XANTIA HYDRACTIVE HELP

[davygr22]

Looking for some guidance with possible issue on my recently acquired Xantia - it is 1999 HDi Exclusive with Hydractive 2 suspension.Although mileage is relatively low @ 67k I have just replaced all eight spheres - the four wheel strut spheres had been renewed at some time,however the Hydractive front & rear regulator spheres appeared to be ruptured when I removed them as there was a huge gush of gassy LHM fluid from each on removal.I have fitted the diode repair kit as on previous Xantia's I 've owned.When I got the vehicle I noticed that the Hydractive switch on the dash does not illuminate its little warning 'on' lamp when the button is pushed.
The ride does not appear unduly harsh,but I suspect the front is a trifle firm - I can't hear the electrovalves buzzing when I open the driver's door.I know there can be issues with the Hydractive regulators - diode switch & jammed valves!!
Has anyone got some tests I can conduct to attempt a nailing down of the issues? - I don't have a Lexia!!
Is it possible for one regulator to be problematic( ie front only)? Is the Hydractive electrical system protected by relays/fuses other than under dash panel fuse No3 10A as detailed in the vehicle handbook?
Am I correct in assuming that the Hydractive default mode is 'firm'? If the vehicle is stuck permanently in 'firm' mode,just how harsh will the ride be?
I've not encountered this set of circumstances on other Hydractive Xantia's I've owned - if the Hydractive regulator spheres had been ruptured for a prolonged period,could this have caused some of the problems.

Thanks everyone!!

[Peter.N.]

You are correct in your assumption the the default mode is hard, the easiest way of checking whether its working or not is to bounce each corner of the car when its been standing for a while, then open a door and it should become considerably softer all round, more noticable at the rear, you should have at least twice as much movement in soft mode. You should hear a quiet 'clunk' when the system switches.

Peter

[Mandrake]

Another test is to measure the voltage going to the electrovalves, you can either measure where your diode modification kit is connected, (presumably in the wiring loom inside the plastic ECU protection box) or by unplugging the electrovalve. If you unplug the electrovalve you'll need to connect a 100 ohm resistor in its place as a load in addition to your volt meter or the ECU will detect a fault.

If the ECU detects a fault (open circuit, short circuit, faulty reverse diode etc) it will shut down the output on BOTH front and rear. If the electrovalves are being signaled to activate you'll see 12 volts for half a second as they engage, then dropping to around 3 volts average. (Pulse width modulated)

Another handy trick when diagnosing intermittent hydractive systems is to connect an LED through a 100 ohm resistor to one of the electrovalve supplies! I had such an LED tucked up in the top right corner of the dashboard near the windscreen fed via a wire running through the door jam and under the corner of the bonnet into the ECU housing for a long time when I was learning how the hydractive system worked, its quite informative seeing the light go on and off in response to driving stimulus.

I'm thinking of fitting the same LED to my V6 - I'm beginning to suspect it has intermittent hydractive issues that is causing it to revert to hard mode a lot more than it should - possibly a faulty power supply to the ECU as I've noticed the clock frequently resets to midnight and the interior fan sometimes goes off then comes back on again a few seconds later while driving, often in response to hitting a road bump!

Another thing it was doing yesterday while working on the car with the boot open and the motor off was that the electrovalves - which should stay on for 30 minutes when the boot is open, were going off, then back on again, then off, intermittently and randomly for quite a long time.

As to how a Xantia feels stuck in hard mode - it looses its wafty magic carpet ride, but I wouldn't call it harsh, its no harsher than any normal car, but with fairly tight handling. If you didn't know what a Hydractive Xantia was supposed to feel like and were used to conventionally sprung cars you might not notice it!

PS double check that your diode repair kit is not connected with the wrong polarity or going to the wrong wires...Series 1 and Series 2 Xantia's use different colours for the electrovalve wires... from memory they're white in Series 1 and something else in Series 2.