Xantia 2.0HDi Non-Start - Lexia Observations and NOW Screenshots!

[wheeler]

How i would proceed next with this.
Check all supplies & earths at CHP and engine ECU, check the supplies & earths with a load like a filament bulb, a voltmeter can show a decent voltage but there is not enough current.
check the communication wires between ECU & CPH, again under load.
In my experience 90% of immobiliser faults (either keypad or transponder) on that era of Citroens is caused by power supply or earth problems to the injection ECU or double relay. Try removing & cleaning main earth points in the engine bay.
Yes I would agree that is sounds like the key is synced with the car ok.

[Rhothgar]

Thanks Wheeler. I will revisit what you have said above at some stage.

I’ve been going through the diagnosis factory manual and scratching my head.

Get this! I jumped pins 4 and 6 on the driver’s door lock and the car started and ran for more than the 1 second it has been doing. Maybe 2-4 seconds then died.

Battery now low though....

[Rhothgar]

For the record else I’ll forget!

I’ve stripped out all door wiring because I’ve effected a repair on it before to do with windows.

I can see no issues with the wiring to Pins 4 and 6 of the driver’s door switch.

6.1.3 Door pillar switches (Diagnosis Factory Manual) states:-

While the CPH is scanning the doors:

U ~ 9V = door closed
Otherwise:
U ~ 1V
U < 1V = door open

Key not in ignition
Door Open, I get 0V.
Door closed, I get 9.65V

Key in ignition, on Accessories and in Start position:-
Same results.

Under no circumstances do I see 1V

This is all tested by piercing two wires in the door.

[wheeler]

Pins 1 & 3 on the yellow CPH plug are the drivers & passengers door switches inputs. Not sure if the wire earths when the door is opened or closed but you should see the status change when it is opened or closed.

[Rhothgar]

It is impossible to test with the CPH connected. Not without buying some ultra short probes or something that can be plugged into the connector because it is SO inaccessible.

If I knew connector terminal sizes, I am getting to the stage where I would make up some break-out leads! Be quicker and easier.

I am getting absolutely nothing at CPH other than supply to the CPH+ permanent Pins 4 and 13 (15 way black connector). Battery voltage.

Supply to the CPH+ permanent outputs. Pins 1 and 13 (15 way black connector). Battery voltage.

For instance, transponder analogue module says ECU disconnected (which ECU , Engine or CPH). Should get continuity between terminals 12 and 5 but I have no idea where Engine ECU? CPH? Yellow connector? Black connector?

It’s a minefield.

[wheeler]

It is impossible to test with the CPH connected. Not without buying some ultra short probes or something that can be plugged into the connector because it is SO inaccessible.

This test can be done with the CPH unplugged, The wires go to earth when the door is opened or closed, just probe the terminal & open/close the door to see if the earthed or not earthed status changes.

[Rhothgar]

This test can be done with the CPH unplugged, The wires go to earth when the door is opened or closed, just probe the terminal & open/close the door to see if the earthed or not earthed status changes.

This is half my problem, Wheeler! Understanding what can and can't be tested plugged in.

Lexia came up with fault codes tonight.

Permanent fault - Locking failure caused by the right door locking button
Ditto. left door locking button.

If this refers to the actual switched which the CPH needs to see then could they have just occurred because I had had the CPH disconnected?

I cleared the faults and they didn't come back. My worry is that whatever the fault is, it is intermittent.

I took lots of screenshots off the Lexia and wonder if I should post them up. Someone might spot something untoward.

I had to laugh stripping that yellow connector down, it took me 10 minutes to carefully cut the cable tie off. In the end, I just had to cut and pray I hadn't gone through the wires. It's so tight in there.

Then I had to work out how to deconstruct it - 1 minute. I guess it's easier on a workbench...

Injected flow reference is 34mm3/stroke. That seems massive. I am pretty sure it should be 11mm3 if it's running right.

