Citroen XM Forum

Found it!!!

Had another play with the intermittent lights today. Just to make sure before swapping the blue box over. I swapped over the centre lights for the original. No difference. So that is eliminated. Then fuses again. I took out the Hydractive fuse F19 and popped it back in, lights came on and a clunk of the electrovalve. Then lights worked as normal. Locked it up and went in doors. Came back out later on and unlocked it, nothing. No lights. So this time Fuse F27 was checked... Taken out and put back in..that's the light timers. Now works. Checked Fuse F34 too, which is hydractive and central locking. All fine. I did replace two of them to make sure. So I will check it all again later. But what I don't get is the electrovalve not appearing to clunk, or go into soft mode when a door is opened. You can hear a buzz...albeit faint, but it doesn't clunk off when the door is shut or locked. It's almost like the car isn't shutting off properly and when it does, it needs the ignition to power the lights again. Most confusing this.

I have the blue box of tricks for the lights, so will swap that over and see it if works. Can a defective blue timer effect the electrovlave?
It might of course be a door switch..... The drivers door does make a strange noise when it's locked.

Well after an hour, I went out to see if the lights would light up, and nothing, until I turned on the ignition all working again. Turned it off. Then closed the door, after usual 30 secs clunk from the valve. Lights then work with ignition off. You can open and close any door and all is fine, but the electrovalve is not buzzing and clunking with ignition off. Bit perplexed...

Changing the blue box tomorrow. Be amazed if it is that though....

There are two timers: a short one and a long one. The fading of the interior lights belongs to the first one. Also, this is the timer the central locking is connected to. If you don't have the proper response after unlocking, check these first (start with contact problems).

The long one works for both lighting and suspension. It's responsible for switching the door courtesy and boot lights off after 10 minutes of being open, as well as the suspension response after having left the car to stand.

So are the two timers controlled by the blue box of tricks under the dash?
The lights fade out as usual and behave fine, but only after the ignition has been on. It's the initial activation of the lights when unlocked and any door opened, they don't light up. Odd.

No. The short one is #961 on the diagram, the long one #837.

Swapping the blue box has not worked. But now I know about relay 837 I need to check that... If it exists on a mk1!

I wonder about the door switch being faulty, so either keeping the lights on or off.

Very possibly Will. But would one switch effect all the lights? I suppose it might. If a switch has gone, I have a feeling it could be the drivers door.

Sounds deep Russ, but once you crack it we will all know of a fix for ours if we befall the same issue