Citroen XM - lost contact with ECU

[Mateusz]

Hello
Have strange problem, got Citroen XM mkII 2.1TD 1997. after 2 months parking my car lost connect with computer.
Lexia cant connect with Lucas Pomp and Hydroactive suspension. Immobilizer (code keyboard) throw me errror - no connect with ecu. Also automatic gear box display stopped showing actual gear. That lots of problems i never got before lets me think that could be lost ground. I cleaned all conections and fixed ground connection on both fenders. Thats doesnt help. My knowledge about this car is not big like in my whole country, so maybe someone here could me help?

[white exec]

There are some members here with XM, but the best place to post this is on our sister site specialising in XM.
This page will let you Register and post...
http://www.club-xm.co.uk/forum/ucp.php?mode=login

When you do post there, give details of what happens when you switch the IGN on - what lights up (dash, displays, etc), and what works (eg radio, lights...) and what doesn't. This info will help.

[GiveMeABreak]

Have you charged the battery up fully after you left it parked up for 2 months? If the battery has gone flat, the ECUs have lost power. I'm not sure how you started the car, but I would remove the battery, and fully charge it up, then when you connect it leave it for 5 minuted before attempting to start it to allow the ECUs time to initialise.

[Mateusz]

Battery was charged.
Car won't start

[GiveMeABreak]

This procedure is for the XUD11ATE and explains how to unlock it in several scenarios:

Vehicle with an "ADC" keypad:

Scenario 1: Locking and unlocking of module possible

Unlocking Procedure

1	Switch on the ignition
2	Unlock the module by entering the user code Do not switch off ignition
3	Unplug the connector linking the module to the engine harness (the stop electrovalve is then no longer supplied): (4-way black)
4	Switch off the ignition
5	Note down the user code on the pump

This procedure:

• Ensures that the module is really unlocked
• Is the only one permitting a pump check on the bench (without exchange of the module)

Bench testing the pump
With the module unlocked, the pump can be operated after having supplied the electrovalve via the connector fixed to the pump (4-way black):

• Terminal 1 --> +12V
• Terminal 4 --> Earth

2nd case: Locking and unlocking of the module impossible
CAUTION: Note down the user code on the pump.

Vehicle equipped with a transponder
Unlocking procedure:

• Open the bonnet
• Lower the driver’s window
• Close the driver’s door
• Switch on the ignition
• Wait for the transponder warning lamp in the instrument panel to go out
• Switch off the ignition
• Disconnect the ECU within 5 minutes

[white exec]

Before doing any of that, I must ask - and this is important -
When you switch on the IGN:
- what dash lights light up?
- does the left-hand (matrix) display show or do anything?
- on the keypad, do you get Red, or Green or Red+Green, or any audible beep? Does either LED flash repeatedly?
- on the keypad, what do you get when you enter the correct code?

Warning: Disconnecting the keypad incorrectly can result in engine being permanently unable to start.
Make sure you have the correct Code (to start) written down somewhere.

If you have an Inertia Switch under the bonnet*

make sure it is pressed down (= reset). *This was deleted on late XM diesels.

[xantia_v6]

The range of symptoms in the first post would indicate to me that the problem is a lack of power supply to several ECUs, or a wiring fault. Have you checked for rodent damage to the wiring?

You may need to probe the wiring near the ECUs to check that the static supply voltages are all correct.

[white exec]

This is why we need to know what happens when IGN is switched on, and what the keypad shows.
Does sound like a central failure of power.

These might be of help in finding your way around:
http://citroen.tramontana.co.hu/en/the- ... am-project
http://citroen.tramontana.co.hu/en/elec ... -part-list

[Mateusz]

I dont have Inertia crash switch.
No, i dont check wires. Dont have device and schema.
Decided record video to better shown problem:

[white exec]

Thanks for posting the three videos: a big help.
You are getting Red + Green on the keypad when IGN is switched on.
That indicates a fault.

Check out fuse F31 on the passenger cabin fuseboard. It may not have blown, but may not be making good contact with its fuseholder contacts. This causes Red+Green, and an engine that will not start.

The failure to start, and Red+Green fault lights, suggests that the brown Bitron double injection relay (#807) is not being powered up properly, via F31 (direct from battery) and/or via IGN switch. You'll need to look at Gabor's circuit diagram (Engine, 2.1TD) to see how it connects.

Everything else in your video looks good, except the LH (matrix) display, which has lost many of its pixels.
That is fixable.

Beautifully clean engine bay; you obviously look after her well!

[Hell Razor5543]

Even if the fuse has not failed what can happen is that a tarnish can build up on the fuse and fuse holder contacts (I have had this happen to me). Use a decent contact cleaner on the contact points and plug/unplug the fuse several times. This should, with a bit of luck, scrape the tarnish off and allow normal service to resume.

[Mateusz]

I repleaced Fuse 31 (10A) to another but without results.
I dont have brown bitron attached outside computer box. Maybe its moved into box and that could be this black bitron (3)
In my version its looks like that:


Yah, left display waiting in queue to fix. Now i have bigger worries

[white exec]

Yes, #3 is the Bitron double relay (injection relay).
The purple one (#4) on the right is the AirCon relay.
Both relays normally live on the front outside face of the ECU box.

Using Gabor's 2.1TD circuit diagram, check that the Bitron relay is getting correct supplies - permanent live, IGN sw live, and Gnd. The pin numbers in your photo correspond exactly to the 15-way connector shown in Gabor's diagram.

[Mateusz]

thanks for the clue. I check it in multimeter soon

[Mateusz]

Have already checked pins, looked only where is power.
To test i unplug all connectors from computer box like on the picture


First test i checked when incognition OFF
here is result:
Fuse 31 - powered
#1 Lucas epic computer - No power
#2 Valeo computer - No power
#3 Bitron - Powered pins: 8 , 11 , 14 , 15
#4 purple relay - No power
#5 Cruise control - No power

Second test when incognition ON
Fuse 31 - powered
#1 Lucas epic computer - Powered pins: 11 (midle line counted from left, picture bellow)
#2 Valeo computer - No power
#3 Bitron - Powered pins: 2 , 8 , 11 , 14 , 15
#4 purple relay - No power
#5 Cruise control - No power

Third test i plug in only #3 bitron and tested:
#1 Lucas epic computer - Powered pins: 11 , 18 (midle line counted from left, picture bellow)
#2 Valeo computer - No power



Noticed when i unplug computers and turned incognition ON - check engine control not appear