[Rhothgar]

Here is the Injection & immobiliser diagrams.
Id maybe check the communication wires between the Injection ECU & CPH.
pin 7 of yellow connector on the CPH to pin 66 of the ECU
pins 6/19 of yellow connector to pin 36 of ECU.
I would volt drop check them under load.

Just revisiting your posts, Wheeler.

I had meant to check the serial input line and output line before.

Need to firstly pick your brain on this a bit more. Not sure if you have access to the Diagnosis Manual, mine is for December 1997 on so I hope there were no changes after.

In Diagnosis Manual, I've been through it with a fine tooth comb, under Fault Code 6 (presumably this would be an Elit Fault code?) key not recognised it states there are two types of code:-

a fixed identification code
an authentication code which changes each time the ignition is switched on.

Fault code 1 deals with resupply to the engine ECU and that appears to be something to do with locking to/from? Pins 7 to 66.

Fault code 2 deals with no response from engine ECU and commands from CPH for unlocking and locking to/from? Pins 19 and 36.

Fault code 3 deals with engine ECU locking problem and commands for unlocking, locking and initialisation to/from? Pins 6 and 36.

Now as Lexia reports Unlocked when key is in ignition am I right to assume that it sends the identification code from the transponder to the CPH and then onto ECU which responds via either line 36 or 66?

But when the key is turned, Lexia reports No response from Engine ECU.

Now! I am surmising but the engine ECU has received the identification, it confirms it is OK, and sends some kind of code to the CPH between, I assume, pins 7 and 66 and the transponder tries to confirm the code and sends the authentication code back along either Pin 6 or 19 back to the ECU which then gives, "No response" either because a wire is broken or the code is not recognised for some reason.

As the wires from Pins 6 and 19 are spliced, I am thinking the one of the wires either has high resistance or is broken between splice 820 and the CPH module. One wire from one pin (say Pin 6 for argument's sake) for the identification code and one wire from the other pin for the authentication code (say Pin 19 or vice versa).

My questions are:-

a) Does the above seem a reasoned understanding of how the system works?

The manual indicates that Pin 19 deals locking / unlocking. Pin 6 for locking / unlocking / initialisation and Pin 7 for resupply to engine ECU.

As the relay seems to click once the in-tank pump has primed, I assumed that this was normal though I am not sure it is.

I think now (despite what I have said above) that the CPH is probably relocking the ECU via Pin 7 and 66 because of it not receiving the authentication code (however that is generated) and then perhaps switching (what I call) the primary side of the double relay off through Pins 1 and 29 of the relay (unless my car does have the resupply relay somewhere as described in the Diagnosis Manual) which supplies the fuel pressure regulator and the inertia switch.

b) How would you perform a voltage drop test specifically on such fine wires?

I have an H4 bulb but it would surely melt the wires. If you could be prescriptive it would be a great help. Despite my current level of understanding of diagnostics, don't be fooled. 9 months ago I would have no even entertained looking this deep into an electronics issue.

I feel so close now. I hope it will be rewarded very soon.


I hope this makes sense Wheeler (and anyone else that might like to add) and that you are able to confirm or deny the above.

[wheeler]

My questions are:-

a) Does the above seem a reasoned understanding of how the system works?

The manual indicates that Pin 19 deals locking / unlocking. Pin 6 for locking / unlocking / initialisation and Pin 7 for resupply to engine ECU.

As the relay seems to click once the in-tank pump has primed, I assumed that this was normal though I am not sure it is.

I think now (despite what I have said above) that the CPH is probably relocking the ECU via Pin 7 and 66 because of it not receiving the authentication code (however that is generated) and then perhaps switching (what I call) the primary side of the double relay off through Pins 1 and 29 of the relay (unless my car does have the resupply relay somewhere as described in the Diagnosis Manual) which supplies the fuel pressure regulator and the inertia switch.

b) How would you perform a voltage drop test specifically on such fine wires?

I have an H4 bulb but it would surely melt the wires. If you could be prescriptive it would be a great help. Despite my current level of understanding of diagnostics, don't be fooled. 9 months ago I would have no even entertained looking this deep into an electronics issue.

