Wiring Diagram Citroen Xsara Forte

[Joemoonlit]

Hi,
I have been working on my Citroen Xsara Forte N1 1.4i Petrol year 2000 for over 6 months solving various issues, however, i have failed to get it through the emissions test. I suspected there was an issue with the ECU as now the cooling fan comes on permanently after starting the car.
I have done various checks with my multimeter and seem to have found that there is no permanent 12V supply to the ECU. I have tested the K line from pin 7 and it has 10.15V and continuity is positive when i tested it beteween pin 7 on the OBD2 diagnostic port and pin 30 on the ECU connector.
The lack of a permanent 12V supply may explain why the OBD2 port does not allow a scanner to link to the car. I even popped into a garage to make sure it wasn't my scanner, but even they could not link.
I have done a continuity test between the battery and the pin 49 on the ECU connector, which supposedly carries the permanet 12V supply to the ECU, and this gave a negative result so no continuity. I tried other pinds just in case but no continuity.
In order to proceed troubleshooting i need wiring diagrams (specifically for the Sagem SL96 ECU fuel injector system diagram to my specific model. I also need information on the Master fuses for my model.
I believe the following information will help:
VIN number:VF7**************[VIN obfuscated, can be read by forum staff]
Engine type code: TU3JP+ (1.4L Petrol)
Date of first registration:22.09.2000
ECU type: Sagem SL96

I haven't found the RPO number yet.

Is anyone able to share the correct wiring bdiagram for my car and provide information on the Master fuses.

Many thanks
Joe

[wheeler]

Your RP number is 8628.
Is your ECU a single 55 way connector?
If so this should be the diagram.
A quick glance over it & i can't see a permanent live on this ECU, I would expect that if it was meant to have one & it was missing then the engine wouldn't even start.
If i remember right these ECU's used to get spiked by the ignition coil packs with the black connector, something at the back of my mind is telling me that it was an emissions & idle problems it caused when it failed. If you fit a new ECU without replacing the coil pack it can damage the new ECU.

[wheeler]

Just found this > https://www.205gtidrivers.com/forums/to ... placement/

[Joemoonlit]

Hi,
Thanks so much for the information above but do you have a key for the attached wiring diagram, as I can't really decipher what is what. This would be really helpful.
Yes it is a single 55 way connector.
Would you be able to let me know which is the ECU on the diagram? I assume the big square 1320 in the centre of the diagram maybe.
Which pin do you see the permanent 12V going to on the ECU connector? Which module is the battery?
I identified the K line goes to pin 30 on the ECU connector by testing continuity from pin 7 on the diagnostic OBD2 connector in the car to the ECU connector. Pin 30 on the ECU connector gave a positive continuity test. Is this in line with the attached file?

Sorry can you maybe expand on the bit where you say "used to get spiked by the ignition coil packs with the black connector". Are you saying that the ignition coil ( the black unit that sits on top of the 4 spark plugs and is attached to the spark plugs by 4 rubbery connectors) somehow corrupts the ECU and causes issues with emissions? What do you mean by spiked? If this was the case are you saying that the ECU and ignition could would need to be changed?

The car runs really well except for the constant running fans and of course the poor emissions. Are you saying that if there was no permanent 12V supply to the ECU the car would not actually start?

Would you have any information on the Master Fuses in the engine fuse box? The owners manual shows all the fuses, except for the MF fuses!

My next step was to try and attach a separate 12V supply with fused connection (5-10A) directly to the correct pin on the ECU connector and then see if I can link my diagnostic scanner to the car at least. If this is the issue and the ECU is ok then this would allow me to start some diagnosis at least and also track the reason for loss of 12V supply. It will be somewhere between the fuse box and ECU connector as all MF fuses were receiving a 12V supply when I tested with the multimeter.

Any other ides would be great to hear. Thanks again for taking the time to reply to this post. Your input is greatly appreciated.

Kindest regards

Joe

[Joemoonlit]

Thanks for the link btw. I checked it out and one thing to note is that when I purchased the car the previous owner had said he changed the ignition coil. So I wonder if indeed some damage had been done to the ECU already as it came with emissions issues from the very start.

