My Citroen XM 3.0 PR-Vestige

[Dean]

Well I went out for a 20 ish mile run, then came home for breakfast, got about 2 miles and she quit, I did get it to run again and turned it round to face the road ready for recovery and just as I got it line up she cut out again.

It is properly dead now though as when I got home I tried to start it to drive it back into the citrohutch but it was no go.

I think the ECU is confused, the heater relay is powered by the main injection relay alright, switched by the ECU but is grounded through the ignition module, I no longer have a ground at the O2 heater relay so suspect the Module. I will search the web for the specs to see what pin is the switched ground signal to the coil and make sure it is the module but as Will says the way it fails when hot would suggest a solid state electrical component.

The coil polarity is correct Will.

£40+V.A.T to be taken home so no great problem, £48 I would like to of kept hold of but then if I take these chances, it was kind of expected.

D

[MTXM]

I was sorry to hear that you suffered the breakdown Dean and these things are sent to try us! At least you seem to have pinpointed the problem and how very unlucky that the module suddenly and unexpectedly failed. I have not had a module pop myself and is this a common issue? As a consequence of general reliability there are several spares knocking around my garage if you are desperate, although I know availability new is good, which you may understandably prefer! Regards, Matthew T.

[Dean]

They are actually very reliable Matthew, not that prone to failure at all. i'm going to have a good check over after story time, it would seem after a quick check the fault is still there as there is no coil voltage but i also seem to have a fuel leak too which has just this minute appeared out of nowhere. We shall see what we can see.

D

[Dieselman]

No coil voltage must be the feed side of the coil, not the IGN module side. The IGN module shorts the coil to GND to create the spark.

[Dean]

Here is the roadside diag screen, ignore the relay, that's because i was had unplugged it to substitute with a new one.
IMG_3339 by Deanxm, on Flickr

There are only 3 wires that run to the ignition module and coil loom, one yellow ground, one blue + and a green signal wire from the ecu. These turn into 4 wires connected to the module with a 5th jumper wire that connects terminal 5 and 6. with two wires to the coil itself, so far as i can understand there is no need for power to be going anywhere near the module but it does.
I cleaned the relay terminals up and crimped the sockets, also tested the relays and it all checks out.

I found bending the loom over that goes into the ICM gave 12v at the coil, so i tied the bunch of wires over and the car started and ran perfectly for about 30 seconds and then just turned off again, I still had 12v at the coil and it would not restart. The plug pins out fine but im wondering if its flexing the pins in the ICM itself and making contact, or i have two problems so im going to cut the whole loom off and replace it with a much better quality MK2 section.

Pulled the ICM off and had a look, the heatsink was dry as something very dry indeed and burnt (right), the one from the Prestige (left) has had the heat sink paste wiped off, i used to replace it every few years.
IMG_3341 by Deanxm, on Flickr

Also found my permanent speed sensor fault is the road speed, not engine speed so that's nice to know and will look at reinstating a road speed signal to the ECU.

D

[Dean]

I was sorry to hear that you suffered the breakdown Dean and these things are sent to try us! At least you seem to have pinpointed the problem and how very unlucky that the module suddenly and unexpectedly failed. I have not had a module pop myself and is this a common issue? As a consequence of general reliability there are several spares knocking around my garage if you are desperate, although I know availability new is good, which you may understandably prefer! Regards, Matthew T.

Matthew, while a brand new Bosch or Valeo branded unit would be lovely they are £60 and the better half and i have come to an understanding that "we" will not be spending any more on the car, in order to help defuse any future 'situations' i think it would be wise to save every penny i can, especially when you consider she knows nothing about being towed home today, and while i think the cost was very reasonable, i doubt very much if she will! I will PM you tomorrow.

D

[misha]

You can buy a used ignition module for double less.Maybe some member or your friend have some spare ones,just to try.

[Dean]

Well, this evening I replaced that whole section of the loom, I'm lucky in that the main loom is really good, clean and the wire insulation still basically as I would expect to find new, i guess running over the top of the engine it's kept nice and clean.

I took the alloy heat sink off, glued some fine sandpaper to my steel top workbench and sanded it to get a good clean surface, i did the same with the burnt heat sink plate on the back of the ignition module and quickly noticed it was bent like a banana, I had to switch to some 120 grit and really go at it taking nearly 1mm off before it was flat then applied a smear of heat sink paste and fitted it and the alloy plate to the car.

I now have a solid 12.5 volts at the coil instead of a maximum of 11.8 and wiggling the multi plug on the ICM doesn't provoke a faltering or non-existent voltage so im happy i have solved at least one problem, i started the car and it fired straight up and ran really nicely, the idle is super stable like it never was before but after a minute of two the engine just turned off.

It runs really well, like new! but still cuts out and looking at the burn marks and distortion of the heatsink on the back of the ICM i think it is dead but we shall find out when the replacement arrives.

Tomorrow it's time to cure the vibration for good with some good old fashioned brute force and ignorance, my favourite!

D

[citroenxm]

Is the fuel pump in the tank yur 2.0i one or a v6 one .. or are all lift pumps same spec?? Is it cutting out from over heating possibly if wrong spec? Just some thoughts..

[Dean]

I've not looked at it but it runs fine and it is spark I'm missing, the engine runs great and then just turns off, I am almost positive it is the Ignition module now.

I was speaking to my dad about it last night and I wondered what would have happened if this had failed while trying to sort the immo wiring out and the missing power supply to the injection relay, with the bad contacts thrown into the mix on the Ignition Module too, would have been a nightmare to figure out what was going on.

If I fit the new module and it fires straight up I will know that was the problem, I have replaced everthing else with the re-build anyway, rotor arm, distributer, coil and plugs are all brand new, its typical the one thing I didn't touch died.

D