I feel so close now. I hope it will be rewarded very soon.


I hope this makes sense Wheeler (and anyone else that might like to add) and that you are able to confirm or deny the above.

OK What exactly goes up & down the communication wires is a bit above my head however what your saying seems perfectly feasible.

Looking at where splice E820 is located I'd say its definitely worth a check. Splices can & do rot, You can usually see the giveaway green/blue powder, Give the wiring a good tug at the splice & they sometimes just break off, if any doubt re splice it.

To check the wires have both the CPH & injection ECU disconnected. Do a resistance check between 19 & 6 then separately between each of those pins & pin 36 of the injection ECU. If all of those checks are less than 1 ohm check that there is no continuity between any of those pins & earth.
Do a resistance check between pin 7 on the CPH & pin 66 of the injection ECU, If that's ok again confirm there is no continuity to earth.
Normally I wouldn't regard a resistance check alone as a good indicator of wire condition but as this wire will carry virtually no load it should be ok.
If you did want to be thorough you could load check the wires, as the circuit does not carry any real load you would need to add your own load in the form of a bulb.
you will need to improvise some wiring/connections. The wiring should be fine as you will only be loading is for a few seconds but you don't need anything as big a an H4 bulb, A 21w will be fine.
Again both CPH & ECU disconnected
Send 12v straight from the battery down one of the wires (ECU side would be the obvious choice here), at the CPH end connect the bulb & earth it, compare the brightness of the bulb to direct connecting it to the battery, if there is any volt drop you will see a difference in brightness.

[GiveMeABreak]

I'm just going to chip in here with some additional info as if and when you are testing there are specific events that take place after a certain time lapse that you may / may not be aware of and that may throw you off-track when you are testing. Pay specific attention to the door opening and timings and the consequences:

Other stuff is for reference.

Further on down, is some detailed info on testing that you might find useful.

Transponder Operated Anti-Theft Device

Key Reference Designation 1 Permanent +. + after ignition and earth 2 Alarm LED 8 Key-in-ignition audible warning 14 Centralised diagnostic socket (16 or 30 channels) 15 Engine management computer (ECM) 16 Door open warning lamp 17 Transponder warning lamp 18 Transponder analogue module 19 Integrated transponder 21 High frequency remote control unit 25 Doors open switch assembly 8630 Body computer (CPH)

Operation

(14) Centralised diagnostic socket . (18) Transponder analogue module. (19) Integrated transponder. (26) Driver’s door switch. (27) injection ECU (petrol or diesel). (29) diesel injection pump. (28) Injection double relay (supply to the ECM). (8630) Body computer (CPH).

Detecting a key left in the ignition
When the ignition switched supply is cut off and the driver’s door is opened, the body computer performs a search to detect if the key has been left in the ignition.
If the body computer detects a key with a recognised transponder code:

• The key in ignition audible warning is activated and generates a signal
• The signal is initially fixed for 0,6 seconds, then pulsed at a frequency of 2 Hz

The audible signal stops if the key is removed from the ignition or if the driver’s door is shut.
The audible signal will continue to sound for 30 seconds after the ignition is switched off if no action is taken.

Unlocking the fuel injection ECU
When the ignition key is in the "ignition on" position:

• The red LED goes out (unless the alarm is armed), and the unlocking warning lamp on the instrument cluster comes on
• The system reads the key code
• The ECM informs the body computer of its current state (locked or unlocked)

If the ECM is in the "unlocked" state:

• The warning lamp on the instrument cluster goes out
• The vehicle can be started

If the ECM is in the "locked" state, or if no information is received about the state of the ECM:

• The body computer recognises the key code
• The body computer transmits a command to the ECM to unlock
• The ECM replies by relating its new state

Note: If the new state is "unlocked", the command to unlock having been accepted by the ECM, the warning lamp on the instrument cluster will go out.

