Dashboard lights dim sometimes, sometimes not

[Mahlon]

2001 XC70

Please bear with me here because I don't know all of the lingo for talking about this car. But I'm having a problem with the dashboard lights. The dashboard lights (including radio display) are sometimes dimmed. And then sometimes they are lit correctly. It seems random. This is with the headlight switch in any of the three positions. When dimmed, the little green LED by the headlight switch is off (this is when the switch is in the 'on' position). This is in both day or night driving.

When the lights are dimmed, the hi beam (turn signal lever) will engage when the lever is pulled towards the driver, but will only maintain hi beams while that position is held manually. If I let go, the lever goes back to the neutral, as it shoud, but the high beams also cut and low beams are engaged. In other words, there's no way to retain the hi beams.

So.... I did some looking around have seen a lot about bad DIMs. But since haven't had any of the other symptoms of a bad DIM (flickering, fuel guage erratic, messed up information), I was wondering if anyone had some ideas of what might cause my problem? Hopefully something else. Or does it look like a bad DIM anyway? That's expensive, I've heard.

So, anyone have an idea why dash lights might be dimmed randomly?

Thanks for the help in advance,

Mahlon

[MacNoob]

Sounds more like a bad headlight switch to me.

[Quartz]

First off, you need to eliminate a few variables here:

- There are few different options in the computer for how the headlights/DRLs behave. In my car for example both the horizontal 'O' and vertical positions turn the headlights on (but not the 45-degrees position), so you need to clarify what you mean by "'on' position". Also, in a lot of cases the computer is set in such a way that the highbeams are 'disabled' (only work if you hold the lever back) if the headlight switch is in the horizontal 'O' position. This is how my car is currently set. Before doing anything else, put the switch in the vertical position and check to see if they'll stay on or not.

- The green LED by the switch brightens and dims with the rest of the lights, and if it's starting to fade (contrary to popular belief LEDs do fade) it might be so dim it's hard to see. Try adjusting your dash lights all the way up and cupping your hands around the LED and check to see if it's really going completely off or not.

- As for the random dimming issue, first make sure you don't have crap in/on your car that might be covering the light sensor. In my '07 XC70, the sensor is built into a bump on the dashboard, front and center at the base of the windshield between the blower vents (I'm not completely familiar with '01's and if yours is somewhere else). Once you know where it is, make sure you don't have stuff possibly covering it that slides around when you drive, causing the problem.

[JRL]

ON is 12:00 and your high beams work
OFF is 9:00 and the high beams don't work (stay on)
A very stupid Volvo design and your car sounds normal to me

[Mahlon]

First off, you need to eliminate a few variables here:

- There are few different options in the computer for how the headlights/DRLs behave. In my car for example both the horizontal 'O' and vertical positions turn the headlights on (but not the 45-degrees position), so you need to clarify what you mean by "'on' position". Also, in a lot of cases the computer is set in such a way that the highbeams are 'disabled' (only work if you hold the lever back) if the headlight switch is in the horizontal 'O' position. This is how my car is currently set. Before doing anything else, put the switch in the vertical position and check to see if they'll stay on or not.

- The green LED by the switch brightens and dims with the rest of the lights, and if it's starting to fade (contrary to popular belief LEDs do fade) it might be so dim it's hard to see. Try adjusting your dash lights all the way up and cupping your hands around the LED and check to see if it's really going completely off or not.

- As for the random dimming issue, first make sure you don't have crap in/on your car that might be covering the light sensor. In my '07 XC70, the sensor is built into a bump on the dashboard, front and center at the base of the windshield between the blower vents (I'm not completely familiar with '01's and if yours is somewhere else). Once you know where it is, make sure you don't have stuff possibly covering it that slides around when you drive, causing the problem.

First off, thanks for the help. Yes, my 2001 is like yours. "ON" is the vertical position. This is the position I'm talking about when I say the hi beams won't stay on.
I believe that he LED is completely off (at least, as far as I can tell) when dashboard lights dim and the hi beam doesn't work. Also, while the lights are dimmed/malfunctioning the adjustor for the dash lights doesn't work either.

I haven't checked the light sensor yet, but I don't think that it's covered. When the lights are not dimmed and working properly, the lights also dim properly in from day to night.

Again, thanks for your help. Any other ideas?

Mahlon

[Quartz]

Ok, just to be clear: when the switch is in the vertical position, the highbeams will stay on when the dash is 'bright', but won't stay on when the dash is 'dim'?

That's obviously not normal behavior. I don't know enough about the specific electronic setup in XC70's to make a definitive call on this one, but if it's at all similar to the work I do with computer and networking gear, it sounds like a power problem. I'd guess one of the computer modules might be shorting out or there's an issue with the wiring harness or something. The best thing to do at this point is probably bring it to a shop/dealer and have them read out any diagnostic codes, just so you know where you stand. I've gone through a couple rounds of mice and squirrels in my car that have caused weird issues, so another thing you could do is pop the hood and look around, as well as get under the car and see if you see anything obvious.

