Hydractive Repair Kit

[CitroJim]

Browsing e-bay just now, I came across this...

http://cgi.ebay.co.uk/CITROEN-XM-SPHERE ... dZViewItem

Quite amused me. I guess for £30 you get a nice box with a couple of diodes in it

One thing, it will work if you have the classic electrovalve problem but if you're half-handy with a soldering iron and have an electronics shop nearby the same thing can be done for less than 30p

[rowanmoor]

It all depends how you value your time and your soldering skills. There are plenty of people (including me) who value the time taken to do a good soldering job plus the research to find the correct wires for their car at far more than £30.

£30 for a ready made professional looking kit, plus the research handed to you on a plate and a few minutes to connect up with Skotchloks is a rip off for anyone with time on their hands who is regularly under the bonnet, but a good deal for people who struggle to find the time to change a headlight bulb or wash the car.

You would probably be surprised how many people have brought the kit after reading about it in a thread containing the research.

[CitroJim]

Very true Rowan,

I'm terribly guilty of not seeing the wider picture. I'm an electronics engineer by trade and spend a lot of time under my bonnet and playing.

I forget there are those who are not and it has to be said, £30 represents excellent value compared to taking the car to a dealer and having the offending electrovalves replaced

I must say, scotchloks apart, it looks a very professional kit. Personally, I dislike scotchloks with a passion

A nice addition to to this box would be a couple of LEDs to show the electrovalve status. This weekend, if I find time, I'm planning to put a row of three LEDs (three as the Activa has three electrovalves) on the dash to show mine working.

Here is a link to a post by Mandrake showing how to fit the diodes. It is half way down the second page of this thread. Tricky I agree if you're not confident with electronics and looms...

http://www.frenchcarforum.co.uk/forum/v ... c&start=15

[rowanmoor]

I have no problem with the electronics side. Almost ended up in the same trade as yourself, but veered into a software slant part way through my degree. It is purely the time I have a problem with . Others may have the time, but are not so sure about electronics.

Hopefully, later in life when kids are a bit older and job less demanding I will get to the point that time is not such an issue for me and I would not dream of paying someone else to do that sort of work for me.

I dislike scotchloks as well. They are easy to fit, but I have had a few that did not want to give reliable connections. Possibly because the wire was not quite big enough - not sure really. Then others that cut the wires clean in half after a few knocks of the loom. I guess they are just a bit sensitive to having the correct size on a wire - but then what if the 2 wires you are connecting are different sizes...

I do feel the ECUs should have a test mode whereby the dash light becomes a Hard/Soft indicator rather than a Normal/Sport indicator. You would need a couple of test modes for the Activa of course.

[Mandrake]

Interesting find...

The only thing I would comment on is that it's important to determine whether the system is in fact sticking in the hard mode - which can be done with a simple bounce test to compare hard and soft modes after known good spheres are fitted. (Otherwise someone might buy one of these boxes only to find that it doesn't have any effect)

Soft mode being while the engine is idling, and hard mode being 30 seconds after the engine is turned off and all doors are closed.

Other possible causes for harsh ride are balljoints, arm bearings, and air leaks on the pump input, and all of the above can cause more "harshness" than simply being stuck in the hard mode all the time, as the hard mode is not actually "harsh" but rather "firm".

A nice addition to to this box would be a couple of LEDs to show the electrovalve status. This weekend, if I find time, I'm planning to put a row of three LEDs (three as the Activa has three electrovalves) on the dash to show mine working.

Unless theres some bizare fault, you'll find the front and rear electrovalves switch at exactly the same time. It's possible that the Activa electrovalve switches under different conditions though - I would be interested to hear the results of that!

Also, from personal experience with the "faulty diode" problem, the LED will often not reveal it - on mine the problem seemed to be a dryjoint on the diode (inside the moulded coil casing) rather than outright failure, causing a random amount of resistance in series with the diode which seemed to vary with heat or vibration.

When the diode was playing up, quite frequently the electrovalve would leave the suspension in hard mode even though the LED was lit, so a lit LED is no guarentee that the electrovalve is physically activated! (One clue I did notice though is the LED often cycled between bright and dim at random)

What the LED will tell you is whether the ECU is behaving itself, and if the electrovalves are completely faulty, but not a lot in between.