If the key code is not recognised by the body computer (command to unlock not accepted by the ECM, or if no information is received about its state): The warning lamp on the instrument cluster flashes at a frequency of 2.5 Hz and the audible warning emits a continuous signal either until the ignition is switched off or for 30 seconds.

Locking the fuel injection ECU
The body computer automatically initiates the locking procedure:

• Either 5 minutes after the ignition is switched off
• Or 10 seconds after the driver’s door is opened (if the ignition switched + has been cut and if the door is opened within 5 minutes after the ignition is switched off)

Note: If the driver’s door is already open when the ignition is switched off, the locking procedure will be initiated 10 seconds after the ignition is switched off.

Locking procedure:

• The body computer resupplies the ECM via the injection double relay ( 1), or the anti-theft relay (2)
• The ECM informs the body computer of its current state

Note: (1) Electronically operated diesel and petrol engines. (2) Diesel engines with a mechanical pump.

If the ECM is "locked":

• The body computer cuts the supply to the ECM (resupply relay)
• The alarm LED flashes at a frequency of 2 Hz

If the ECM is "unlocked":

• The body computer transmits a command to the ECM to lock
• The ECM informs the body computer of its current state: The alarm LED flashes at a frequency of 1 Hz

If the new state is locked:

• The body computer cuts the supply to the ECM
• The frequency with which the LED flashes changes from 1 Hz to 2 Hz

If the new state is unlocked, or if no information is received about the state:

• The lock command is repeated every minute
• If the ECM is still not locked after 4 new attempts, then the body computer will cut off its supply (supply restored when the ignition is next switched on)
• The frequency with which the LED flashes changes from 1 Hz to 2 Hz

Note: If the ignition "+" is switched on again before the ECM supply is cut off, the locking procedure is interrupted and cancelled.


Anti Theft Function Checks

Part (1) Checking the Engine ECU Lock

A) By Using a Key Shield

A metallic shield inserted between the analogue module antenna and the electronic device located in the key prevents the former from reading the latter . A faulty key can be simulated in this way. This shield can be made by drilling a 8 mm hole in the centre of a suspension sphere thread protection cap (1).

Procedure:

• Switch off the ignition, Open the driver’s door and wait for 10 seconds (the key-in-ignition audible warning stops).
• Insert the ignition key into the 8mm hole drilled in the shield.
• Switch on the ignition using the screened ignition key, The transponder warning lamp in the instrument panel flashes, and the audible warning emits a pulsed sound.
• If the ECU is correctly locked, the engine cannot be started.

B) By removing the ignition on information

Procedure:

• Switch off the ignition , Open the driver’s door and wait for 10 seconds (the key-in-ignition audible warning stops)
• Remove fuse F2
• Switch on the ignition, The transponder warning lamp in the instrument panel does not come on
• Attempt to start the engine, The transponder warning lamp in the instrument panel flashes and the audible warning emits a pulsed sound
• If the ECU is correctly locked, the engine cannot be started

C) Using the transponder warning lamp in the instrument panel

Procedure:

• Switch off the ignition, Open the driver’s door and wait for 10 seconds (the key-in-ignition audible warning stops).
• Close the driver’s door.
• Switch on the ignition, Observe the time required to unlock the engine ECU (the time that the transponder warning lamp in the instrument panel is on for).
• Switch off the ignition.
• Switch on the ignition, Observe the time that the transponder warning lamp in the instrument panel is on for, Engine control unit unlocked.

The second time the ignition is switched on, as the CPH does not have to unlock the ECU, the warning lamp should come on for a shorter period of time.

Note: The time that the warning lamp is on for also depends on the type of engine ECU fitted to the vehicle, Certain ECUs respond faster than others.

Using the LED for vehicles fitted with an alarm

For vehicles fitted with an alarm, and depending on the CPH configuration (programming), the alarm LED can also be used to check the state of the engine ECU.

