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dimmed dashboard

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Old Sep 6th, 2020, 12:06   #1
v40Derek
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Default dimmed dashboard

Hello,

I tried searching this forum to see if a similar question had already been posted but found none - but I'm sure I'm not the only one who has had this problem.
My dashboard is randomly dimmed(during the day). The battery is almost new and has been checked already, the alternator also checked and working properly to power and charge everything in the car.
After a while, the dashboard returns to its normal "bright" mode.
My car is a V40 cross country D4 (2017)

I have tried to adjust contracts, change the theme but is still the same.
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Old Sep 6th, 2020, 13:12   #2
TonyM
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i think that this is normal - the brightness of the display changes when the ambient light level changes so it automatically adjusts for night time and daytime.


(edit)...on the other hand, re-reading your post - it shouldn't be doing this randomly maybe the sensor is faulty?

Last edited by TonyM; Sep 6th, 2020 at 13:27.
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Old Sep 6th, 2020, 15:38   #3
v40Derek
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definitely is not expected behaviour because when is dimmed I barely see anything there plus it was fine for the first few months since I've purchased this car.
I will try to take a photo and attache here for comparison.
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Old Sep 10th, 2020, 08:10   #4
v40Derek
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Picture taken today at 6:30am and the dashboard is barely visible compare to the normal state.
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File Type: jpeg WhatsApp Image 2020-09-10 at 06.32.45.jpeg (37.8 KB, 24 views)
File Type: jpg v40.jpg (176.2 KB, 20 views)

Last edited by v40Derek; Sep 10th, 2020 at 08:13.
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Old Sep 10th, 2020, 11:26   #5
piotrek
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Maybe you accidentally covered the ambient light sensor in the middle of dashboard (red alarm LED under the windscreen) - that sensor steers the dimming function.
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Old Oct 23rd, 2020, 00:00   #6
LeyburnSheep
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Quote:
Originally Posted by v40Derek View Post
Picture taken today at 6:30am and the dashboard is barely visible compare to the normal state.
Got what appears to be the same problem here. V40 T2 MY2015 50,000 miles. Most of the time the instrument panel is lit so that it is readable in normal daylight. Occasionally - maybe once every 8 to 10 journeys - the instrument panel lights go out completely for some 10 minutes or so, then come back on. All a bit random. Ambient light sensor in the centre of the dashboard, beneath the windscreen, is not covered.

Will research this and post anything further as a resolution is needed!

Cheers

Dave
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Old Oct 23rd, 2020, 18:24   #7
Vman40
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When the headlights come on/it's dark outside the display automatically dims - with the darker weather maybe that's causing it to be more noticeable.

There is a dimmer switch for the interior dash display lights to the left of the headlight switch - if you move it the brightness when dark/headlights are on changes.

In day mode the dimmer doesn't affect mine much, I only find it affects mine when dark or I go underneath lots of overhanging branches , or go in a tunnel.
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Old Oct 23rd, 2020, 18:58   #8
Boatie
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The rheostat on the V70 (P3) I used have was always a bit 'delicate' and needed careful positioning to get an appropriate setting. The one on my present 9 month old V90 looks identical. I know a variable rheostat may sound a bit old fashioned but it's worth considering.
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Old Oct 24th, 2020, 07:01   #9
Vman40
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Yes, it's not the best control - plus they have combined the light sensor adjustment and brightness control in the one adjustment.

If I have mine adjusted right for unlit road driving at night it's too dark for driving during the day in a tunnel.
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Old Oct 25th, 2020, 11:08   #10
LeyburnSheep
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Quote:
Originally Posted by LeyburnSheep View Post
Got what appears to be the same problem here. V40 T2 MY2015 50,000 miles. Most of the time the instrument panel is lit so that it is readable in normal daylight. Occasionally - maybe once every 8 to 10 journeys - the instrument panel lights go out completely for some 10 minutes or so, then come back on. All a bit random. Ambient light sensor in the centre of the dashboard, beneath the windscreen, is not covered.

Will research this and post anything further as a resolution is needed!

Cheers

Dave
I am hoping that the wisdom and guidance of the forum can help me through to a conclusion with this one. This is most definitely a system fault, not a configuration setting!

Vehicle
Volvo V40 T2, manual gearbox, 64 plate, MY2015 50,000 miles

Problem
The instrument lights occasionally appear to stop working completely - maybe just dimming to the minimum - so that the centre LCD display, fuel gauge bars on the left, and the ‘change gear’ indicator on the right, cannot be seen. The display is working – it’s the backlight that turns off. The display looks similar to a mobile phone screen when the backlight packs in – hold it to the light and you can see a faint image. The problem appears to be random, has happened a handful of times during the last 6 months, and can happen when travelling at a steady pace. The display lights have always come back on by the end of the journey. The rest of the dashboard lights, and the centre dashboard colour LCD , do not go off, and nothing else appears to be affected.

Initial Diagnostics
All appears to be working well when undertaking an activation of the instrument panel.

Reading Diagnostic Trouble Codes (DTCs) reveals the following:
See attached image 'DTC List.png'.

The following may be incidental! … The reverse lights had recently stopped working. On the morning of 17/10/2020, with the ignition off, I removed the reverse light bulbs to check those for continuity. I also removed fuse number 37 in the CEM (under the glovebox) – marked as ‘reverse lights’ in the owner’s manual – and checked for power using a multi-meter, getting +12V on the left terminal. Fuse was fine. I then found and repaired a broken wire on the reverse light switch. I snipped through the cables with the ignition off, to remove the plug for repair.

Interestingly, the last time the instrument panel lights stopped working (or suddenly dimmed to the minimum) was on a journey on 22/10/2020, so no DTC appears to have been reported for that (or any other?) occurrence.

With reference to the DTCs list– the interesting one is ECM-08AD00 No match. Any thoughts, please?

My first suspicion is the Sun Sensor, mounted in the centre of the top of the dashboard, the thinking being that if that sends an erroneous value, then the instrument panel lights could react accordingly.

The Central Electronic Module (CEM) parameters list 3 items – Twilight Sensor, voltage, Sun Sensor Left, Signal, and Sun Sensor Right, Signal.
See attached image 'CEM Items.png'.

When covering the Sun Sensor - that’s what the parts list calls it! …
See attached image 'Sunlight Sensor.png'.

... the Twilight sensor, voltage changes from 2.1V (uncovered – cloudy day) to around 5V when covered over. However, the Sun Sensor Left, Signal and Sun Sensor Right, Signal values don’t change.
See attached image 'Graphic Display.png'.

I wonder whether I am going down a rabbit hole with this, but the first question is what is called the Sun Sensor actually the thingy in the middle of the top of the dashboard? And why a left and a right Sun Sensor? Can anyone shed some light on this, please? … pun intended!

The next suspected culprit is the Driver Information Module (DIM) or CEM themselves. Any thoughts / experience, please?

Many thanks

Dave
Attached Images
File Type: png DTC List.png (102.8 KB, 10 views)
File Type: png CEM Items.png (23.8 KB, 10 views)
File Type: png Sunlight Sensor.png (32.8 KB, 10 views)
File Type: png Graphic Display.png (16.0 KB, 8 views)
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