Regards,
Simon

[rowanmoor]

The other thing the diode fix / kit is useful for is preventative measures. If your electrovales are 10+ years old then failure is a posibility. Better to add new dioes in the system at low cost and relative ease before the ECU starts to burn out components because the existing ones have already failed. You then don't need to worry as much for the next few years.

However, it will have no effect on current ride in that case.

[Mandrake]

I agree about it being a good preventative measure.

Even though I ended up replacing the electrovalve with the faulty diode, I left the two diodes (that I pictured) fitted in the wiring loom just in case...

Regards,
Simon

[CitroJim]

Activa electrovalve switches under different conditions though - I would be interested to hear the results of that!

That is one reason I want to have some LEDs on the system Simon I'll come back as soon as I know for sure. In theroy, the Activa Electrovalve should normally be in such a state that the Activa Balancing Sphere is in circuit (bad choise of words) in the same was as a Hydractive Sphere is in circuit in soft mode. My belief is that the Activa Balancing Sphere is isolated under hard cornering when the Roll bar needs to be at maximum stiffness. What I cannot get an answer to is if the Activa Electrovalve is normally operated or normally off. I have never heard mine make any sort of noise and the LED will very quickly tell me when it should operate. I'm also interested to know if the Activa Electrovalve is checked in the same way as the Hydractive Electrovalves when the HA ECU goes through its self-test routine when it boots.

I also want to test a personal theroy (may be rubbish this ) that if you go over a speed hump under power or brake at the hump the HA system will switch to hard mode whereas if you go over a speed hump with trailing throttle the system will remain in soft mode. This is valuable as we have an awful lot of humps in the UK

Also, from personal experience with the "faulty diode" problem, the LED will often not reveal it - on mine the problem seemed to be a dryjoint on the diode (inside the moulded coil casing) rather than outright failure, causing a random amount of resistance in series with the diode which seemed to vary with heat or vibration.

I agree. My front HA Electrovalve clicked and hummed but was remaining in hard mode and with no distinct click on reversion to hard mode. An external diode resolved that problem perfectly. A good Electrovalve will click when it operates, then hum (the 1KHz pulsed holding current) and then click again as it switches off.

One sure way to prove a diode is to put an oscilloscope on it. A good diode will show a nice solid 12V peak-to-peak squarewave with good square corners when the valve is in the operated condition (after the initial 500mS "full 12V" operate pulse). A duff diode will make the squarewave look ragged with spikes due to the back-emf as the magnetic field collapses.

I did notice though is the LED often cycled between bright and dim at random)

Is this the ECU doing the occasional switch to ensure the Hydractive Sphere remains charged during extended periods in hard mode when the Sphere is isolated?

What the LED will tell you is whether the ECU is behaving itself, and if the electrovalves are completely faulty, but not a lot in between.

It will give a pretty display as you are driving as well

[DickieG]

I also want to test a personal theory (may be rubbish this ) that if you go over a speed hump under power or brake at the hump the HA system will switch to hard mode whereas if you go over a speed hump with trailing throttle the system will remain in soft mode.

Whether the suspension switches to hard mode or not over a speed bump is determined by the speed at which the suspension compresses (body movement sensor located on the front anti-roll bar).

Bear in mind that in any car (including steel suspension ones) that the smoothest method for negotiating speed bumps is to travel over them under power as this lifts the front of the car up and over the bump then reduces the rebound effect felt at the rear by 'pulling/elongating' the curve/rebound felt at the rear.

Here's a link to Jim's idea of the 3 LED's on an Activa http://translate.google.com/translate?u ... uage_tools

By the way Jim I've managed to get hold of a bottom bush on the rear Activa ram,,,,,,,,,,,,,,it came free with a shiny new ram, bargain @ £251

[Mandrake]

Activa electrovalve switches under different conditions though - I would be interested to hear the results of that!

That is one reason I want to have some LEDs on the system Simon I'll come back as soon as I know for sure. In theroy, the Activa Electrovalve should normally be in such a state that the Activa Balancing Sphere is in circuit (bad choise of words) in the same was as a Hydractive Sphere is in circuit in soft mode. My belief is that the Activa Balancing Sphere is isolated under hard cornering when the Roll bar needs to be at maximum stiffness.

Correct.

What I cannot get an answer to is if the Activa Electrovalve is normally operated or normally off. I have never heard mine make any sort of noise and the LED will very quickly tell me when it should operate.