• Ignition off, the LED stays off then starts to flash 10 seconds after the driver’s door is opened. The LED will flash slowly (1 Hz) to indicate that the CPH has been informed that the engine ECU is locked.
• Ignition off, the LED will continue to flash until the CPH is informed that the engine ECU has been unlocked.

Caution: When ignition is switched on, the LED flashes immediately if the CPH has not been informed that the engine ECU is unlocked.

Part (2) Symptoms related to the immobiliser function

Part (3) The diagnostic equipment cannot communicate with the CPH

When carrying out a diagnostic check of the CPH with diagnostic equipment, the vehicle lock motors are not activated; The diagnostic equipment reveals a communication failure with the ECU

Possible fault causes	Method of checking
Faulty connection with the diagnostic socket	Connect the electrical test unit to the CPH Check the continuity and isolation of the connection between terminal 6 of the diagnostic socket and terminal 11 of the 26-way yellow connector of the CPH Also check that the diagnostic equipment is working correctly
Faulty body computer	Connect the electrical test unit to the CPH Check the plus permanent electrical supply between terminals 4 and 13 and terminals 1 and 13 of the 15-way black connector of the CPH If not, Check fuses F15 and F25

Part (4) The engine ECU is not locked (vehicle not protected)

The door-open warning lamp does not come on if only the driver’s door is open

Possible fault causes	Method of checking
There is dialogue between the diagnostic equipment and CPH	The CPH will not operate during dialogue with the diagnostic instrument Check that the CPH diagnostic check has been fully terminated if locking has not taken place
No driver’s door open information	Check the connection to the driver’s door lock If there is no driver’s door information, the engine ECU will only be locked 5 minutes after the ignition is switched off

Opening the driver’s door will cause the door-open warning lamp to come on

Possible fault causes	Method of checking
The engine ECU has not been initialised	Select the engine ECU initialisation during the CPH diagnostic check The vehicle access code, recorded on the customer’s confidential card, must be available After terminating the diagnostic operation, check that the warning lamp works correctly and ensure that the CPH locks the engine ECU properly (see Part (1)).
The CPH has not been initialised	The transponder warning lamp in the instrument panel does not come on when the ignition is switched on. Using the diagnostic equipment to read the parameters, Check that the CPH has been properly initialised (number of keys initialised is not zero). Otherwise initialise the CPH. It is necessary to have available both the vehicle access code, recorded on the customer’s confidential card, as well as all the vehicle keys. After terminating the diagnostic operation, check that the warning lamp works correctly and ensure that the CPH locks the engine ECU properly (see Part (1)).
No electrical resupply to the engine ECU after switching off the ignition	Connect the electrical test unit to the CPH Ignition off, driver’s door closed. There should be 0 volts at terminal 7 of the 26-way yellow connector of the CPH. Driver’s door open. The CPH should resupply the ECU 10 seconds after the ignition is switched off. For approximately one second there should be U ð 12 volts. Check the continuity and isolation in relation to the earth of both the resupply line and resupply relay (if fitted). If the CPH is faulty and the vehicle is fitted with a resupply relay, replace both of them.
There is no dialogue between the CPH and the engine ECU	Check the continuity and isolation in relation to the earth between terminal 6 of the 26-way yellow connector of the CPH and the engine ECU. Using a voltmeter, check that a change occurs at terminal 6 during the locking phase.

(*): If the initialisation procedure has been interrupted, the number of keys memorised may not be zero even though the CPH is not initialised.

Part (5) The engine will not start

When ignition is switched on, the transponder warning lamp in the instrument panel flashes, and the audible warning emits a pulsed sound

Possible fault causes	Method of checking
Key faulty or not recognised	Switch on the ignition using the other keys. If none of the keys will start the engine, there could be a problem with the antenna or the CPH. Check that the antenna connector is properly connected. If this is the case, Connect the electrical test unit to the CPH. Check the transponder analogue module. If another key starts the engine, the key is faulty or hasn’t been initialised. Initialise the keys. It is necessary to have available both the vehicle access code, recorded on the customer’s confidential card, as well as all the vehicle keys. The initialisation procedure is interrupted once a faulty key is detected. Initialise the keys again without the faulty key.
No supply to the engine ECU	Connect the electrical test unit to the injection ECU and check that it is receiving a supply. Check the fuses and the double relay. In the case of diesel pump modules, use the ADC test cable to check the supply.

