C5 hydractive 3 electrical issue

This is the Forum for all your Citroen Technical Questions, Problems or Advice.

Moderator: RichardW

User avatar
white exec
Moderating Team
Posts: 7384
Joined: 21 Dec 2015, 13:46
x 1445

Re: C5 hydractive 3 electrical issue

Post by white exec »

I guess so. Marc or others here who know H3/C5 better would confirm.
User avatar
GiveMeABreak
Forum Admin Team
Posts: 26039
Joined: 15 Sep 2015, 19:38
x 2985

Re: C5 hydractive 3 electrical issue

Post by GiveMeABreak »

I did put a load of stuff up years ago, but here's the BHI hydraulic diagram for reference: Please note this is for the 4 Cylinder Engines of the Citroen C5 X7 (MK III) - not for 6 Cylinder Engined X7s:

BHI Role

The integrated hydro-electronic block ECU controls the following components:
  • The electropump unit and its electrovalves
  • The stiffness regulator electrovalves
  • The vehicle ride height
  • The stiffness
C5 X7 Tourer BHI Hydraulic Diagram A.PNG
"a" Suspension ECU.
"b" 32-way black connector .

Allocation of the channels of the black 32 -way connector
Channel No.Designation
A1Not connected
A2Body height sensor supply (Rear ) (+)
A3Not connected
A4Not connected
B1Not connected
B2Body height sensor supply (Before ) (+)
B3Not connected
B4Information RCD
C1Not connected
C2IS CAN High
C3Not connected
C4IS CAN Low
D1Body height sensor supply (Rear ) (-)
D2Not connected
D3Not connected
D4Not connected
E1Body height sensor supply (Before ) (+)
E2Line k information
E3Not connected
E4Body height sensor signal (Rear )
F1Not connected
F2Integrated electric motor control
F3Not connected
F4Front body height sensor signal
G1Not connected
G2Front hydractive electrovalve control
G3Front hydractive electrovalve supply (+)
G4Rear hydractive electrovalve supply (+)
H1Body earth
H2Rear hydractive electrovalve control
H3Not connected
H4+Battery
C5 X7 Tourer BHI Hydraulic Diagram.PNG
Key

"G" To the front and rear stiffness corrector solenoid valves.
"H" To the stiffness corrector (Rear ) (Input /Output ).
"J" To the stiffness corrector (Before ) (Input /Output ).
"K" LDS fluid return from the stiffness solenoid valves.
"a" Hydraulic pump motor.
"b" Suspension ECU.
"e" The suspension inlet electrovalve (Rear ).
"f" The suspension exhaust electrovalve (Rear ).
"g" Pressure accumulator.
"j" LDS fluid reservoir.
"k" Rotating plate.
"m" Delivery valve.
"n" Overpressure valve (180 bars).
"p" Inlet electrovalve (Before ).
"q" Exhaust electrovalve (Before ).
"r" Reservoir.

As far as the rear Firmness Regulator is concerned (as I think this is what you are interested in):

Modification of the stiffness
The suspension adapts its "firm" or "soft" statuses in relation to the following parameters:
  • Body movements (pitching, rolling)
  • Cornering
  • Acceleration
  • Braking
The stiffness is also adapted to the actual behaviour of the vehicle (For example):
  • Actual longitudinal and transverse acceleration
  • Hunting movement
  • Detection of significant wheel travel
When the "Sport" mode is selected, the decision thresholds are lowered.
N.B.: The "sport" mode can be "forced" by pressing the "sport" mode button, or can be determined by the system in relation to the style of driving.
C5 X7 Tourer Rear Firmness Regulator A.PNG
"A" : High pressure inlet (Integrated BHI ).
"B" : Return to the reservoir (Integrated BHI ).
(1) Rear firmness regulator.
(2) Rear stiffener regulator accumulator.
"a" Variable firmness electrovalve.
"b" Bleed screw(s) .
"c" Return spring.
"d" Hydraulic isolation slide valve.

Role
The rear firmness regulator permits modification and regulation of the firmness of the suspension on the rear axle.

Function

Operating statuses of the rear firmness regulator:
  • Soft status: All of the suspension accumulators are in communication; the overall volume of nitrogen used is the maximum
  • Firm status: The firmness regulator accumulators are isolated from the suspension; the suspension accumulators work autonomously with the suspension cylinders; the firmness is maximum and reduces body movement, roll and pitch
Soft Status
C5 X7 Tourer Rear Firmness Regulator B.PNG
"A" : High pressure inlet (Integrated BHI ).
"B" : Return to the reservoir (Integrated BHI ).
(1) Rear firmness regulator.
(2) Rear stiffener regulator accumulator.
"a" Variable firmness electrovalve.
"b" bleed screw(s) .
"c" Hydraulic isolation slide valve.
"d" Electrovalve slide valve.

