Citroen XM Forum

No, I must admit I haven't Norman. Too worried what else might break if I do

Had a lovely day out today. A Xantia V6 owning friend of mine and I went to the National Vintage Communications Fair up near Leamington Spa; a Mecca for all those who love old wirelesses. We journeyed up in my XM. V6 owner was impressed as it was the first decent journey he'd had in an XM..

Spotted a GSA and a late Xantia estate in the car park. Mine was the only XM though...

Sorry for the long absence Hopefully I'm back and able to look and catch up slowly on what has been happening here. Until now I've just not had the mental facility to concentrate on the forums. I open them, start reading and just loose the will to go on. So I close down and go and do something else that takes a lot less mental effort...

I've not had the mental ability to drive far either and because of that the Activa has been put away again Clutch and gears are just far too much to cope with at the moment still

There was no way I could even attempt such a trip such as going to Wetherby and back..

Things are still not right so please bear with me a little.

Anyway, yesterday I did manage something significant. I finally got the ELIT talking to the gearbox ECU on my XM I made up a custom lead and indeed as I suspected I established a dialogue by speaking S2 Xantia to it. The difference that the S1 Xantia and XM speaks to the ECU using only the K diagnostic line whereas the S2 Xantia uses both the K and L lines..

So the car definitely has an S2 Xantia ECU fitted.

The fault turned out to be a torque reduction fault whereby the ECU cannot signal to the Engine ECU to retard timing (and thus reduce torque) when making gear changes. The fault cleared and so far has not reappeared..

Looking at the circuits for both the S1 and S2 Xantia I see that on the S2 both K and L diagnostic lines from the engine and gearbox ECUs are linked together whereas in the S1 they're not, only the K line being linked.

I'm wondering if the ECUs talk to each other over the K and L lines?

The research goes on but I believe the Engine ECU and gearbox ECU may be incompatible with each other. Not to worry though as it doesn’t seem to cause much issue with driving but may explain whey the car feels very lively...

Now off to try and catch up on what's been happening. That's if the old brain will let me

Impressed I am! My brain would never be able to comprehend all that! Hope you're on the up again Jim! Glad to see you back.

captainhaddock wrote:Hope you're on the up again Jim! Glad to see you back.

I hope so too Jaap All I know is it's good to be back...

What I did there had been in planning for a while and took no brain power, just a bit of mechanical work to expose the wiring and a bit of work with a soldering iron... A bit of gentle stuff to get me back into the swing of things...

I drove the car today and although the bulb is out behind the gear display I'm fairly sure the fault has not returned... I might go out a bit later and pop the ELIT onto it...

Excellent result Jim.

russ92xmsed wrote:Excellent result Jim.

Not quite Russ, the saga goes on

Yesterday I noted that as far as I could see the gearbox faults were still clear so I tried popping the ELIT onto it to see with the engine running. Upshot is that I can communicate with the ECU and read and do everything on it now except read faults This is bizarre and I'm wondering if running diagnostic leads across the top of the running engine has induced enough interference into the lines to zap the ECU? It's odd as the ECU is still working perfectly as far as controlling the gearbox goes although I can see from the display it has a stored fault again and everything works diagnostic-wise except being able to read faults... Only an XM could do this

That'll keep me busy over the weekend. I have the whole of next week off so lots of time for car play.

I think, on reflection, it was yesterday, one of those days when the ABS light came back on in the Xantia V6 so that sensor I thought was OK wasn't in the end and my neighbour's boiler and electric shower packed in simultaneously. Sadly, nothing I could do as the boiler had a serious water leak from something internal to it and the shower had died of old age.

The good bits of yesterday was the vet only charging me a tenner for Fluffball's annual demat and an excellent meal Siany and I cooked in the evening; an absolutely epic thai green curry Actually it wasn't cool - the additional chilli and ginger saw to that

Hi Jim. If you're feeling up to it and aren't too busy there's the 'technical weekend' at Barry Annels this weekend.

That's an annoyance Jim. Typical...
Hope you get to the bottom of it. This all sounds like technology from the 90's that never seemed to work!

Remember that TV program Bugs.... I think it was....pure fantasy!

My you know what is still off.

russ92xmsed wrote: Remember that TV program Bugs.... I think it was....pure fantasy!

Bugs Russ? How can I ever forget Bugs..... My wife went into labour whilst watching an episode and 4 hours later Siany joined us in the world That was over 18 years ago now....

Got it sorted. I'd well and truly zapped the gearbox ECU. Even a re-initialise wouldn’t revive it. It works absolutely fine and can be initialised but the fault memory is kippered. Any attempt to access it causes the ECU to shut down! But it till works fine as an ECU otherwise. Most odd...

That'll teach me to try to read faults with the engine running and leads draped all over the engine

I swapped it experimentally for a 406 V6 ECU I had knocking around that came with a gearbox I bought a few years back. It works a treat No faults. The old one was a Xantia one as confirmed by the part number. The 406 one I had is useless for the Xantia as it doesn't implement the shift-lock function (locks the lever in P until you apply the brake) but this is not needed in the XM... So that's an otherwise surplus ECU made good use of.

So pleased was I that I set about replacing the blown bulb behind the gear indicator... It all seemed to be a nice easy job at first. The BoL is wrong in that you don't need to remove the steering wheel and cowls and the front of the dash comes off easily enough.. Then the instrument pod...

What fur-lined, ocean-going knob-jockey designed that? Poppers on the bottom and two almost inaccessible nuts holding the top of the pod. Pure bizarre madness madness that befits an XM perfectly

Still, bulb is replaced, the indicator lights up and no longer flashes.. Result

You don't need to undo the top nuts! Just pull hard, there are little balls on the end of the bolts that snap into a plastic socket.