When ignition is switched on, the transponder warning lamp in the instrument panel does not come on. When trying to start the engine, the transponder warning lamp in the instrument panel flashes and the audible warning emits a pulsed sound

Possible fault causes	Method of checking
No ignition switched "+" information	Using the diagnostic equipment to read the parameters, check that the CPH is correctly receiving the ignition switched "+" information. If not, Check the fuse F2. If the fuse is in good condition, connect the electrical test unit to the CPH. The ignition switched "+" must be present at terminal 5 of the 15-way black connector.

When ignition is switched on, the transponder warning lamp in the instrument panel does not come on. The vehicle cannot be locked using the plip.

Possible fault causes	Method of checking
There is dialogue between the diagnostic equipment and CPH	The CPH will not operate during dialogue with the diagnostic instrument. Check that the CPH diagnosis has correctly terminated if the engine will not start.
The CPH has not been initialised	The transponder warning lamp in the instrument panel does not come on when the ignition is switched on. Using the diagnostic equipment to read the parameters, check that the CPH has been properly initialised (number of keys initialised is not zero). Otherwise initialise the CPH. It is necessary to have available both the vehicle access code, recorded on the customer’s confidential card, as well as all the vehicle keys. After terminating the diagnostic operation, check that the warning lamp works correctly and ensure that the CPH locks the engine ECU properly (see Part (1).
Faulty body computer	Connect the electrical test unit to the CPH. Check the plus permanent electrical supply between terminals 4 and 13 and terminals 1 and 13 of the 15-way black connector of the CPH. If not, check fuses F15 and F25.

(*): If the initialisation procedure has been interrupted, the number of keys memorised may not be zero even though the CPH is not initialised.

Part (6) The engine does not stop When ignition is switched on

Possible fault causes	Method of checking
The re-supply relay is faulty (if fitted).	Check that the relay switch is not stuck.
The CPH permanently controls the resupply of the engine relay	Connect the electrical test unit to the CPH. Ignition off, driver’s door closed. There should be 0 volts at terminal 7 of the 26-way yellow connector of the CPH. Check the isolation in relation to the resupply line + 12 volts. If the CPH is faulty and the vehicle is fitted with a resupply relay, replace both of them.

Part (7) The transponder warning lamp in the instrument panel does not come on when the ignition is switched on

Possible fault causes	Method of checking
The warning lamp is faulty	Ignition on, with the diagnostic equipment testing the actuators, check that the warning lamp comes on (for 0.5 second). If not, Check the fuse F12. If the fuse is in good condition, connect the electrical test unit to the CPH. Check the continuity and isolation of the warning lamp control line.

The vehicle cannot be locked using the plip

Possible fault causes	Method of checking
There is dialogue between the diagnostic equipment and CPH	The CPH will not operate during dialogue with the diagnostic instrument. Check that the CPH diagnosis has correctly terminated if the engine will not start.
The CPH has not been initialised	The transponder warning lamp in the instrument panel does not come on when the ignition is switched on. Using the diagnostic equipment to read the parameters , Check that the CPH has been properly initialised (number of keys initialised is not zero). Otherwise initialise the CPH. It is necessary to have available both the vehicle access code, recorded on the customer’s confidential card, as well as all the vehicle keys. After terminating the diagnostic operation, check that the warning lamp works correctly and ensure that the CPH locks the engine ECU properly (see Part 1).
Faulty body computer	Connect the electrical test unit to the CPH. Check the plus permanent electrical supply between terminals 4 and 13 and terminals 1 and 13 of the 15-way black connector of the CPH. If not, check fuses F15 and F25.