Soft status:
  • The electrovalve is not supplied
  • The electrovalve slide valve "d" moves under the effect of the integrated hydroelectronic block supply pressure
  • The return to the hydraulic fluid reservoir is blocked : The pressure under the lower part of the hydraulic isolation slide valve is identical to that of the BHI
  • The upper part of the hydraulic isolation slide valve is identical to that of the BHI : The slide ("c") moves under the action of the integral spring
  • Flow of hydraulic fluid between the right hand and left hand suspension is possible : The hydractive 3+ sphere communicates with the suspension circuit
N.B.: In the rest position, the rear firmness regulator is at the soft status.
N.B.: The body height can be regulated in "soft status" operation.


Firm Status
C5 X7 Tourer Rear Firmness Regulator C.PNG
"A" : High pressure inlet (Integrated BHI ).
"B" : Return to the reservoir (Integrated BHI ).
(1) Rear firmness regulator.
(2) Rear stiffener regulator accumulator.
"a" Variable firmness electrovalve.
"b" Bleed screw(s) .
"c" Hydraulic isolation slide valve.
"d" Electrovalve slide valve.

Firm status:
  • The electrovalve is supplied
  • The electrovalve slide valve "d" moves and frees up the return to the reservoir and blocks the hydraulic supply from the integrated hydroelectronic block
  • The bottom part of the slide ("c") is at the pressure of the hydraulic fluid reservoir
  • The upper part of the slide valve is under pressure from the hydractive sphere 3+
  • The difference in the pressure at each end of the slide ("c") causes its movement
  • In its new position the slide ("c") blocks the passage of hydraulic fluid between the RH suspension and the LH suspension
  • The hydractive 3+ sphere is isolated from the suspension circuit
N.B.: The body height cannot be corrected in "firm status" operation.

Allocation of the channels of the 2-way connector
Channel No.Designation
1Rear hydractive electrovalve supply (+)
2Rear hydractive electrovalve control
Dunkah
Posts: 33
Joined: 17 Jan 2021, 15:41

Re: C5 hydractive 3 electrical issue

Post by Dunkah »

Hi Marc and Chris,
Firstly, really sorry about such a slow response to this, had a full on hectic couple of weeks at work and haven’t really found the time to think about c5 suspension….
Secondly..,. Thanks for all the tech info so far, very valuable indeed.
Here’s where I’m at with it now,
I got through to e-crofting about that magic box, had to wait a while as he was away for a week, he was very helpful over the phone but unfortunately he thinks his magic box is not going to work on a c5 as it’s designed for xantia and xm, he thinks the electronic side of things is too different on a c5.
Here’s a couple of thoughts on where I may proceed with this…..
I’ve got a spare suspension pump with ecu, I was thinking of swapping it in and hope that the ecu will possibly do a better job than the current one. Possible problem there is that if resistors or diodes are caput it could possibly damage the new ecu and I’m back to square one….
Also, now I’ve been into the valve block and witnessed the internals I was considering possibly just removing parts of the valve so that the spheres aren’t blocked out permanently. Lots of possible problems there I guess. I’d have no sport mode at all, there’s a possibility that the car could never read the suspension correctly and constantly be trying to correct it somehow……
Could possibly cause a situation where the height goes up and wouldn’t come back down, or vice versa or could possibly lose that function altogether.
I think my fist port if call though is to get my corner spheres swapped for new units, very difficult job so far, can’t find any way of getting a tool to it to undo them, I usually use a very big pair of stilsons but there no way that going to work here, thinking a oil filter tool maybe the way forward.
Any more thoughts at all from anyone, particularly the electronic side of things, will still be greatly received
Many thanks guys
User avatar
GiveMeABreak
Forum Admin Team
Posts: 26039
Joined: 15 Sep 2015, 19:38
x 2985

Re: C5 hydractive 3 electrical issue

Post by GiveMeABreak »

Be aware you can't just swap out the ECUs from another BHI unless they are from an identical vehicle - as the configuration will be different.

The Hydractive 3+ on a MK III is very different from Xantia as are the electronics.

