Xantia stuck in hard mode

[xantos]

I've paid attention to the electrovalves and this is what they do:

- click and buzzing for 10 seconds
- nothing for 10 seconds
- click and buzzing for 5 seconds
- nothing for 10 seconds
- then a few clicks and silence

Sometimes when I stop the car the back end suddenly "jumps" up, another time I can hear a sound like pressure is being released.
Yesterday the back end jumped up while I was driving... Quite a surprise

[Mandrake]

The symptoms you describe with random switching on and off of the electrovalves is classic symptoms of a faulty back EMF diode or a high resistance connection to the solenoid coil.

Do you have a multimeter and a copy of the Hydractive 2 training manual which includes pinouts of the ECU ?

(If not, its here: http://homepages.igrin.co.nz/simon/imag ... ive_II.pdf" onclick="window.open(this.href);return false; )

With both connectors unplugged from the ECU measure the resistance between pins 1 and 15 (front electrovalve) and pins 2 and 15 (rear electrovalve) on the white connector.

Unfortunately I don't have a copy of the Activa manual which also shows the Activa electrovalve, so I don't know what pin number it is, but it should also be checked.

The electrovalves should be about 4.8 ohms. If they are much higher than this (say more than about 6 ohms) then you have a faulty electrovalve coil or a wiring / connection fault.

If the coil resistance of both coils is ok you may have a faulty diode. Have you tried replacing your external diodes with new known good ones ?

[xantos]

I assume from this pic: that it's pin 9 that also needs to be checked.

[Mandrake]

Yes that appears to be correct, pin 9 for the Activa electrovalve, so check that one too.

[xantos]

I have measured the resistance between pin 1,2,9 and 15 and it shows 4,8 ohms. I also get voltage on two of the three diodes. Peak of around 12V and then 3V when the car is running. The third diode is not giving anything and I replaced it two times. Maybe it as something to do with the activa system and it comes on when driving.

When I cut the ignition and open the door I can hear the valves buzzing. When shutting the door they are buzzing for about half a minute and then stop. It's interesting that if I have the door open they are buzzing for quite a few minutes.

I have also noticed that when I start the car and when it's trying to come to the ride height the electrovalves are clicking every 1-2 seconds. The car is trying to rise and when the click comes in it stops. This happens about 30 times until the ride height is achieved. But the ride is still harsh even though the electrovalves are working. It was really a pleasant drive when I (wrongly) connected them to 12V. So it seems that the valves are in good condition and also the spheres. There must be another problem...

Yes the wonderful world of activa ownership...

[Mandrake]

I have measured the resistance between pin 1,2,9 and 15 and it shows 4,8 ohms. I also get voltage on two of the three diodes. Peak of around 12V and then 3V when the car is running. The third diode is not giving anything and I replaced it two times. Maybe it as something to do with the activa system and it comes on when driving.

The Activa electrovalve works opposite to the other two. It controls connection of the Activa balancing sphere - when the electrovalve is off (default during gentle driving) the balancing sphere is connected and the roll bar is soft. When cornering hard the activa electrovalve will turn on isolating the balancing sphere, stiffening the roll bar.

Therefore you will only see this electrovalve activate during hard cornering, never while stationary or straight ahead cruising. So its normal for you to not measure any voltage on this one while stationary.

When I cut the ignition and open the door I can hear the valves buzzing. When shutting the door they are buzzing for about half a minute and then stop. It's interesting that if I have the door open they are buzzing for quite a few minutes.

All normal behaviour. They will stay on when the engine is idling, with the engine off they will stay on for 30 seconds after the engine is turned off or after a door is closed. With a door open they will stay on for 10 minutes.

I have also noticed that when I start the car and when it's trying to come to the ride height the electrovalves are clicking every 1-2 seconds. The car is trying to rise and when the click comes in it stops. This happens about 30 times until the ride height is achieved.

Are you sure this is the electrovalves ? It sounds more like you have a flat accumulator sphere and that the pressure regulator is clicking on and off rapidly as the car rises...

But the ride is still harsh even though the electrovalves are working. It was really a pleasant drive when I (wrongly) connected them to 12V. So it seems that the valves are in good condition and also the spheres. There must be another problem...

