Citroen XM Forum

On second thought, there is no sidelight bulb, either. Headlights and main beam, at least that's what I have on mine. I seem to recall there is a symbol but no room for any bulb, it's covered from behind.

But of course, it might be different if you have that dim-dip or whatever circuit in the UK, I never really understood that.

Anyway, whatever it is, it's not the internal lights. As a rule, you don't need a telltale for something directly visible to the driver.

Your right about that 'bulb' symbol sorry... My mistake. Other than that description is sound!

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edelweiss wrote:Yes, overhead light dims but never goes out. I have to disconnect the battery each night.
Overhead light will only switch on via dash switch when the ignition is in ' off' position or key is out. When engine is running or ignition halfway turned, the overhead interior light won't switch on, either from dash switch, or when I open the doors

I'd suggest to concentrate on these first, and we'll see whether it has any bearing on the other problems.

There are a few interior lights that are not dimmed, namely the glovebox and the ceiling lamp map lights. These are fed from fuse F5. Can we know whether these work all right? The same circuit feeds the dimmer, actually.

The rest of the lights can be divided into two groups but both groups receive their feeed equally from fuse F27, via the long timer: dimmed interiors (ceiling, above doors) and non-dimmed ones (courtesy lights in the door bottoms, boot lights). Do check that the second group works all right but let's go on under the assumption now that they do.

The dimming lights are all dimmed from the ground: the timer unit grounds them. Even if you just switch them on using the dashboard switch, this happens by the time unit earthing them completely. So, as a first step, you could disconnent this unit and check what happens. The blue box has a 7-pin brown connector and can be found under the glovebox on an LHD car; I'm not sure where it exactly is on RHD.

djg wrote:

edelweiss wrote:Yes, overhead light dims but never goes out. I have to disconnect the battery each night.
Overhead light will only switch on via dash switch when the ignition is in ' off' position or key is out. When engine is running or ignition halfway turned, the overhead interior light won't switch on, either from dash switch, or when I open the doors

I'd suggest to concentrate on these first, and we'll see whether it has any bearing on the other problems.

There are a few interior lights that are not dimmed, namely the glovebox and the ceiling lamp map lights. These are fed from fuse F5. Can we know whether these work all right? The same circuit feeds the dimmer, actually.

The rest of the lights can be divided into two groups but both groups receive their feeed equally from fuse F27, via the long timer: dimmed interiors (ceiling, above doors) and non-dimmed ones (courtesy lights in the door bottoms, boot lights). Do check that the second group works all right but let's go on under the assumption now that they do.

The dimming lights are all dimmed from the ground: the timer unit grounds them. Even if you just switch them on using the dashboard switch, this happens by the time unit earthing them completely. So, as a first step, you could disconnent this unit and check what happens. The blue box has a 7-pin brown connector and can be found under the glovebox on an LHD car; I'm not sure where it exactly is on RHD.

Ok.

So the fuse 27 set of lights you outline above seem to have got caught up in this fiasco

-dimmed interiors above back door: the smaller light in that panel will not such off completely (only dim) when ignition is switched off....the larger light in the panel kicks in when ignition is 'off', that is if I have opened the door in the intervening period, after which the light won't turn itself off at all...

-if I switch that rear passenger light on (IE via the switch above the rear passenger door), then the light will switch on only when the ignition is on.

door bottom lights work when ignition on or off

Fuse 5 set:
Ignition turned to off:
-glovebox light is dim.
-interior map lights don't work via switch

Ignition turned 'on':
-glovebox light and map light works as it should

After turning ignition off, the digital dashboard display (I.e the one directly behind the steering wheel) lights up a bit as soon as the timer kicks in to try and shut everything down... After which point I've got a dimly lit car, like it or not, until I disconnect the battery


If u think it's any use I'll get behind the glove box tomorrow and see if I can find that blue box.

Are you LHD or RHD? If RHD let's wait until John or Chris can confirm where the timer is.

Wait a second. My money was on that timer half an hour ago but now, with the glovebox also dimming, as you mentioned, also considering that the radio is also playing up (also fed from F5), I changed my mind slightly. It will be more likely somewhere in the feed line of F5. That comes from the ignition switch, goes through the fuse and hits the 848 engine running relay (situated in the main board, 2nd relay of 2nd row). That relay is resposible for telling some subsystems (like A/C) that they are allowed to operate.

So, at first I'd remove and re-seat that relay. If you happen to have a known good replacement, it's easy to test, although I wouldn't actually suspect the relay itself. As a next step, if you have a multimeter, it would be very interesting to see what voltage you get on the fuse F5. If anything but normal board voltage, try to locate and remove that timer relay momentarily and repeat the measurement (and also check whether the non-dimmed lights resume their normal operation).

https://youtu.be/-g2GTMxFIyM" onclick="window.open(this.href);return false;

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I saw the video in the meantime. It also shows that you're RHD.

Either some foul play with the F5-848 feed or the timer relay, much more likely that not.

So from my understanding, that relay you refer to is in the main fusebox in the passenger footwell?

If so, I changed out the whole fusebox already with a known working one, all relays included...

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This is great, a lesson in auto electrics! Will get onto this and let u know results... Thanks¡

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It is asking for problems to swap out XM electrical assemblies (such as the main fuseboard), unless it is absolutely certain that the assembly and all its components are exactly the same version/type number. Many components which look externally identical are wired/configured differently to cope with different models and equipment levels, and with design changes over time. There is also the risk of disrupting otherwise working circuitry.

The XM is not the car to tinker with in the hope of developing auto-electrical skills. Due to its complexity, the car presents a challenge even to many experienced vehicle electricians. For practice purposes, better to work on something much more simple.