Another n00b query this one about Xantia dash lights failing

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Re: Another n00b query this one about Xantia dash lights failing

Post by NeaU »

By Clogzz's feedback I understood that If the clock, sliders and dash are in the dark, it’s the rheostat. But what then if the threostat has no feed (power). I checked the rheostat wiring diagram and find out that white wire to the rheostat comes from fuse F19. As I understood the power should come from the battery to a MAXI fuse and then from there to the light switch in the steering column and then from there to the fuse F19 in the cabin fuse box. All fuses is checked and are OK including MAXI fuses. Am I right if I think the fault is in the light switch in the steering column and all the relays related are integrated to that switch?
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Xantia rheostat wiring.jpg
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Re: Another n00b query this one about Xantia dash lights failing

Post by white exec »

Hi NeaU,
Post your VIN, and I'll check the wiring diagram and post it here if it's different from the one above.
Chris
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Re: Another n00b query this one about Xantia dash lights failing

Post by NeaU »

Hi Chris,
I think the wiring diagram I attached is the right one, but here's my VIN: VF7**************[VIN obfuscated, can be read by forum staff]

As I wrote in my first reply the instrument panel background lights begun lit when turning ignition on regardless that the headlights were on or not (auto mode). I changed the whole instrument panel to a tested spare part (after the background lights were already gone) with no success. Now the system works the way the rheostat gets power from fuse F19 when the headlight or parking lights are on and gets not when the headlights are on auto mode (by the way the wire is yellow). I think this is how it should be so the fault was not in light switch as I thought. Now if I connect the rheostat the fuse burns immediately. So the fault must be in wire(s), short circuit somewhere, I don't know where. I think it's better to glue couple of leds next to gauges so I can see them when it's dark, than remove the whole f***ing dashboard to reach the wire/wiring.
Last edited by NeaU on 14 Jan 2020, 16:05, edited 2 times in total.
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Re: Another n00b query this one about Xantia dash lights failing

Post by GiveMeABreak »

Don't want to tread on your toes here Chris - but to save time, I have an electronic one of these with correct options for this model, which is a little different to the one the OP posted up: Certainly on the earths and some of the wiring codes...

Image

and here's the actual circuit:

Image

and lastly the locations... (Click image to magnify)
Xantia Circuit.PNG
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Re: Another n00b query this one about Xantia dash lights failing

Post by NeaU »

Hi GiveMeABreak,
and many thanks!
So I have to spend rest of my life mostly at my car's footwell, am I right?
Well, it doesn't any matter anymore, I'm coming crazy anyway!!
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Re: Another n00b query this one about Xantia dash lights failing

Post by white exec »

No problem, Marc. Have been out for the evening, so thanks for posting those pages.

Dash (instrument) lighting can come on when IGN is switched on (so instruments are readable without having to turn on side/headlights), or when side lights are turned on, depending on car and model.
Circuit diag should establish which is the case here.
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Re: Another n00b query this one about Xantia dash lights failing

Post by NeaU »

Thanks Chris!

The only difference in Marc's rheostat wiring diagram is that there's a relay between light switch and the fuse F19 and there's no cooling switch shown. The wire from fuse 19 is marked as white in both Marc's and mine (Haynes) diagrams.
I disconnected the rheostat and checked if there was any voltage in those two wires when turned lights on. And there was voltage in the yellow one. I checked the thing again by taking off the fuse F19 and there wasn't any voltage in it so the yellow one is feed from the fuse.
But who's care, f**k the colors. So I thought the white wire must lead to the dashboard backlights, smart thought, wasn't it?
There's only one problem in this whole thing. If I connect the f***ing rheostat between those two wires (the yellow and the white) then the fuse F19 will be die immediately! Now, let's see the rheostat, resistance varies between 0.4 and 12.6 when turning the rheostat wheel and multimeter is set to 200 ohms so I think it's fine. The fault must be somewhere else, but where is a good question, isn't it? I've already tested with another, tested instrument cluster with no success.
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Re: Another n00b query this one about Xantia dash lights failing

Post by white exec »

Suggests a short circuit downstream of the rheostat.
Maybe a bulb filament that has blown shorted, although that is unusual.
You'll have to probe towards the instrument lights and see what's going on.

Maybe be a messy mod by someone? Most likely candidate for this would be the radio, which takes a "lights on" feed in order to dim its display.
Chris
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Re: Another n00b query this one about Xantia dash lights failing

Post by xantia_v6 »

This appears to be another car with scandinavian DRL headlights, so the wiring will not exactly match any of the RHD diagrams. The car in this post had the same symptoms: viewtopic.php?t=64187

I don't think that we have enough information to pinpoint the issue, but it would help if you could determine whether one of the DRL relays operate when the side lights are switched on. This should make the headlights turn off.
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Re: Another n00b query this one about Xantia dash lights failing

Post by GiveMeABreak »

The diagram I put was for LHD (and is shown on diagram 3 that I posted earlier) in case it's relevant.
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Re: Another n00b query this one about Xantia dash lights failing

Post by NeaU »

Hi again!

All the lights works like they should except the dash backlights. Well, I don't really know. Maybe I should use a heavy hammer to see what is going on behind the dashboard. #-o

Thanks a lot anyway!
Last edited by NeaU on 15 Jan 2020, 13:01, edited 1 time in total.
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Re: Another n00b query this one about Xantia dash lights failing

Post by white exec »

Worth looking at that post Mike links to above viewtopic.php?p=629768#p629768,
but irrespective of the arrangement for headlights/DRLs/Scandi variations, my guess is that the dash/instrument illumination lights (the dimmable ones, fed of the rheostat) should be a simple matter. If connecting them to a supply causes the fuse to blow, there really does suggest a short downstream.
Can't imagine that anything else would be fed off the rheostat except the relevant dash illumination.

Looks like a a case for having to explore behind the dash, but I'd be starting with the radio first, especially if it's non-original.

Use a multimeter on ohms on the cable leading away from the rheostat (and supplying the bulbs), and pull each bulb (I know a fiddly job) until the short to Gnd disappears.
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Re: Another n00b query this one about Xantia dash lights failing

Post by NeaU »

HOORAY!

I got the dash backlights back, I checked each blub as Chris recommended.
Thanks everyone for help, especialy to Chris for the advice wich solved the problem and to Marc for those diagrams.
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Re: Another n00b query this one about Xantia dash lights failing

Post by Stickyfinger »

and ?.....what was the problem ?
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Re: Another n00b query this one about Xantia dash lights failing

Post by NeaU »

This was the problem: '... a bulb filament had blown shorted, although that's very unusual'.
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