Persistent ABS OUT OF USE display

We've all seen this readout once or twice in the life of our XM. Rectifying the problem is not always simple although possible. Here we deal with another side of the issue: the display itself. While the ABS is actually out of use for any reason, this warning is very intrusive on the dot matrix display, practically preempting it and masking most other information messages like open doors, radio stations and similar.

Electrical part list

The XM has a couple of billion electrical parts. It's not always easy to find where a specific item is located.

The factory manual and the circuit diagrams denote every part with a reference number. The listing below uses these numbers. Left and right, as usual, refers to the driving position.

Non-obvious parts in the XM

53 Water temperature control unit - LHD: Remove the glovebox. The unit is housed in a black Bitron box attached to the firewall side of the opening. RHD: The unit is located above the accelerator pedal.

Brake valve

Although there is a so-called repair kit for the brake valve, this only contains replacement rubber seals. These seal the valve to the outside but they have nothing to do with the functioning of the valve itself; the sealing of the working elements rely on the very close tolerance between those parts. Once the pistons inside the valve or the cylinder they travel in wear out, the valve starts leaking (this means leakage into its return lines and not to the outside world).

On the XM

Before you disconnect the battery on a Hydractive I XM, never forget to wait for the system to release the pressure. If you fail to observe this, serious damage can occur the next time the system is started.

How to connect wires

When you retrofit items not originally fitted to your car, you often have to tap into wires or make new connections not already present in the electrical circuitry. The best way to do that is by soldering. Although making nice soldered joints requires a little bit of training and experience, it's still far from rocket science. Practice here doesn't mean months or years, much more like five minutes, especially as we're not speaking about soldering delicate semiconductor components on multilayer printed circuit boards but a couple of thick wires...

Cleaning tires

Avoid silicone based products, they are rather harmful, although it might seem different at first sight.

The long hydrocarbon chains that make up the rubber of the tires are attacked by both ultraviolet rays and ozone. As the molecules break up, the rubber loses its elasticity. The manufacturers use carbon black to protect the rubber against UV rays (this is why we only have black tires). A wax based protector is also used: as the tire rolls on the road, additional wax is forced to the surface and absorbes the harmful effects of ozone.

Spheres and comfort

With all those various spheres and damper diameter holes, for any given Citroën model or even accross models, it is difficult to see at first how and why all these physical factors influence the suspension comfort.