Wanted XM MK1 Service Manual, Multiple Electrical/suspension problems

[citroens]

John,
many thanks for I am now clear as to the number of electro valves and the series 1 or the MK1 had only one electro valve.

With reference to the fdv, I really need to see step by step pictures as well as write up and or a video for me to tackle it.

I am still also wondering with reference to the 2 Electro valves for the MK2, are these latter ones driven independently?

i.e. either the front or the back of the car is stiffer? Or just a different way of controlling the flow from the center accumulators, I am wondering as this is quite interesting. Also wondering the purpose behind this latter setup.

I also know that some XMs came without the Hydractive suspension, i.e. they were simply Hydro pneumatic, has anyone seen such an XM?

I had by mistake ordered 2 x rear complete cylinders for the XM Estate and I have them, only they look exactly like the CX Estate rear suspension cylinders.

sorry for the many questions

sincerely

cheers

Prakash

[xmexclusive]

Hi Prakash

The two electrovalves in the Hydractive 2 suspension are driven by seperate circuits in the suspension ECU.
With the new ECU Citroen also chose to use a solid state relay as the driving device.
These electronic relays tend to suffer failure and burn out problems.
Soldering iron repair work not just plug in a new relay.
Because each circuit can have its own faults, mechanical, hydraulic and electrical, it actually makes fault finding much harder.
With these later Hydractive 2 XM's many owners and maintainers give up the fault finding an fit the softer comfort spheres moving the cars closer to Non Hydractive.
There were no Non Hydractive XM's supplied to the UK but i know a man who choses to convert troublesome XM's.
Citroen took this electrovalve seperation a stage further with the Xantia Activa by adding a third electrovalve and driver circuit.
Citroen also added Constant Height (anti-sink) to the Hydractive 2 on later XM's.
I will see if I can find some drawings of the hydraulic layouts.

CX's are outside my area of interest so do not know about the rear cylinders.
XM cars can have two sizes of rear cylinder.
The enlarged the piston size a little with the Mk2 XM.
All XM estates are the same size.
It is important not to mix the cylinder sizes across the axle on an XM.

John

[citroens]

Hi,
I feel sorry for the series 2 XM owners and repairers for the solid state relay semiconductor devices used in the latter XMs.
Personally I would have not used the comfort spheres at all, what I would do is to use an external pwm power supply that would activate the ev/s, it really isn't hard.
I plan to make this pulse width modulation power supply and attach it to the ev via a double pole single throw switch and or use external relay that will allow me to activate the soft mode without changing to comfort spheres.

In the meantime, I have ordered a good working FDV, I will also order the kit from Citroen, I am told that they are still available, if not then I have heard that they are available at the GSF.

I am not sure if the fdv from the BX is the same as the XM, also I found a complete
Methodology at a BX site, shows in depth picture by picture as well as how all the parts are attached.
I hope that I don't get in trouble whilst I post a link here.

bxclub.co.uk/forum/viewtopic.php?t=2865

Should be fun to work with this.

Prakash

This post has been edited by citroens on September 01, 2012 06:25 am

[robertmnorton]

Hi Prakash, the PWM driver circuit for the xm hydractive 1 is well documented (albeit the text is in German) and is a straight forward approach to the manual mode selection of stiffness. I do not know of anyone on either of the forums that has installed this and look forward to your results.
robertm

[citroens]

Hi Robertm,
I wouldn't mind having a look at the German document, where may I obtain this?
I will have it translated , though there are a vast array of readily made pwm circuitry, it is just a matter of finding out the maximum and the minimum current draw of the solenoid as used in the XM ev.

I may even be able to use the existing circuitry that are the outputs(housed inside the Hydractive module) for the solenoid, thereby eliminating the extra add on external pwm circuitry.

When I get this underway, my Sport/Auto switch will have a third mode named comfort or a forced mode ev 'on'. This way I have the option if I want comfort or Auto/ Sport without the usage of the comfort spheres.
Also may aid in troubleshooting...

Prakash

[robertmnorton]

Hi Prakash, file posted in Hydraulic issues as "dc to pwm".
robertm

[citroens]

Hi Robertm,
I forgot to say thank you.
I also didn't realize it that I was still in the introductions thread.

cheers

Prakash

[citroens]

No worries.
I would like to express thanks for the Service manuals arrived last week from Norrie.
Thank you Norrie, your discs are well documented, also I like them in the pdf form as I am using an older Apple Mac.
I am almost done making my pwm from using a 555 timer,I will post this in the hydraulic section when I am done.


Cheers

Prakash