Hi all,

Whilst doing some research on ECUs I have come to the conclusion that the wrong one is fitted to my R reg 2.5TD. service.citroen.com suggests it should be the 0 281 001 589 but it is a 0 281 001 336 which is fitted. There's no way of knowing if they are interchangeable but certainly when I try a 0 281 001 212 in the car it does not like it. The stop solenoid vibrates on and off very quickly when the ignition switch is turned on.

Anyway, during that research I discovered the various permutations of ECU which are fitted to the 2.5TD (including advice from John, Robert and others) and have compiled them into the attached document. It is a work in progress so if anyone can shed any light on any other permutations, be my guest. I will upload the file as a pdf with a Revision number. If it changes with new information over time I can either post the word copy so that it can be updated or let me know what needs to change and I'll do it. If anyone has any direct ECU experience please feel free to add information. Ideally, by the time its finished it should be a pretty comprehensive document. Of course if anyone feels the need to emulate it for models other than the 2.5TD please feel free to utilise the format or any other part of the document.

When I access the ecu with both the Lexia and the Elit they both give me the same message, "The ECU has a permanent Fault". I have no idea what that means in the sense that the engine still starts and runs. However, it does not have nearly the same performance as my other 2.5s. The engine management light flashes periodically but no codes are stored.

In the next few weeks I will be borrowing a 0 281 001 589 from a friend to try for a short time so I may have something to report back after that.

Any and all help appreciated.

cheers

noz

Hi Noz

Found a bit more on the DK5 engine and done a few practical tests.

Identified two more versions of the ECU for PUG 605 cars.
Got the wiring diagrams which I need to compare with the Citroen ones.
These variants were: with keypad and no keypad fitted.
I do not think this is any more than a theoretical exercise as I have never seen or heard of a UK 2.5TD Pug 605 so chances of obtaining these ECU's is nil.

The blurb explains how the ECU works with faults.
A major fault lights the warning lamp.
Major Faults are:
Electric stop function;
Engine Speed Sensor function;
Slide Position function;
Delivery Regulation function;
Injection Control function;
Needle Lift Sensor function.
Check of associated variables:
When the control unit detects a fault it memorises 2 parameters and decreases a counter. This is to aid fault finding.
Associated variables:
For all faults - engine speed (rpm) & fault appearance counter.
Depending on fault:
coolant temperature (degrees);
diesel temperature (degrees);
actual delivery (in millegrammes per impulse)
manifold pressure (millibars).
The value of the counter depends on the number of ECU restarts without the fault reappearing. eg counter 40 = new fault. counter 38 = 2 restarts without fault re-appearing. Counter reset to 0 = fault erased.
System also has some ability to differentiate between intermittant and permanent faults.
Engine lacks power - Check:
inlet air thermistor function;
coolant thermistor function;
vehicle speed sensor function;
inlet manifold pressure sensor function;
electric stop function;
engine speed sensor function;
advance solenoid valve function;
checks & adjustments correction 2 (full load delivery);
accelerator pedal sensor function.

As for the practical tests I found a few ECU's from the junk heap and tried them:
I tried them all in early and late cars.
Have not covered all the permutations but managed quite a few.
Cars/Original ECU/State
6610/9615766180(Version 1) /Immobiliser hardware bypassed.
7161/9619559680(Version 3)/ECU code free, software bypassed in ECU.
Spare ECU's tried: 9615766180(2No. Version 1), 9623748680(Version 2 - 6819 code known),9628607180(Version 4 - code not known).
The first 3 spare ECU's listed all worked fully in 6610 car.
The last spare ECU (Version 4) gave a dead car with not signs of life.
I then took all the spare ECU's to the later 7161 car.
Results were much more mixed.
This is a version 3 car and after checking with its own ECU (started first turn of key)
I tried the later 9628207180 (version 4) ECU. Started first turn of key ran normally, no code required so that ECU is code free.
With the other 3 ECU's (version 1 &2) the results were all the same.
On switch on there was a continuous clicking from the Glowplug relay.
The engine turned over but was rough and I did not let it catch.
The reason that I did not persist was there have been reports that with this combination the engine though difficult to start once going runs away.
Not a good idea inside without good ventilation.

John

Hi Noz

I have been looking for a spare 2.5 late type ECU for a couple of months now.
Not found a source so far. I think you have similar problems.
It would seem to indicate that like strut heads this is going to become a critical item.
As an alternative I have decided to collect a couple of spare sets of bits to be able to convert a late type engine to early type. Plenty of these early 2.5's going through the scrap system at present.
My list of bits is:
ECU
Engine wiring loom
Glowplug relay (plus extra spares as these are unique to this version of engine)
Air flow pipework
Bulkhead sensor

Will need to turn this into a definitive list.

Any thoughts

Regards

John

Hi John,
.......Air flow pipework
.......Bulkhead sensor
I see these two items are on one of your mails as "wanted"
can you be more precise ,please?
I have the twin pipe plus water pump belt cover, I have also a sensor which may match your description as it is attached to the bulkhead.
Can these be of any use to you?
I did not have them with me at the CX/XM but could bring them to Stratford.
Brian

Hi Brian

Thanks for the offer but I will not be going to Stratford.
Sensors of either type are worth me collecting so if you can keep it please.

Best regards

John Manning

Hi Noz

Now got as far as opening up a spare L17 ECU.
There are two EPROM's inside, markings are:
2 287 358 818 - 0 281 001 212;
2 287 358 819 - 0 281 001 212.
There is 1 likely and 2 possible chips for the serial CMOS memory.
The 2 possibles are identical but I suspect that they are the clock/oscillators for the 2 adjacent microprocessors.

John

i have a peugeot principal of operation book on the VP 36 pump, it says there are three chips one plus two backups, to run the engine ,if i can get my landlord to let me back into my workshop i will scan it and post it ,