is definitely some sort of fault because in the instances when both red and green lights come on, the glow plug light stays on indefinitely. When it's working correctly and the red light goes out and green stays on, the glow plug light operates as normal. When I came to pick up the car, Len had someone in the process of removing the on board dvd player fixed to the roof and there were thick electrical cables snaking into both sides of the dash so it's possible that this has caused an electrical fault somewhere?

The ECU number on the car is 9623191980 - I don't know the code. The ECU number on the spare ECU I have is 9622846080 and I know the code. Both are from M reg 2.5's. I've no idea how to tell if they are compatible.

[endorfin]

I think I've just realised I'm looking at suspension ECU's? Which one is the ECU that controls anti theft?

[messerschmitt owner]

This 'disconnect whilst running' strategy appears to work for many ECUs but not for the 2.0TCT for some reason. It may not work on others and perhaps not on the 2.5 but I've no experience sadly.

Jim

that explains why, when I disconnected the keypad last year when the car was running (2.0TCT) it automatically died on me and would not start until reconnected again.

Didn't try it again. I assume that the most likely code is the one I mentioned (and the one in the manual), as most owners are too lazy to do anything else - and if I was disconnecting I would have set to default.

Let's face it, only a certified nutter would steal a Citroen XM nowadays.

[xmexclusive]

Largest ECU marked BOSCH.

On a 2.5 code is stored in the ECU.
Move the ECU to another 2.5 and you also move the code.
Early and late 2.5 ECU's are not interchangable.
I can read the codes and reset these ECU's to factory.

Have not got a list of the Citroen ECU numbers to hand.
The emmissions standard marking should identify though.
Large marking above the Citroen number and variant number after the first bar code.
Early ECU's - L variants L17 or L18.
Late ECU's - L3 variants L3.16 or L3.17.

The first few L17 ECU's were coded to use 0001 as the garage code.
Later L17's, L18's and L3.16's were coded to use 1111 as the garage code.
L3.17's have a user selectable garage code as well as user selectable immobiliser code.
These last ones can be a real pain if both codes are lost.

Some L18's are coded from factory with automatic plip bypass of the keypad.
If car unlocked with plip gives you 1 minute to start the engine before keypad code is needed.
This is by far the best version of the 2.5 immobiliser setup.

John

[endorfin]

Found the proper ECU in the garage, it's a L18 6923 9832, I know the code for this (at least I hope so!) and the one on the newly acquired XM is L17 6923 1591 previous owner deactivated the need for a code and has forgotten it - I assume these are interchangeable?

How do you access the ECU's John, I presume they need to be opened up to access the EEPROM?
It's not something I have any experience with, would be useful to be able to recover or put a new code in the L17

[xmexclusive]

The numbers 6923 9832 are part of the factory information, not part codes.
Your L18 should have Bosch 0 281 001 212 near the top of the label (Bosch part code) and
96 237 486 80 at the bottom (PSA part number).
EEPROM's are soldered to the main pcb and cannot be read insitu.
I cut them out to read them (deoldering risks altering contents).
Then programme new ones to reset and rebuild the boards.
I have used L18 and L17 (both types) in the same car without problems.

John

[endorfin]

help

I have the code for the ecu now. I need to get OUT of automatic mode, entering the correct code and C0C does not work. it's the d/n keypad but I have a S keypad too

[Dieselman]

The code is in the ECU.

Why not just disable the keypad when the light goes green?

[xmexclusive]

First try after ECU swapping or powering down should not be taken as the final working state.
When I first started swapping 2.5 ECU's this confused me no end.
Often the green light would appear and no code was needed to start the car.
Tried again later and got the red light and needed the code.
If you have recently unplugged the ECU or disconnected the battery then do not
use the engine running/keypad unplug method until you are certain you do not have a false green.

I eventually put this down to the two Microprocessors powering up in the wrong order and so bypassing the security check.
Normally the ECU is powered even with the ignition off so the Micro's are already running and powered.

If one of the cars has a Immo wiring fault then the ECU may well behave differently in a car without faults.
COC was dropped during the various Citroen Immo changes (at least 6 changes on 2.5's 1994/1996).
The changes involve ECU's, keypads and wiring.
There is no exhaustive list of what works and what does not.
Tried enough of the combinations to be able to sort my 2.5's.
Known state ECU's and working with known condition cars was my method.
Too many unknowns with what you are trying for me.

John