[Quartz]

Another possibility is that the computer is just messed up and doing erratic and inconsistent things re: headlight switch position and daylight sensor.... although you say that the dash brightness control stops working too, but I wouldn't expect that to be a 'soft' switch that goes through canbus. Again though, I'm no expert on XC70 wiring, so maybe someone else has better info.

[Quartz]

ON is 12:00 and your high beams work
OFF is 9:00 and the high beams don't work (stay on)
A very stupid Volvo design

I think the switch was probably a fine idea initially: it's logical that in the 'off' position you'd be able to flash the highbeams to get someone's attention but wouldn't be able to keep them on. But when they added the auto-on headlight feature and the whole DRL stuff then it didn't make sense anymore.

[Mahlon]

Ok, just to be clear: when the switch is in the vertical position, the highbeams will stay on when the dash is 'bright', but won't stay on when the dash is 'dim'?

Correct. And when I say the dash lights are dim, I mean they are DIM, not the normal dim when the sensor switches back and forth from day to night.

I'll probably take it to the mechanic. He's been servicing the car for a few years.

Thanks!
Mahlon

[Quartz]

Correct. And when I say the dash lights are dim, I mean they are DIM, not the normal dim when the sensor switches back and forth from day to night.
Yeah, that really sounds to me like a power issue of some kind.



I'll probably take it to the mechanic.
Well, either way none of what you're seeing is normal, so something's obviously wrong somewhere and it's unlikely to fix itself. I'd be leery of just ignoring it- it might get worse and the last thing you want is your entire electrical system dying while you're flying down the highway some night.

[billr99]

One of the first signs of the DIM going out. Leave it go for now as other things will occur before the DIM goes permanently.

Good luck,

Bill

[Ricka]

Hello.I was wondering if you ever got this problem fixed?I have a 2003 XC70 with very similar issues.Certain dash lights(message center,odometer,climate control) are so dim during the day you can't see them.At night they are visible but dim.High beams won't stay on(12 O'clock position)and dimmer switch doesn't work.The radio display is not visible at all.There seems to be many sensors in Volvos and the owners manual doesn't tell you where they are.Does anyone know where the light sensor is on my car?

[Lacy]

One of the first signs of the DIM going out. Leave it go for now as other things will occur before the DIM goes permanently.

Good luck,

Bill

I am also having this issue with a 2015XC60. Could you explain let it go because other things will occur before it goes out permanently? I've already had a bad fuel sensor replaced so another thing going wrong does not make me very happy.

[billr99]

I am also having this issue with a 2015XC60. Could you explain let it go because other things will occur before it goes out permanently? I've already had a bad fuel sensor replaced so another thing going wrong does not make me very happy.

A different setup on the 2015, I would hope, so I really can't say. On the old ones, once things started to go wrong due to cold contacts between the CPU and mainboard, either the faults would get progressively more frequent or that function would just fail all together as corrosion increased on the bad contacts. Re-heating, as some have suggested, would reflow the solder making the contacts functional again.

Now on a new 2015 board similar faults could arise, I suppose, as that is always a possibility with solder-on components. You would have thought that Volvo would have recognized the cause way back when and made changes to their manufacturing of the board to ensure that it would not repeat. But who knows. I would suggest that you go to the XC60 forum and see what the current wisdom, if any, is out there on 2015 specifics. Could very well be a totally separate issue such as bad chips, inadequate shielding, stray cosmic rays.

Good Luck,

Bill

[stones]

Hi I have a related question. Many of Volvo's design ideas really annoy me these days. God how I miss my old 940, and its reliability too I might add.

I have a 2006 XC90 D5 SE. The stereo light dims and brightens as I am driving, I live near quite a few tree lined roads so a bright sunny day can go dark suddenly, then bright again. I am sick of the stereo catching my eye (so much for SAFETY SAFETY SAFETY Volvo!) and distracting me while driving. Is it possible to turn this effect off with diagnostics as my car is in the garage in a few days?

Similarly, I wish I could turn off the seat belt warning alarm (yeah, yawn, safety safety etc, but who owns the damn car anyway?! ME!) I happen to use my "X" vehicle in 4x4 quite a bit when I go shooting on farmer's fields. Seat belts are not practical nor needed in such cases, but the alarm scares off any rabbits and is damn annoying. I was told this can't be turned off (by my garage) but I thought I would ask here in case some more knowledgeable people have any idea?

Finally, same goes for DRL. And yes same issue is for using vehicle off road doing a bit of vermin control shooting. It sort of ruins the game if I drive into a field lit up like a Xmas tree. Cant I CHOOSE to have my damn headlights OFF when my engine is running on MY car?!! If i sound angry, that's because I am! But not at you guys, just a bit sick of being nannied by my car, I want to use it how I want to use it, whatever happened to "have it your way"?! :D

thanks for any tips guys