Ok, I can answer that as I have a book with the info and just re-read it!

Contrary to what I expected it seems that electrovalve off = soft roll mode and electrovalve on = stiff roll mode! (Eg opposite to the normal Hydractive Electrovalves)

So it's only during tight cornering that the electrovalve comes on. So, if the electrovalve were to be faulty the result would be more than usual body roll under hard cornering. Because the roll corrector is active all the time it would still try to compensate for body roll even if stuck in the "soft roll" mode, but the maximum cornering forces it could compensate for before the body started rolling would be a lot less.

Also it looks like only 3 pieces of information are used for activating the activa electrovalve - road speed, steering wheel angle, and steering wheel turning velocity. (Using similar lookup charts to the HA2 electrovalves) Furthermore the rollbar is always in soft roll mode below 20Km/hr.

None of the other inputs (accelerator pedal, front brake pressure, and body movement sensor) play a role in this - which makes sense as none of those factors affect body roll.

So that means it is possible for the system to switch to Hydractive 2 hard mode without switching to stiff roll mode - this would happen for example under hard braking.

I'm also interested to know if the Activa Electrovalve is checked in the same way as the Hydractive Electrovalves when the HA ECU goes through its self-test routine when it boots.

According to the fault table in the book the result of the Activa electrovalve failing the self test results in permanent "soft antisway" mode, eg the rollbar stays in soft mode all the time, so the car will roll more on tight corners. This is opposite to the HA2 electrovalves which will fail to Hydractive hard mode.

It also looks like the Activa electrovalve failing doesn't have any effect on the main Hydractive 2 system and electrovalves.

In theory you could unplug the Activa electrovalve and give the car some stick around a tight corner and you should notice it rolling more, but I'd be weary of such a test.

The book I have has a very clear explanation of how the Activa system works - I'll try to scan it soon when I get a chance and put it up. (It's about 30 pages )

I also want to test a personal theroy (may be rubbish this ) that if you go over a speed hump under power or brake at the hump the HA system will switch to hard mode whereas if you go over a speed hump with trailing throttle the system will remain in soft mode. This is valuable as we have an awful lot of humps in the UK

Well, hard braking will put the HA2 system into hard mode for as long as you're braking hard and as long as the road speed exceeds approx 20Km/hr, but with acceleration its not so much acceleration, but rather movement of the throttle pedal (displacement and velocity) that triggers the hard mode, so if you were to give the throttle a flick just before hitting the bump, yes it would switch to hard mode.

The body movement sensor will detect a humpback speed bump and trigger hard mode too - for long enough for the entire car to pass over it. I find on the typical wide humpback speed bumps if I'm doing more than about 30Km/hr the body movement sensor will switch it to hard mode.

Also, from personal experience with the "faulty diode" problem, the LED will often not reveal it - on mine the problem seemed to be a dryjoint on the diode (inside the moulded coil casing) rather than outright failure, causing a random amount of resistance in series with the diode which seemed to vary with heat or vibration.

I agree. My front HA Electrovalve clicked and hummed but was remaining in hard mode and with no distinct click on reversion to hard mode. An external diode resolved that problem perfectly. A good Electrovalve will click when it operates, then hum (the 1KHz pulsed holding current) and then click again as it switches off.

Yeah, when the diode fails you hear the hum (sometimes) but not the mechanical click, which is pretty loud when they're working properly.

One sure way to prove a diode is to put an oscilloscope on it. A good diode will show a nice solid 12V peak-to-peak squarewave with good square corners when the valve is in the operated condition (after the initial 500mS "full 12V" operate pulse). A duff diode will make the squarewave look ragged with spikes due to the back-emf as the magnetic field collapses.

True, but not many people chasing this problem are likely to have portable oscilloscopes (I've actually got one, but havn't tested this as I can pretty much predict what I'd see)

I did notice though is the LED often cycled between bright and dim at random)

Is this the ECU doing the occasional switch to ensure the Hydractive Sphere remains charged during extended periods in hard mode when the Sphere is isolated?

It seems to be the ECU's response to a marginal diode fault - it keeps cycling between the full 12v and the PWM 3v about once per second. Hence the LED going from bright to dim and back again.

Another thing to note is that the load from the LED itself is enough to fool the ECU into thinking the electrovalve is ok and keeping the power applied even if the electrovalve isn't connected at all!!

