Citroen XM Forum

I have been driving my Xm for 18 months and have only just realised it is in permanent 'sport' mode, S2 H4ECU. I kept thinking it was not as comfortable as the BX. Investigation has shown that at sometime in its life some cretin has added an extra wire to provide 12volts to both front and rear electrovalves. I don't know what faults the car had before, but it now certainly has two fried electrovalves. BTW. testing pins 1 & 2 on the white connector is not a conclusive test of the electrovalves because they are earthed via a relay that on my car was floating about behind the NS headlight. I'm in the process of replacing the mosfets and adding diodes to the H4 ECU but also need 2 working electrovalves, any offers? Incidentally, the rear centre sphere had silver paint on the lower side, the car is silver, does this mean that it was the original sphere? The only other possibility is that some extensive repair work was done that required spraying underneath the boot floor. Both scenarios seem unlikely, any ideas? I have also replaced an ABS sensor with a £20 Xantia one, I can't find any posts relating to this, has it been tried before? Kit

Hi Kit

Putting a permanent 12v supply on them will fry them, they run mostly on a PWM signal to keep them cool. I doubt the centre sphere is original unless you have a very low mileage - but you never know, many people don't realise that its the centre sphere that gives the soft ride and then wonder why its not better when the corner ones are changed. Can't help you with the sensor I'm afraid, I fitted second hand ones, in fact the complete rear suspension one side.

Peter

Kit wrote:I have been driving my Xm for 18 months and have only just realised it is in permanent 'sport' mode, S2 H4ECU. I kept thinking it was not as comfortable as the BX. Kit

Have always been saying I bet many people drive around not knowing their hydractive is not working, thus never quite seeing the actual comfort the car has to offer, and probably selling on to move to something else as they deduce the Citroen comfort "is all press hype". Or others saying "the hydractive is not as comfortable as the non-hydractive setup" -you see this even in french forums- when it's actually the opposite. Shame....So well done for confirming yours is not working!!! Took me about the same time living in doubt -not having owned a hydropneumatic car before-.

Maybe post the demand for e-valves on the "wants" section also?

Good luck with sorting it out!
George

the rear centre sphere had silver paint on the lower side, the car is silver, does this mean that it was the original sphere?

The sphere should be green without body paint on it.

Putting a permanent 12v supply on them will fry them

Thanks Peter, it was your earlier posts that alerted me to this fact. If this forum did not exist I would be up a creek without a paddle. Off to look for a poor connection on the Abs. The battery tray will soon know it's own way out!

Or others saying "the hydractive is not as comfortable as the non-hydractive setup" -

Hmm think i may be one of those people! But the xantia lx really is better! I drove 2hrs in the xm last night and my back was very painfull, as the suspension might as well have been replaced with wood. Every bump BANG BANG BOUNCE BOUNCE.
Really need to try this diode mod!

davetherave wrote:

Or others saying "the hydractive is not as comfortable as the non-hydractive setup" -

Hmm think i may be one of those people! But the xantia lx really is better! I drove 2hrs in the xm last night and my back was very painfull, as the suspension might as well have been replaced with wood. Every bump BANG BANG BOUNCE BOUNCE.
Really need to try this diode mod!

I would agree, a non hydractive is always going to ride better than a hydractive that isn't working properly, if you don't want to corner at 60 mph and your hydractive is problematic - fit non hydractive spheres and forget about it.

Peter

If you can find a someone scrapping a Xantia VSX or Exclusive these are the same electrovalves.

Steve.

Ill try the diode mod, then perhaps it will be electrovalve time
Dont really want to disable the hydractive, it was one of the allures of "upgrading" to an xm!

Hi Dave,as the posts here point out, the centre spheres are the main influence on ride comfort and if good, then the diode mod is not the panacea for failed electrovalves.Their purpose is to shunt the back emf generated during collapse of the magnetic field generated in the coil to earth away from the solid state devices in the ecu.If you have approx 4 ohms resistance across the e/v coil then it's ok.If you can hear them buzz then the ecu and the solid state devices are ok.Installing the diodes will only give added protection in the event the integral diode fails.George's hydraulic investigation makes it clear that low system pressure prevents correct openning and closing of the e/v pilot valve and thus the mode.This is generally down to either contamination of the fluid and therefore a build up of gunge in the pilot valve or galleries of the stiffness regulator, or faulty pressure regulator/pump.If the hydractive warning light self test is correct on start up, and you still suspect that it is an electrical fault then you will have to carry out the checks in the service manual which give a comprehensive guide to fault finding.Better still if you have access to a LEXIA,run the diagnostics, and take the car for a run with it plugged in.You will see the various sensor information and the e/v status as it switches between modes.If you do not have access to the service manual ,post again and one of us here will submit the electrical fault checks.
robertm