CITROEN XM Internet Reference page 97

68 Hydractive 1 and Hydractive 2 explained Suspension
The difference compared with the Hydractive I system is very obviously much improved giving the
vehicle a much more comfortable ride over a much wider range of manoeuvres and speeds than was
allowed previously, and with no corresponding increase in body roll. The operating principles and
sensors are as per Hydractive 1, the only change being the fitment of a one-piece steering wheel
sensor, which has been in use since RP no. 5852. The markings on the suspension switch in the cabin
now reads 'Normal' and 'Sport', with the dot-matrix message likewise modified.
With the introduction of the 'New XM' with its many, many improvements internally and externally, came
the addition of the anti-sink suspension system. This incorporates a specific antisink valve, which acts
as a lock within the suspension hydraulic system, with an extra 500cc accumulator sphere housed on
the rear axle to 'back-up' the system, thus preventing the vehicle from sinking down on its stops for a
much longer period of time. It does not affect or interfere with the Hydractive part of the system.
The electronic speed sensor, which previously fed information to the Hydractive ECU now shares the
information to drive the electronic speedometer now fitted, with the sensor itself modified in that it no
longer drives a speedo cable.
There are slight modifications to the latest Hydractive ECUs, mainly with regard to different parameters
to cover extra weight or torque features m some models, e.g. the 25TD models, but the operating
principles and features remain the same to date.
(Thanks to Andy Burnett and the CCC)
Citroen XM Internet Reference Version 1.0 97
3/3/99