Front Hydractive Electro Valve Fault

[rory_perrett]

Recently got a Lexia and I am showing 3 faults that I can’t shift.

One is a permanent fault on the front Hydractive Electro valve. The car is in permanent hard mode. I have done the diode mod and both front and rear valves are showing electrical continuity and a resistance of 4.5 ohms. If you do citrobics, during a rise or fall the rear valve momentarily switches and the car goes into soft mode for a second or so before going back to hard.

Does the ECU have any way of knowing what the electro valve is doing other that knowing there is electrical continuity? If electrical continuity is the only test, and from the plug it looks like that is OK does this suggest it is and ECU problem?

Rory

[DickieG]

What are the other two faults? Are they part of the Hydractive system?

Are the electrovalves buzzing?

When you go into "Perameters" what readings is it showing?

[rory_perrett]

DickieG

Other 2 faults are MAF P0100 and Pre-post Heating Circuit P0380.

I can hear a valve, not sure whether it is one or both - something to be investigated.

Parameters are showing 0 on both valves and Hard Mode.

Occasionally the rear valve parameter briefly shows 1 and the car momentarily switches to soft, almost straight away the rear valve reverts to 0 and the suspension is shown as back in Hard mode.

Rory

[xantia_v6]

Try replacing the electrovalve. My rear electrovalve registered a permanent fault, although it still worked intermittantly, it had a high internal hydraulic leakage. I don't know how the ECU deduced that it was faulty, as the resistance was OK. Maybe it measures the rise-time of the current through the inductor? A replacement valve from a scrap-yard fixed all the symptoms.

[rory_perrett]

Fortunately I have a spare valve and ECU so I could do a bit of changing about. Time and money are both a bit tight at the moment so I’m a bit loathed to start messing when the car is still useable. Did wonder if it needed the “spring stretch” repair detailed in other threads which seems to help revive the valve functionality.
Rory

[DickieG]

If you have a spare ECU then it's worthwhile swapping it but make sure (check the date printed on the front of the ECU) it's from the series of Xantia as yours as in S1 or S2 as they are not fully compatible.

As a thought are all the sphere pressures correct including the anti-sink/Hydractive ones? IIRC low sphere pressures can stop the electrovalves operating correctly.

Re code P0380, that's quite a common code which refers to duff glowplugs.

[rory_perrett]

DickieG

ECU is from a 1998 series 2, part numbers appear to be the same so should be OK.

What you say about the spheres is quite pertinent; the front accumulator has been on about 4 years the other 3 at the front 2 years. The rear ones are an unknown. Were on the car when I got it and the centre sphere is a grey “C5” one which may be an original. I learnt years ago (the hard way) that replacing a faulty component with a new one doesn’t necessarily mean that the new one isn’t also faulty. Given that the “spare” bits I have came off a car that had done 225k miles may not be in the best of shape.

Unfortunately, I don’t have a way to test spheres and, much as I would like to I’m not really in a position to change the rear ones just in case.
I suspect there may be some other problems in the suspension. When moving from high to low setting, when the car momentarily switches the rear electrovalve to soft this causes the front jump up.

Will try the “free” component changes first and go from there.

Cheers

Rory

[CitroJim]

When moving from high to low setting, when the car momentarily switches the rear electrovalve to soft this causes the front jump up.

That's normal on a Hydractive car Rory. It's not actually switching but rather the sudden change of pressure in the main hydraulic circuits causes the anti-sink valve to momentarily operate...

It's only a worry if the same happens when bouncing the suspension enthusiastically when at normal ride height.

[rory_perrett]

It was the ECU what was faulty - easy fix. Changed the ECU and got a different set of faults on the Lexia, presumably stored from the previous car. Anyway all faults cleared and suspension back in soft mode.

As a side issue I have had a look round the garage and reckon I can build a sphere tester with what is lying around in there.

[Chris570]

As a side issue I have had a look round the garage and reckon I can build a sphere tester with what is lying around in there.

Do it, I did