(*): If the initialisation procedure has been interrupted, the number of keys memorised may not be zero even though the CPH is not initialised.

When ignition is switched on, the transponder warning lamp in the instrument panel does not come on. When trying to start the engine, the transponder warning lamp in the instrument panel flashes and the audible warning emits a pulsed sound

Possible fault causes	Method of checking
No ignition switched "+" information	Using the diagnostic equipment to read the parameters, check that the CPH is correctly receiving the ignition switched "+" information. If not, check the fuse F2. If the fuse is in good condition, connect the electrical test unit to the CPH. The ignition switched "+" must be present at terminal 5 of the 15-way black connector.

Part (8) The key-in-ignition audible warning does not work

When ignition is switched on, the transponder warning lamp in the instrument panel does not come on. The vehicle cannot be locked using the plip. See Part (7).

The door-open warning lamp does not come on if only the driver’s door is open

Possible fault causes	Method of checking
No driver’s door open information	Check the connection to the driver’s door lock. If there is no driver’s door information, the engine ECU will only be locked 5 minutes after the ignition is switched off.

The door-open warning lamp comes on when only the driver’s door is open

Possible fault causes	Method of checking
Faulty audible warning	With the diagnostic equipment testing the actuators, check the operation of the audible warning (for 0.5 second). Check that the audible warning is receiving the correct supply. Check the continuity and isolation of the audible warning control line.
Faulty body computer	Connect the electrical test unit to the CPH. Check that it controls the audible warning when the ignition is switched off with a door open. It must read: Ignition on: U ≈ 12 V. When ignition is switched on: U ≈ 0 V.

[Rhothgar]

OH NO!

I typed a really long response thanking Marc and Wheeler and then went back to post by RichardW and clicked quote button and it wiped the reply. This is not going to be a good day.

I'm not typing current observations and stuff all over again as I need to get down to the car and conduct so further tests so thanks ever so much Marc and Wheeler for your last two posts but I'll keep this reply less verbose.
GUTTED!

@Marc. Some great information there. Pretty much ruled out transponder on Wednesday but there are a few things in your post that are very pertinent so will hopefully check those today. Chat with CitroJim, also on Wednesday is pointing me to problem with HP pump even though the car starts and dies. Also, long chat with CitroenCrazy late Wednesday night. He sent me an Info'Rapid link concerning IC60 which takes signal from fuel pressure sensor. It can get damaged during clutch changes. I have fiddled with it and I do see 1.2V on scope trace when engine starts so fuel pressure sensor is fine. Will still double check wiring.

@Wheeler. Some very useful testing information there. I think I may have tested the fuel pressure regulator wiring a couple of weeks ago with an H4 bulb and ECU connected. CC has a spare ECU on standby for lending me to finally rule that out. Ideally, could do with a diesel line pressure tester to rule out HP pump but will try easy start and see if readings change on Lexia to rule pump out maybe. Will also check E820. Been meaning to do that but signals do seem to be transferring between ECU and transponder according to the oscilloscope readings I took on Tuesday.

@RichardW. The wiring under the radiator contains a splice which carries the signal from the engine speed sensor from memory. If the ECU is not receiving engine speed data (presumably this is the rev counter), then will that stop the car from running? I can see cranking rpm in Lexia so presumably that means it's OK. I cannot see anything else in that loom that would affect engine running.

[Rhothgar]

Well that did turn out to be a disastrous late morning and afternoon.

Check IC60 and that is all fine. Not load tested it as yet but will do. No variation in the reading on the Lexia when the wires were agitated as per the Info'Rapid tech doc.

Next I moved to trying to start the engine on carb and throttle cleaner as a volatile compound instead of easy start. Can't see any reason why this would not work in place of easy start?

Anyway, no joy. Problem there is as I have to switch the ignition off because the relay is cutting out when the ignition is on, Lexia then goes back and you need to press the Return button 3 times to validate it and get back into Parameters 1 screen which if the car doesn't start cannot show if the fuel rail pressure has increased. It was worth a try.

