Hydractive ECU

Toby_HDi · Post by **Toby_HDi** » 16 Feb 2010, 00:25

The diode mod has been done.

On the white plug of the suspension ECU, there are three grey wires and one of the thick green wires. Obviously being diodes they need to be the correct way round.

About halfway down this thread there is a nice clear picture...

http://www.frenchcarforum.co.uk/forum/v ... alve+diode

Stempy · Post by **Stempy** » 16 Feb 2010, 08:31

A neater way is to fit the diodes inside the ECU, especially if you have it apart anyway.

Post by **CitroJim** » 16 Feb 2010, 09:51

Stempy wrote:A neater way is to fit the diodes inside the ECU, especially if you have it apart anyway.

Now, that's a good idea Stempy

Toby, I'd not personally use a glue gun on the ECU box. You might never be able to get it apart again

Electronics grade silicone is fine. I used Dow Corning 732 for both my hydractive and autobox ECUs and we use it at work in a very demanding role...

Toby_HDi · Post by **Toby_HDi** » 16 Feb 2010, 10:15

Now that is a good idea - I presume that you would solder them to the legs of the appropriate connector pins?

Jim, the glue gun comment was aimed at securing the VN05Ns to the board, not to glue the ECU box together. For that I've used some Loctite black silicone.

As I say, I may tidy it up at some point. For now though, I'll leave it as it works.

Stempy · Post by **Stempy** » 16 Feb 2010, 11:50

Toby_HDi wrote:Now that is a good idea - I presume that you would solder them to the legs of the appropriate connector pins?

Yes, that's just what I did to mine.

davewithington · Post by **davewithington** » 17 Feb 2010, 21:26

Undulge me gents. Where can I find my suspension ECU?

Toby_HDi · Post by **Toby_HDi** » 17 Feb 2010, 21:30

Under the black lid, front left corner of engine bay next to the coolant expansion tank. There lives the suspension ECU alongside the engine ECU.

citroenxm · Post by **citroenxm** » 17 Feb 2010, 22:17

1993 Xant will ONLY have a Suspension ECU, as these early girls are completely mechanical!!

Paul

Toby_HDi · Post by **Toby_HDi** » 17 Feb 2010, 22:20

citroenxm wrote:1993 Xant will ONLY have a Suspension ECU, as these early girls are completely mechanical!!

Paul

Quite true Paul, is the suspension ECU still in the same place?

citroenxm · Post by **citroenxm** » 17 Feb 2010, 22:24

Yes Toby, it is, the only place they had space to put them

Paul

davetherave · Post by **davetherave** » 16 Mar 2010, 16:42

Just taken my ECU apart on the XM try and find why the suspension is like concrete.
It seems that although the vno5n's are not as bad as tobys, it is clear that they have taken some heat, at some point, more marked on one than the other.

Does maplins do these? i cant find them on the website, I will also try and solder in the diodes at the same time!!

Hopefully this wil help the ride become bearable!
Dave

Ps is running the car without its hydractive ECU ok?
The ride really doesnt feel that different!

Post by **CitroJim** » 16 Mar 2010, 18:41

Dave,

Hold on a bit. before worrying about replacing the VN05Ns, do some checks first.

Can you hear the electrovalves humming with a door open and engine off (Hydractive in soft mode).

Do they hum for 30s when the door is shut and then switch off with a satisfying click?

When you open a door, can you hear them click, then hum for a split second and go quiet? If you do, you need to do the diode mod.

Another test you can do is with a voltmeter. Check the voltage going to each electrovalve. When a door is opened, you should see an instantaneous reading of perhaps 9V, dropping to 3V when the valves are humming. An old-fashioned analogue voltmeter is best for this as you can see the needle give a good kick at the start and then falling back to about 3V

Yes, perfectly safe to run with the ECU disconnected, it just leaves the suspension in hard mode and if you notice no difference, there is a clear problem.

Farnellsell VN05Ns.

davetherave · Post by **davetherave** » 16 Mar 2010, 18:51

Cheers Jim just need to find the electrovalves !
Ill have a go tomorow, ive just been out without the ECU and it perhaps feels a bit more bouncy.
Ill have a listen to the electrovalves this evening.
Whilst i have the ecu apart ill do the internal diode mod!
Dave

Post by **CitroJim** » 16 Mar 2010, 18:58

davetherave wrote: Whilst i have the ecu apart ill do the internal diode mod!
Dave

Good idea Dave

The electrovalves are on the Hydractive Centre Sphere blocks. You will see a two-pole brown electrical connector on each valve and from the top of each valve you'll see a leakage return pipe about 6mm in diameter.

They usually hum loudly enough to be heard just by kneeling down by the front/rear, looking up at the subframe and listening. The start and end clicks are normally very audible.

You have replaced the centre hydractive spheres? If these are totally flat or ruptured, you'll get the same symptoms - very hard and bouncy suspension.

davetherave · Post by **davetherave** » 16 Mar 2010, 19:21

I've replaced the rear one, but have yet to replace the front centre hydractive.
It does make a loud clunk when i walk away from it, as well as a hissing noise from the front

Ill put the stands under it and measure voltage tomorow, i hope it is just the front hydractive sphere as i believe that may be original

.
Dave