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

[Rhothgar]

Hi guys,

Still ongoing but feel like it is piecing together gradually.

I noticed on Lexia yesterday than in the Parameters screen for Anti-Theft that it reports, "Engine ECU response - Unlocked", When I turn the key, it stays unlocked for about 1 second and then reports "No response".

This ties in with voltage dropping out at the double relay after the in-tank pump shuts off.

If ignition is turned up, the in-tank pump primes for around 6 seconds and then stops. Car will not start.

If ignition is switched straight to crank, the car fires and dies within 1 second. I guess the priming function automatically cuts when the engine starts but it should keep running shouldn't it?

I need to figure out why after the key is switched up, it loses connection between CPH and ECU. Any ideas would be appreciated?

I have Diagnosis RPO 7668 on dated December 1997 but not sure if one was issued for my later RPO.

From memory, VIN is

VF7**************[VIN obfuscated, can be read by forum staff]

or

VF7**************[VIN obfuscated, can be read by forum staff]

Also, CPH is supposed to be behind glovebox with two connectors, one yellow, one black. Can't see it anywhere. I can see a module of some kind near to the centre console but it has a white connector.

Factory manual shows it somewhere above the passenger airbag. I have not idea how that comes out...

[RichardW]

For testing why not jump a 12V supply onto the pump and then see if it will run?

The CPH is above the glove box somewhere, I think you have to remove the glove box to get it out, even then it is awkward, and not easy to see - I can't remember the exact details, but I extracted the CPH from mine before I scrapped it, and I remember it wasn't easy!

I wonder if the fault might be failure of the wiring harness under the radiator....

[wheeler]

You do need to remove the glovebox to get at the CPH.
I'll have a look at a diagram shortly
Is it a saloon or estate?
110 bhp model?
Manual gearbox?

[Rhothgar]

Guys. Sorry should have made myself clearer.

Have tried 12V direct. It does. It run. Lexia reporting no response from ECU 1 second after turning key.

Glovebox was removed yesterday. I am now trying to remove airbag. According to a Xsara manual it’s two nuts! There’s lots of nuts connecting the Xantia one.

I can disengage padding to airbag. Bottom two at least then no more. Airbag unit needs to come out for easy access.

Car is 110 HDI Saloon with manual gearbox, Wheeler. Cheers.

[wheeler]

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.

Both these wires go from the CPH to the engine ECU via the IC01 bulkhead connector & IC02 RH inner wing connector.

[Rhothgar]

I managed to remove it. Pointless exercise really as you cannot backprobe ANY of the wires on the yellow connector.

It’s a complete nightmare to manoeuvre out of its space above the blower ductwork.

I saw four pieces of mouse poo. I am praying that the wires are intact as it would be a fascia out job to look for signs of eaten wiring! And I really don’t want to go there!

[Rhothgar]

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.

Cheers Wheeler. I do have the full manuals but only in hard copy format. I would love downloadable copy so I can laminate them.

Is there another way to check the continuity and isolation just from ECU side because it is impossible to backprobe yellow connector. Citroen would have had a break-out box with the correct connectors to break-out the harness!

Wires come in top left of photos parallel with connected base!!!!

[wheeler]

You can disassemble the connector.
Slide off the little black bit on the left side (as it is in the pic), Snip off the cable tie where the wires go in, then you can slide out the inner part of the connector after opening the locking tabs. This should expose the pins.
Yes, a breakout box makes things much easier.

[Rhothgar]

I wish I had more than one key for the car.

The Diagnosis Factory Manual States has two tables for testing. Table 1 if the vehicle cannot be started with ANY of the keys and Table 2 if it cannot be started with one but can with others.

Just wondering if the key needs re-initialising BUT have never done it and don’t want to try it with the only key I have...

Both tables refer to driver’s door being open. I’ve noticed that the B pillar light doesn’t come on when I open the driver’s door.

I get the 10 second audible beep so perhaps switch is OK. That means the CPH has recognised the key identification code.

It passes Table 1 Check 2.

Check 3 is the continuity and isolation of which you speak.

[Rhothgar]

You can disassemble the connector

Do I really need to go here at this stage?

[wheeler]

You can disassemble the connector

Do I really need to go here at this stage?

It takes about 15 seconds to disassemble the connector.

You have nothing to loose as the car is not starting, if you have the security code Lexia will guide you through it, its very easy

[Rhothgar]

I still don’t think I will be able to get DMM probes in to test.

Also PLEASE bare in mind that Lexia is NOT registering any fault codes per se. Only the “No response from Engine ECU” once the key is switched on!

Engine ECU is unlocked once key is inserted into engine and not turned. Doesn’t this suggest transposer is fine until key is turned or am I missing something fundamental?

[wheeler]

I get the 10 second audible beep so perhaps switch is OK. That means the CPH has recognised the key identification code.

What im not sure of is if the audible beep happens if any key signal is detected or only if the correct key is detected.
Use live data & confirm that both door switches are operating correctly as they do have an effect on the CPH locking.
Believe it or not but a faulty door latch can prevent the car starting.

[wheeler]

I still don’t think I will be able to get DMM probes in to test.

You will get DMM probles in no problem. This is the same type of connector but smaller, here it is disassembled & you can see the contacts. It literally taken me 10 seconds to get it apart.
You can even remove the individual terminals if you want.

[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.