So then I turn my attention to splice E820. That looks 100% fine.

I disconnect ME15A earth next to IC02. IC02 internals all look fine.

I drop the bolt into the the gap by the headlight. Forget how to get the indicator out and start to pry it from the side. Indicator lenses came away. Managed to get indicator out. Tried to superglue lenses back on. That didn't work so hit it (more in anger than trying to get glue to work) broke said indicator lenses. Found bolt and put that all back together.

The transponder and alarm system is working exactly as per Marc's post although I couldn't get the LED to go at 2Hz under any circumstances only 1Hz. Not sure if that is a clue to anything.

I admit that I also thought hang the expense I'll buy the in-tank pump from ECP. Despite being well packaged a part had broken off somewhere along the line. So that needs to go back. I tried it. It make a slight difference to cranking pressure. I saw 63 bar max instead of 47 bar.

One other thing I did notice was when I put the pump in, I couldn't get the plastic 'nut' to engage right because there is half a tank of fuel in and it was trying to float the pump whilst I was trying to screw it in.

I think I cross threaded it and it was not sealed properly.

Is the green O-ring there to prevent diesel spillage from the tank or to create an air-tight seal? I am guessing but this is irrelevant because the in-tank pump sits in the fuel and pumps it up into the feed so this should not affect booster pump pressure even if the booster pump was not to be locked into place fully.

Managed to get the old pump in again and the 'nut' straight.

This is turning into a right nightmare.

I would rather test the pressure with a gauge before even swapping the HD Pump out as then if I can prove it has gone I could decide to buy a brand new pump and do cambelt at same time. As it is, I am looking for a 2nd hand pump and won't be changing the cambelt unless I can get the engine started ever again.

[Rhothgar]

Photos of today’s fun and games!

[Rhothgar]

Part (6) The engine does not stop When ignition is switched on

Possible fault causes	Method of checking
The re-supply relay is faulty (if fitted).	Check that the relay switch is not stuck.
The CPH permanently controls the resupply of the engine relay	Connect the electrical test unit to the CPH. Ignition off, driver’s door closed. There should be 0 volts at terminal 7 of the 26-way yellow connector of the CPH. Check the isolation in relation to the resupply line + 12 volts. If the CPH is faulty and the vehicle is fitted with a resupply relay, replace both of them.

Hi Marc.

Can't believe the car won't start again! Been sitting for 5 weeks. Turning over very quickly. Will connect Lexia and see if there is anything obvious.

But the above information you kindly posted relating to immobiliser function, you will see Part 6 says engine does not stop when the ignition is switch on.

Should that be "does not start" or "when the ignition is switch off."?

And the re-supply relay? Do you know if my car has this or is it simply referring to the double relay?

Thanks in advance. Would love to get the car running reliably before any cold snap as I quite like the idea of the pre-heater in the X2 and getting warmer sooner on short journeys rather than suffering in the X1 this winter. Should have done these jobs in summer.

[white exec]

I have recently had a protracted issue on the XM, caused by some very suspect work by Citroen here, which involved removal (unplugging) of the engine/injection ECU. Citroen caution that BOTH battery terminals should be disconnected before the ECU is unplugged/reconnected.

This was very likely not done (battery left completely connected), with the result that one of the diodes in the double (injection) relay became burned out. This caused problems with starting and the keypad immobiliser. (Connecting the 55-way plug with power still applied probably results in an out-of-sequence power-up of the ECU and relay.)

Lexia threw up a fault with "resupply relay", and it wasn't immediately obvious what or where this was. Turned out to be the double (injection) relay, often referred to as the Bitron relay (although this is only a manufacturer's name, now owned by the Omron corporation).

The relay contains two separate and not inter-connected relays, and four diodes. Two of these diodes are simply reverse-coonnected across the relay coils, but the other two are essential to the correct sequential operation of the system.

Replacement of the relay (make sure you get the correct type) immediately cured the problem.