I think you need to focus on the spheres first - as let's face it they are coming on for 14 years old now. If the ride is too hard then it could very well be the corners are needing replacing / and or the rear centre spheres too. That's where I would be focussing if it was my car. :)
Dunkah
Posts: 33
Joined: 17 Jan 2021, 15:41

Re: C5 hydractive 3 electrical issue

Post by Dunkah »

Yeah, spheres was my first consideration when I first got the car, did the centre ones no problem but the rear corners are a nightmare to get to, I’ll put a bit more effort into them and see if I can get them swapped.
With regard to the ecu, I recently started suspecting that as the electrical signal to the rear ev isn’t what it should be, it goes from 8v to 0v, apparently it should be 12v and 3v.
I’ll get onto the spheres first and hope that sorts it out.
Thanks again
tomassk8
Posts: 2
Joined: 23 Oct 2021, 18:31

Re: C5 hydractive 3 electrical issue

Post by tomassk8 »

Hi Dunkah, can you tell me how it turned out? I have a similar problem, but according to the description of how it works from GiveMeABreak, if EV didn't work, the car would still be in soft mode. A jammed EV would mean the car would not go up and down (if I understood correctly). If you change the center spheres, then in sport mode it disconnects and the car should be extremely hard (if the outer spheres are KO) Thanks
User avatar
GiveMeABreak
Forum Admin Team
Posts: 26039
Joined: 15 Sep 2015, 19:38
x 2985

Re: C5 hydractive 3 electrical issue

Post by GiveMeABreak »

@tomassk8:
All 7 spheres in use = Normal / Comfort mode.
With 3 Centre Spheres cut out of the circuit = Sport Mode
Dunkah
Posts: 33
Joined: 17 Jan 2021, 15:41

Re: C5 hydractive 3 electrical issue

Post by Dunkah »

Hi Tomassk8,
Been meaning to update this but been so busy lately just hadn’t got round to it.
Turns out it was just the spheres after all. Originally I thought it was the centre spheres, as they are the ones responsible for stiffness. New ones made no difference, along the way I discovered a couple of other issues, pretty much unrelated but it got me completely over thinking things. Just recently I finally got round to changing the corner spheres and now the car is back to its super comfortable magic carpet ride quality. So it really was as simple as new corner spheres....... they weren’t easy to get to, which was one reason I’d put it off for so long. Got em in the end though
User avatar
white exec
Moderating Team
Posts: 7384
Joined: 21 Dec 2015, 13:46
x 1445

Re: C5 hydractive 3 electrical issue

Post by white exec »

Glad to hear you've got a comfortable ride back again.

Just to clarify - the corner spheres provide the quality of the Firm ride. The system only goes Soft when the centre spheres are switched into circuit (by the electrovalves), by putting extra sphere (compressible gas) volume into the system. When they switch out (EVs go off), the ride immediately becomes Firm again.
User avatar
citroenguy
Donor 2021
Posts: 64
Joined: 21 Sep 2017, 18:05
x 21

Re: C5 hydractive 3 electrical issue

Post by citroenguy »

Have you screwed out the solenoid itself?
A common fault is that the plunger-thingy gets sticky from rust buildup inside.
Taking it apart and poloshing it with fine grit sandpaper seems to fix it
tomassk8
Posts: 2
Joined: 23 Oct 2021, 18:31

Re: C5 hydractive 3 electrical issue

Post by tomassk8 »

white exec wrote:
24 Oct 2021, 08:22
Glad to hear you've got a comfortable ride back again.

Just to clarify - the corner spheres provide the quality of the Firm ride. The system only goes Soft when the centre spheres are switched into circuit (by the electrovalves), by putting extra sphere (compressible gas) volume into the system. When they switch out (EVs go off), the ride immediately becomes Firm again.
But when the centre spheres switch out EVs go ON not off. When EVs go ON or the piston sticks to rust and stays ON , it will not be possible to lift and lower the car, because the LDS cannot flow through solenoid. When the piston sticks to rust and stays permanent off, the car will tilt too much in corners. Is this correct or I don't understand it correctly? Thanks for answer
User avatar
white exec
Moderating Team
Posts: 7384
Joined: 21 Dec 2015, 13:46
x 1445

Re: C5 hydractive 3 electrical issue

Post by white exec »

The centre spheres are isolated from the hydraulic system when there is no supply to the EVs (and monitoring LEDs will be off). When the EVs are powered up, the system goes to Soft (centre spheres now in hydraulic circuit) and the LEDs will illuminate.

Lots of detail about the Hydractive systems on citroen.tramontana.co.hu - go to Suspension > Hydractive 3.
Also covers Hydractive 3+, which is what you have.