So connecting LED's prevents the ECU's hard mode failsafe (in the case of faulty electrovalves) from working properly - so beware.

What the LED will tell you is whether the ECU is behaving itself, and if the electrovalves are completely faulty, but not a lot in between.

It will give a pretty display as you are driving as well

So long as you put them somewhere so you can see them without taking your eyes off the road!!! (I put mine up near the pillar between the drivers door and the windscreen)

This is my complaint about the location of the Normal/Sport mode button in series 1 Xantia's being in front of the height lever - VERY dangerous to look down at it while pressing it while driving to see which mode you're in, and I guess Citroen thought so too when the moved it to the dashboard in Series 2...

Regards,
Simon

[CitroJim]

Simon,

Very many thanks indeed, that is excellent My Activa understanding has greatly increased

My first thought was to put the LEDs in the back of the oddment tray where three holes are present. These I suspect held the switches for the "Blues and Twos" in the cars previous life. Not a good place as it will take too much of a deliberate look to see them. I'm now looking at mounting them in a slim weatherproof box on the bonnet edge near the drivers washer jet. They'll be right at eye level then. I'm going to use two green LEDs for the Hydractive and an Amber one for the Activa.

A good point on the LEDs possibly fooling the HA ECU self-test. It is, I think, worth having an ability to quickly and easily disconnect them so that if any doubt exists, they can be taken out of the equation. One of my weekly checks, along with fluid levels, Citarobics etc, is to listen to both HA electrovalves on door open and close and confirming they're working by working the suspension up and down.

Agreed on the switch although it is still not that easily visible on the MK2. The LED in it is not that bright either. It still takes a deliberate look at it to see what mode it is in. Maybe I'll wire a repeater LED up with the Hydractive and Activa LEDs.

[CypherPunk]

Is there anyway to tell for certain if an electrovalve is working correctly? I’ve replaced all of the spheres recently on my Xantia V6 and while the ride is definitely improved, it’s still not as good as my old Xantia 1.8 LX.

If I try pushing down the front and back of the car after it has been sitting for 30 seconds with the doors closed the front and back are very hard indeed and are practically impossible to move. If I open a door I can hear a click from the front and back of the car and a humming noise, now when I try pushing down the back of the car it’s a lot softer, however the front of the car is still rock solid and impossible to move.

[Mandrake]

Is there anyway to tell for certain if an electrovalve is working correctly? I’ve replaced all of the spheres recently on my Xantia V6 and while the ride is definitely improved, it’s still not as good as my old Xantia 1.8 LX.

If I try pushing down the front and back of the car after it has been sitting for 30 seconds with the doors closed the front and back are very hard indeed and are practically impossible to move.

Sounds normal for hard mode - even when the strut spheres are fine, the damping is so stiff that it feels very stiff for a bounce test.

If I open a door I can hear a click from the front and back of the car and a humming noise, now when I try pushing down the back of the car it’s a lot softer, however the front of the car is still rock solid and impossible to move.

Did you start the engine again ? If it's been sitting for a while (even a couple of minutes) there may not be enough pressure left for the front to switch back to soft mode. Soft mode always has to be tested with the engine idling, not just opening a door.

Try again with the engine idling, and if its still very stiff at the front and you have recently replaced the front hydractive centre sphere then yes you do have a fault which might be electrovalve related.

Regards,
Simon

[CypherPunk]

Right, I’ve just gone out and tried bouncing the suspension with the engine running as I couldn’t remember if it was running before or not. With the engine running and a door open the back of the car was nice and soft as before, and the front was pretty much rock solid, even with all of my weight I could only move it about 1 cm.

I tried closing the door and leaving the engine running, but the car wouldn’t switch to hard mode, so I turned the engine off, closed the door and eventually heard a loud click as it switched into hard mode. The back of the car was now rock solid and wouldn’t move at all, the front of the car seemed pretty much the same as before, maybe slightly stiffer but I couldn’t decide if this was just my imagination or not, the difference definitely wasn’t as noticeable as it was on the rear suspension.

[AndersDK]

Even in hard mode it should be possible to press down on each wheel - like you press down a coil spring.
My pennies are on 2 shot front wheel spheres on your Xantia
Its got nothing to do with hard/soft mode working or not.