[xantia_v6]

Thanks so much for the information above but do you have a key for the attached wiring diagram, as I can't really decipher what is what. This would be really helpful.

The key for most electrical components on official PSA diagrams can be found at: viewtopic.php?t=80489

[wheeler]

Are you saying that if there was no permanent 12V supply to the ECU the car would not actually start?

Only if its meant to have one, however on this diagram i cant see a permanent 12v supply to the engine ECU (1320)

According to this diagram pin 7 of the OBD connector (C0001) is connected to pin 31 of the ECU. Always confirm that the wire numbers you are checking match with the diagram.

The issue with the coil damaging the ECU now i have read back up on it to jog my memory normally gives idling problems & gives the impression of a faulty idle stepper motor.

[wheeler]

As far as the emissions goes what reading(s) is it actually failing on?
What is the oxygen sensor readings doing at idle with the engine warm if you look at live data? According to the diagram this car only has one oxygen sensor, is this correct?
Have you tried driving the car very hard just before the emissions test?

[Joemoonlit]

Hi,
Thanks for the key that will be really useful.

Strange it shows pin 7 going to pin 31. I am sure when i tested continuity it went to pin 30, but will check again.

So maybe there is not supposed to be a permanent 12V supply to the ECU if it doesn't show one in the wiring diagram.
That would make sense with the tests i have done to date.

So it could be a faulty ECU that is causing the issue. That might explain why the OBD2 port does not allow the scanner to link to the car.

However, i am surprised how well the car drives and idles. It sounds really good. When i took it to the garage he said after the first fail to add some particular additive that is good and drive the car hard before bringing it back in.
I did this and during the driving i took it all over, hills, everywhere and yet it still failed. Would a car be able to run this well if the ECU was faulty?
I attached a picture (emission 1) of the emissions readout i saw on his computer. He did rev it quite a bit whilst in the garage as well. Alas to no avail.
Not sure what your thoughts are on the attached file. I will attach another file (emission 2) taken during the same visit. Not sure why the difference. Either way both failed. I think the second image was after revving it quite a bit.

[wheeler]

Is it using more fuel than normal?
I wonder if you have a fault with the coolant temp sensor? the ECU may be thinking the engine is way colder than it is & the faulty (and cause massive overfueling) temp sensor could also explain the cooling fan issue

[Joemoonlit]

I checked the temp sensor with a multimeter and it appears to work. When i took it into the garage to see if their scanner could connect they also noticed the fan and pulled the temp sensor off. He reckoned the fan should stop if he disconnected the sensor but it kept on going.
I wouldn't say that it was using more fuel than normal and if anything the spark plugs looked by their colour to be running slightly lean.
Just to add there is a brand new cat converter on the car andthere is only one pre-cat O2 sensor.

[wheeler]

When i took it into the garage to see if their scanner could connect they also noticed the fan and pulled the temp sensor off. He reckoned the fan should stop if he disconnected the sensor but it kept on going.

They actually normally operate the opposite to that, If you disconnect the temp sensor the fans normally come on at full speed, its a kind of backup strategy if the ECU doesn't know the engine temperature.

[Joemoonlit]

Ok so that is good to know. I will maybe order a new sensor and see if that works. However, it wouldn't explain why the OBD2 port isn't allowing the scanner to link to the car would it? If it isn't the 12V permanent supply to the ECU at fault (ie based on the fact that there isn't one according to the wiring diagram) then the only explanation i can think is that the ECU is faulty, but then why does the car run ok apart from the fan and emissions?

[Joemoonlit]

I read that the SL96 ECU gets its power via a double relay, and the 0004 power supply likely feeds into that relay setup.
It’s essential for powering:
ECU main circuitry
Fuel pump
Injectors
Idle control valve
Possibly sensors like MAP or coolant temp

On the wiring diagram i can see that there is a label 0004, which is not on the key. Would you know if this is the double relay. It shows a wire going from pin 13 on 0004 to the pin 9 on the ECU. I understand this relay is contained in a plastic box near to the ECU/battery. If this relay had a fault maybe it could be the reason no power is getting to the ECU. Any thoughts?

[wheeler]

0004 is the instrument panel
The main (or ‘double’) relay is 1304
Again, the failure of the double relay would normally result in a non start situation.