Citroen XM Forum

It might be help to list Citroens designations for systems and ECU's

Citroen do not list a H1 suspension system.
They did use a H2 ECU but this was not used on and is incompatible with the HYDRACTIVE 11 system.

The systems were:

HYDRACTIVE which came in early (1989) and late (1990 - 1993) versions.

HYDRACTIVE 11 fitted from 1993 onwards.

The ECU's were:

Marked HYDRACTIVE - for early HYDRACTIVE systems - green and white plugs on ECU.
(Note that the same ECU plugs were used on ACTIVA ECU's but there is no electrical compatibility).

Marked HYDRACTIVE H2, HYDRACTIVE H2B or HYDRACTIVE H3 - for late HYDRACTIVE systems - black and white plugs on ECU.

Marked H4 xxxxx or H5 xxxxx - for HYDRACTIVE 11 systems - black and white plugs on ECU.
(Note that these are the same ECU plugs as used on the H2, H2B, H3 ECU's but there is no electrical compatibility).
The xxxxx code on H4 ECU's determines the soft/hard settings which can be car and model specific.
The H5 ECU's are once only codable to set the soft/hard settings.
These H5 ECU's must be read on a LEXIA to determine the car/model they are set for.

John

russ92xmsed wrote: From what I understand, is H1 is essentially a cruder system, by that I mean it is that little bit slower to react to cornering speed. And with each development it got quicker and quicker. But with H2 the difference is even when put in sport, it is still in soft but pops into sport more often....right or wrong?

Absolutely right Russ. Sport mode just changes the thresholds at which switching takes place. It's more eager to come in during sport mode.

Driving an H2 machine stuck in soft is like trying to hustle a duvet around a corner...

xmexclusive wrote:It might be help to list Citroens designations for systems and ECU's

Citroen do not list a H1 suspension system.
They did use a H2 ECU but this was not used on and is incompatible with the HYDRACTIVE 11 system.

The systems were:

HYDRACTIVE which came in early (1989) and late (1990 - 1993) versions.

HYDRACTIVE 11 fitted from 1993 onwards.

The ECU's were:

Marked HYDRACTIVE - for early HYDRACTIVE systems - green and white plugs on ECU.
(Note that the same ECU plugs were used on ACTIVA ECU's but there is no electrical compatibility).

Marked HYDRACTIVE H2, HYDRACTIVE H2B or HYDRACTIVE H3 - for late HYDRACTIVE systems - black and white plugs on ECU.

Marked H4 xxxxx or H5 xxxxx - for HYDRACTIVE 11 systems - black and white plugs on ECU.
(Note that these are the same ECU plugs as used on the H2, H2B, H3 ECU's but there is no electrical compatibility).
The xxxxx code on H4 ECU's determines the soft/hard settings which can be car and model specific.
The H5 ECU's are once only codable to set the soft/hard settings.
These H5 ECU's must be read on a LEXIA to determine the car/model they are set for.

John

Sorry John I was being lazy and referring to the S1 cars as having H1 and then S2 as H2. So it was simply known as Hydractive initially.

CitroJim wrote:

russ92xmsed wrote: From what I understand, is H1 is essentially a cruder system, by that I mean it is that little bit slower to react to cornering speed. And with each development it got quicker and quicker. But with H2 the difference is even when put in sport, it is still in soft but pops into sport more often....right or wrong?

Absolutely right Russ. Sport mode just changes the thresholds at which switching takes place. It's more eager to come in during sport mode.

Driving an H2 machine stuck in soft is like trying to hustle a duvet around a corner...

Aha! I'm learning, I did know that honest ....Really so a mk2 then behaves quite differently when stuck in soft it appears. It would be very interesting driving a mk1 stuck in soft mode and then a mk2 stuck in soft back to back just to see how they differ. Then drive them properly working. to MIRA!!!

Back to my glow plug light....it worked tonight! First time in a very very long time.....so got to be an earth issue must be.

This is more for Jim!! Not as much space as I remember. But hopefully it is enough....

On a 2.1TD you have to access the hydraulic pipes on the regulator from underneath.

Excellent Will I was worried if the regulator was functionally inaccessible as it was on my old TCT Auto...

That looks a lot more open and accessible...

When Plaides replaced my regulator Martin did it from underneath when on the car lift.

Norman

Excellent! There is more room underneath... but I was taking a pic with the iPad, whilst doing fluid checks....it has no flash, so hence the above shot...albeit useless.

The wind got up the old SED's tail pipe yesterday night. Cos It's got an intermittent rear brake light now... Will see if it has fixed it self in a mo....