need help with c5 lexia diagnostics

[homer jw]

hi does anyone have a lexia dignostics kit who would be willing to help me will pay a fee and be entirely grateful changed gb oil but car is still in limp home mode need to decide if its beyond repair though would like to keep on road as car has been very good otherwise im in strathaven lanarkshire scotland ml10 phone me on 0-7-8-2-7-8-7-0-9-0-0 0-1-3-5-7 -5-2-9-0-9-1 or pm me whatever suits you

[myglaren]

Lexia owners are few and far between in Scotland.

A map with them on is in this thread

ETA: I see you have already been there

[homer jw]

anybody still on forum in scotland trying to pm xantia colin and dhall cant seem to pm them have they left site

[HaydnR]

I live in Fife and have lexia but won't be back home for three weeks.

[homer jw]

that would be great im in no rush whenever suits you hopefully speak soon when u can manage much appreciated jw cheers

[Mandrake]

I'm just in the process of buying a Lexia 3 for my Xantia, hopefully this week. (I'm waiting on the supplier getting more stock in)

I'm in Coatbridge so if you're still stuck by the time I have it up and running I may be able to help. I don't have any experience with Lexia diagnostics (yet!) but I'd be willing to give it a try, especially if any experienced Lexia owners have any tips on what to test and look for on this type of gearbox fault...

[The Birdman]

Take a look at Jims videos on you tube , it`ll give you an idea -

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[Mandrake]

Thanks Birdman, I've watched those videos already.

I've worked in IT all my life so I doubt I'll have any trouble installing and figuring out the Lexia software, what I meant is that I have limited understanding of the fine workings of an automatic gearbox, and no experience in diagnosing or repairing one so whilst I might be able to extract fault codes from it I wouldn't necessarily have any idea of the implications of particular faults in the gearbox, or what could be done about them.

So it was more a plea for any advice on diagnosing the limp home fault, likely causes and their possible solutions etc to help interpret the severity of any fault codes found...

[hirsty]

From my delvings into the Xantia AL4 autobox, I believe there is a requirement to reset the oil wear counter after changing the oil. I believe failure to do this can result in limp home mode. This needs to be done with a Lexia.

Keith

[homer jw]

soundsgood mandrake any help greatly appreciated let me know when it suits you thanks to everyone with there help and advice jw

[Mandrake]

Hi guys,

Just put the Lexia on homers car, the fault codes that came up were vehicle speed information coherence, and slipping clutch/brakes.

It looks like its being caused by low oil pressure. Doing a slow test drive down the road the oil pressure starts off normal around 2.5 to 4 bars (oil pressure equal to selected pressure) but quickly starts dropping away, when it gets below about 1 bar the clutches slip and no power is transferred.

At that point even when idling in neutral selected pressure (wanted pressure?) is 2.7 but actual pressure is around 0.2 to 0.4 bars. Anyone have any ideas on what might cause the pressure to be normal when first started then drop away rapidly after only a few seconds of gentle driving ?

[DickieG]

Anyone have any ideas on what might cause the pressure to be normal when first started then drop away rapidly after only a few seconds of gentle driving ?

If the car has done 100k+ miles and not had regular fluid changes my guess would be a blocked filter within the gearbox, I presume that when under load there's a greater demand for fluid but the flow is being restricted by a blocked filter.

[Mandrake]

Just tried an idle test, it took about 4-5 minutes for the pressure to drop gradually from 2.7 bars to 0.2 bars, lifting the revs a bit made no difference to the falling pressure. When driving along the road in 1st/2nd it dropped within a minute or so. As far as we know the oil level is correct after the recent oil change, and the symptoms were the same before the change anyway. Mileage is about 108,000 miles.

So a blocked oil filter is a candidate then ? What sort of job is that on an AL4 ?

[CitroJim]

So a blocked oil filter is a candidate then ? What sort of job is that on an AL4 ?

Not necessarily, if it starts off OK and falls it's possibly more likely the electrovalve that controls oil pressure. Addo knows more than I do about this as my AL4 knowledge is very limited.

I'd be inclined to change the fluid first-off and repeat the tests.

Running it with slipping bands and clutches is going to do it no good at all. The clutches will shed material which will end up in the oil and then the filter.

I believe filter replacement is the same task as the 4HP20; a full strip job. It would make sense if you do this to do a full rebuild, paying very close attention to the valve block.

[Mandrake]

Jim, as mentioned earlier in the thread an oil change was done a few weeks ago.

Don't worry, he hasn't been driving the car with slipping clutches, its not mobile. It will only work about 50 metres up the road with gentle driving then the clutches disengage and there is no motive force whatsoever. The Lexia shows the pressure normal to begin with (actual pressure equal to selected pressure, and I saw developed pressures as high as 4.5 bars during 1st/2nd gear with forward motion) but then it starts dropping away, when it gets to about 1 bar the clutches let go and there is no drive at all. With slow careful driving (about 15mph max) the pressure dropped below 1 bar within a minute.

When idling it took 2-3 minutes before the pressure started dropping, then over the space of about another 2-3 minutes it dropped progressively from 2.7 bars down to about 0.2 bars, where it would stay until the engine was turned off for a few minutes. Engaging drive or reverse had no effect while stationary if the pressure had already dropped this low.

If the engine was only turned off for a short time the pressure would not recover, but if it was turned off for several minutes the pressure upon next start would be back to normal, but then fall away again with time just like clockwork. Hopefully that provides a few clues.

I'll post the Lexia fault codes in the next couple of posts. Some of the fault code readings are bizarre, reporting the fault occurring at a temperature of -50 degrees (yes the oil temperature sensor is working ok in the live data)