Jose Gavilaīs CitroŽn XM Pages - Electrical System
XM is a complex car. It sports (depending model) Hydractive suspension, ABS, electronic engine management, electrical 'all' (from windows to central arm rest), lots of light bulbs (every control or button has its own light) and so on. XM design predates multiplexed systems (except very few of the latest units) so every electrical gadget should have a full set of wires going to it; there is not a common bus for power or data, as in multiplexed systems. A typical XM has some thousand meters of wire and lots of connectors which are one of the weakest points of these cars (read next paragraph).
Dealing with car electrical systems is not easy as one thing is the theorical schematic and then there is the real thing, as wiring is routed as it can be done. Fortunately there is plenty of information both for the schematics and the wiring loom locations.
This is one thing you will for sure care if you ever get an XM. First years models (1989-1991) were the worst and, probably, made up for the poor XM reputation, which lasted until production ceased in 2000. Some genius at CitroŽn decided to use multiple unprotected fast-on connectors as ground points. This is fine for laboratory use but, in real life, contacts get corroded and, in a car with several small computers and other electronic gadgets here and there, that proved to be a fatal error. About mid 1991 they switched to the classic ground points design and that improved things a lot. My XM was made in September 1992 so it had already the new design.
But this is just one weak point; almost every connector in an XM (and it sure has some dozens of them) can develop faults. As a sample, in the picture you can see a round door connector. It can't be clearly seen but blades had some oxide which caused, in my car, that central locking thought the door was not locked and also that electric window was unoperative. Some careful cleaning fixed it (by now!). This is another feature of XM electrical faults: they seem to go... but sometimes come back as soon as you need the car.
It is also very common to get an 'ABS fault' error which, sometimes, clears itself after some driving. Other times, though, it renders the system inoperative. Well...
These pages are UNDER CONSTRUCTION. More to come soon!
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