M4400 ALS not functioning at all under Windows 7 (but other backlight control works fine)

Hi all,

I originally posted this in the M4400 owners lounge but I feel it might be better off in its own thread.

Has anyone had an issue where the ALS suddenly stops working under Windows 7? I've checked BIOS settings, tried seemingly every combination of driver uninstalls/reinstalls, confirmed that both the Dell and Microsoft ambient light sensor services are enabled and running (and tried disabling, one, the other, and both) and have not had any luck. Unlike some other posts I found on here with the same-body Lattitude models, I can control the backlight manually with both the keyboard and software - it is only the ambient sensor that does not work.

Any advice? I am running BIOS A15, and Windows 7 x64 RTM.

Please let me know if any other information is pertinent.

 

I had the same problem where it just stopped working one day. It was a hardware issue and I was sent a replacement front LCD panel which fixed it. There were two wires for the ribbon to the sensor that were broken off.

 

I think that that if the ambient light sensor is on, then the dimming function of Windows 7 is disabled and vice versa.

 

Well, I chatted with Dell support last night and the rep said I seemed to have covered all the bases to rule out software issues, but he couldn't do anything to get me hardware until I restored the computer to its factory state (I/E, putting back on XP).

Its a simple enough process to image my current setup... But still, I would have thought that Dell, since they are offering a free upgrade to 7 for this laptop, would be able to handle support calls for computers running the OS.

For now, I'm going to assume I have the same issue that jwerx did and see what Dell and I can work out - still would have been nice if the issue could have been fixed next business day though.

 

Are you really actually using the ALS? I found it hopelessly bad at it's task and switched it off after 1omin. Ofcourse if you find it's that usefull it should work.

 

I installed Windows 7 64 on my M4400 last night and I was never able to get the ALS to work after that. Oddly, it did work for me in Vista 64 fine once I uninstalled all the Dell Control Point utilities. (With them installed, it worked only while on battery power; but without them, it worked all the time.)

But no luck in Windows 7, with or without the Control Point software. I, too, am able to dim the display manually though.

Another oddity was this afternoon, the display backlight went berserk and started changing lots of colors before it seemed go off entirely. (Or, actually, it was very dim and flickering.) But a restart brought it back and it's been fine ever since.

 

hmm, i had blue backlight only for short while, but pulling out the battery and replacing while the system was off fixed that.

also, i wish dell would reduce the minimum brightness of the RGB LED display! it gets very bright, and there are 15 levels of brightness, but the least bright isn't very dim. also, the backlight flickers slightly, occasionally.

 

confirm this - ALS doesn't work well in Windows 7. There was no problem in Vista... Looks like Dell software is simply incopatible with new Ambient Light Sensor service in Windows 7. Have to wait for update...

 

After several rounds of back-and-forth with Dell, the rep asked me to hold down the "d" key while powering up the computer. This puts it into a display test mode of some sort. Anyway, even though everything seemed okay to me, at the end of the test, the light above the F4 key was flashing. According to him, this meant my LCD needed to be replaced, so that's apparently in transit now.

My keyboard back-lighting is working fine under Win7, and after I asked the rep if this would suggest that the sensor itself is okay, he agreed. (They never think of these things themselves.) But after that "d" test, he said that he was confident a new LCD would fix my ALS problem.

Given that one moment I was running Vista 64 and the ALS was working, and the next moment I had upgraded to Win7 and it was no longer working, I'm skeptical that a new LCD will do any good at all. But I guess I'll see.