MK1 C5 HDI issues

[xmexclusive]

Hi Ciaran

I think the dedicated microprocessors came into production cars in the early 1980's with the first generation of ABS.
Quickly followed by engine control units.
These electronic developments enabled Citroen to produce the production hydractive suspension in the late 1980's.
So virtually all XM's have at least one dedicated microcontroller.
By 1994 Citroen had the first multiplexed XM's in production with the ECU's talking to each other.
The fact that Citroen restricted all XM multiplexing to just some French production cars suggests it was not a quick or trouble free development.
Anyone who has tried programming particularly at machine code level quickly realises that code perfection is a pipe dream.
Proving it works and testing for bugs is usually actually "works most of the time" and " oh dear I thought we had found all the bugs before we released".
A bit more effort goes into the bug fixing where safety is involved.
Most of the public would find the "blue screen of death" standard of programming inappropriate from the ABS while trying to stop.

John

[Ciaran]

I suppose it's easy to criticise / be fearful of multiplexing as a lot of people are, but as you rightly say many things wouldn't have been possible without the rapid development of electronics.
When the XM and other cars of it's generation arrived with it's new-fangled electronic suspension, I suspect people were equally dubious.

Can't stand in the way of progress, although current modern cars seem to have passed a ceiling in terms of complexity / the ability of the home mechanic to diagnose them. Then again, perhaps the idea of ever being able to query and repair a Hydractive ECU at home was similarly unthinkable in 1989.

[White Exec]

While working (during the 1990s and later) for the world's leading graphics/printing industry supplier, our old-style electro-mechanical film and plate processors gradually gave way to computer-controlled machinery. By the late '90s, quite humble 'wet' processors sported motors, valves, solenoids, sensors, et al, all linked to a CPU. This allowed everything to work to incredibly close parameters, with minimal wastage of time and materials. Going one stage further, "andro-diags" allowed these CPUs to be interrogated and adjusted remotely . . . maybe by an engineer or specialist working from home, or even from his car. In some cases, the customer agreed to leaving his kit connected to the remote 'phone line permanently, and many problems were actually swatted before the customer became aware of them. Similarly, when breakthroughs (updates) in materials appeared, machinery could be reprogrammed to take advantage of the new developments.

The flipside of all this was that (a) customers were dependent on the service team to rectify many faults, and (b) the machinery was worth diddly-squit on the secondhand/cheapo market, where potential owners were unwilling/unable to maintain professional service support.

Parallels with the XM are obvious. Which is why we need our Club, its understanding, and its resources.

[Dean]

You got yhe right colour too.

D

[Ciaran]

Lucky guess then!

[Ciaran]

While working (during the 1990s and later) for the world's leading graphics/printing industry supplier, our old-style electro-mechanical film and plate processors gradually gave way to computer-controlled machinery. By the late '90s, quite humble 'wet' processors sported motors, valves, solenoids, sensors, et al, all linked to a CPU. This allowed everything to work to incredibly close parameters, with minimal wastage of time and materials. Going one stage further, "andro-diags" allowed these CPUs to be interrogated and adjusted remotely . . . maybe by an engineer or specialist working from home, or even from his car. In some cases, the customer agreed to leaving his kit connected to the remote 'phone line permanently, and many problems were actually swatted before the customer became aware of them. Similarly, when breakthroughs (updates) in materials appeared, machinery could be reprogrammed to take advantage of the new developments.

The flipside of all this was that (a) customers were dependent on the service team to rectify many faults, and (b) the machinery was worth diddly-squit on the secondhand/cheapo market, where potential owners were unwilling/unable to maintain professional service support.

Parallels with the XM are obvious. Which is why we need our Club, its understanding, and its resources.

Interesting Chris, I suppose it's in every industry and not limited just to cars.

Good point about the second hand value, anyone in the market for bargain machinery wants to save a few quid and it's completely understandable they wouldn't be willing to fork out for professional maintenance contracts in some circumstances.

Ciarán

[Ciaran]

Well Dean did it start behaving again or is it still amusing itself with the radio every night?

[Dean]

Not sure yet Ciaran, my laptop should be here tomorrow, the battery was put on trickle charge last night and i will see how its doing when i get home and try a reset tomorrow if i get the time.

D

[Dean]

Well i hooked the C5 up today and i didnt think it was possible to have so many fault codes from one car, there were and still are 3 perminant faults and 7 int faults. The fault log was full however with all manor of faults, the fault log was actualy full with pages and pages of faults that had to be cleared before i could clear the current ones for some strange reason.

The remaining faults are as follows.
Heater fan open circuit (dual zone heating) not an issue
Radio ariel input connection fault (no idea)
Post/pre heater control circuit positive short circuit

Now the last one is interesting because i removed the relay, unplugged its ecu plug and main power supply which then threw up a second perminant fault saying wiring harness open circuit but still kept the original fault of a dead short in the positive which is interesting. There is no fuse for the glow plugs as far as i can see but i ran out of time and will resume in the morning, i suspect the short will be the source of the battery drain also..........maybe.

There were faults for the bsi, and dash display (interupted positive supply), plus another which laid blame with the brake peddle switch com's but that cleared and never came back, the dash display still says brake failure however.

The BSI reset proceedure has enabled the car to start and the headlights are not flicking on and off, the windows are still a bit unpredictable however.

Any thoughts before i attack again tomorrow?

D

[robert_e_smart]

Bale it, and use your Lexia on a proper car