Yes the wonderful world of activa ownership...

Don't give up, I'm sure you'll get it sorted with a bit of help from the forum Check the accumulator sphere because it sounds like this is flat, this will cause all kinds of problems with an Activa as they are more fussy about having a constant well regulated source of pressure to operate the Activa system as you drive...

[xantos]

I am sure (99%) it's the electrovalves. Because you can hear the clicking sound in the front and in the back of the car. When the car settles I can hear the accumulator sphere valve clicking for about once in a minute...

It's true that the spheres are in an unknown situation, but like I said the ride was very good when the valves were connected to 12V constant, so I think they are in solid condition.

[xantos]

Just measured the electrovalves... When they are energized the car jumps up and then they are being held at 3V for a couple of seconds and back to 0V again. And then again after a minute.

The hardest thing to do is keeping my nerves calm...

[Mandrake]

Just measured the electrovalves... When they are energized the car jumps up and then they are being held at 3V for a couple of seconds and back to 0V again. And then again after a minute.

The hardest thing to do is keeping my nerves calm...

Faulty back EMF diodes give this exact symptom. It only takes one faulty diode to affect both front and back suspension. I'll explain in more detail later as I have to be outside working on my own car while the sun shines...

[xantos]

But I have changed the diodes yesterday with new ones. All three of them. And the readings were just fine. When idling it was showing 3V all the time... Is something burning them out? Should I get 3A diodes?

[CitroJim]

Check the accumulator sphere because it sounds like this is flat, this will cause all kinds of problems with an Activa as they are more fussy about having a constant well regulated source of pressure to operate the Activa system as you drive...

Absolutely correct. The electrovalves need the correct hydraulic pressure as well as an electrical signal to opetrate and if the main hydraulic pressure is low then they'll not operate - simple as that.

If they click and hum under ECU control then fundamentally they're OK.

NEVER connect an electrovalve directly to 12v. They will not stand it for long and will burn out. They are designed to operate on a square-wave signal and not a constant voltage.

Don't forget the Activa has TWO accumulators. In addition to the main accumulator there is an Activa accumulator under the battery tray. This one is hidden and often forgotten. If flat then it will give your symptoms.

[xantos]

Yes I know that it's wrong to connect the electrovalves to 12V, but I have done it and the drive was really good (only had them connected for a few hours).

I don't understand this... You can hear the main accumulator sphere valve click once a minute. That shows the accumulator sphere is ok, right?

Is there a possibility that I have over tightened the pressure release valve and now the seat is damaged causing me problems?

Also intend to buy all 10 new spheres anyway. As I figured these would do fine: http://www.ebay.com/itm/10-SPHERE-NEUVE ... 0759596%26" onclick="window.open(this.href);return false;

What do you think?

[Hell Razor5543]

The Activa has a total of 10 spheres. There are the usual 4 at the corners, the accumulator sphere, and the anti-sink sphere. There are then the two Hydractive spheres, one at the front and one at the rear, and finally there are the two Activa spheres (again, one at the front and one at the rear). Other than this, I cannot help (but Activa aficionados will be able to give a lot more advice and information).

As CitroJim said, the Activa has TWO accumulator spheres. If either is flat you will have problems.

[taffy]

agreed i would change accumulator spheres as its what gives pressure to the system...wont cost much

[CitroJim]

Just to ad a bit more about electrovalves - they normally fail by leaking, either internally due to worn valve seats or externally due to corrosion. Neither will prevent the car switching to soft mode. I have known just one failed solenoid coil where I suspect the internal diode that normally goes open-circuit failed short-circuit.

If the valves are leaky internally then they will cause a high regulator tick rate which can be checked by pulling the hydractive ECU fuse to force hard mode (valves off/shut) and comparing the tick rate to that obtained when in soft mode.

Sometimes if they are really leaky you can hear a rush of LHM in the leakage return pipe from the valve when the engine is first stopped and hydraulic pressure falls.

You may need to check the main-line hydraulic pressure. For this a gauge will be needed to tee into the output of the pressure regulator. I made one for the very same reason that this thread is all about..

If the cut-in pressure is much below 145 bars then you have an issue.

Here it is in use: