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Light sensor replacement

Old Dec 19, 2025 | 12:26 PM
  #1  
desertrat's Avatar
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From: Palm Desert, CA
Light sensor replacement

The light sensor on the top of my dash is defective, replacment is easy after the top dash panel is removed. Has anyone ever removed this panel or have access to a diagram or video? I have searched online a lot and can't find a thing. The dealer was reluctant to do it because a new part isn't available if they broke this one.
Any help is appreciated. I know it just pops off like a door panel and I just need to know where to pry.
I held a bright flashlight up to the sensor with no results, but I can dim or brighten the dash lights with my scanner, so the circuitry seems OK. The scanner indicated a bad ambient light sensor with a code.
I can make the dash lights normal if I turn the 'AUTO' lights off.
Old Dec 19, 2025 | 12:31 PM
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More information

Search and you will find many more informational threads in the way back machine!

https://www.chevyhhr.net/forums/how-...removal-62382/

And here includes an exploded view of the dash

https://www.chevyhhr.net/forums/audi...ash-top-36135/

Last edited by Oldblue; Dec 19, 2025 at 12:34 PM. Reason: To provide more information
Old Dec 19, 2025 | 04:47 PM
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Only around 6 screws? Not too complicated, it seems. It helps to use better key words in my search, thanks!
Old Dec 26, 2025 | 01:02 PM
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Curious, what’s the symptom of the bad sensor?
Old Dec 28, 2025 | 06:58 AM
  #5  
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The dash lights stay dim during the daytime, the only way to make the bright (normal) is to turn the AUTO lights off. You can also use a scanner to verify. Mine is no good, so the dash has to come apart to a degree.
Old Dec 28, 2025 | 02:08 PM
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Caught my attention because I have another GM car, that intermittently only shows me dim displays in the daylight. I can't help wondering if opening or shorting. The sensor circuit might just result in the BCM thinking it's daylight all the time. This would result in in an excessively bright nighttime display, of course, but that could be turned down manually.
Old Dec 28, 2025 | 06:36 PM
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Oldblue and I both told you before, it's operating as designed. When DRLs are on, instrument panel lights are off. From the 2007 owner manual, page 164.

2008 owner manual, page 3-16, says the same.

Old Dec 28, 2025 | 09:28 PM
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X2 ^^^
Old Dec 29, 2025 | 12:00 PM
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I ran a scan on the HHR this morning and here are the results pertaining to the ambient light sensor. It isn't the position of the light switch, I owned another HHR for 16 years and when the switch was in the AUTO position the dash lights would brighten and dim based on ambient light (day and night). If I switch to 'OFF' the dash lights are bright with this HHR.
When I issued the command to DECREASE the ambient light sensor voltage, the dash lights became bright (normal). INCREASE made them dim again. This proves an obviously defective sensor.
Opinions?

This is the default setting of the light switch. The dash lights should dim or brighten based on ambient light.
This is the default setting of the light switch. The dash lights should dim or brighten based on ambient light.

This is what the BCM sees from the the ambient light sensor in bright daylight with the engine running. The dash lights should be bright, but they are dim as if it were night.
This is what the BCM sees from the the ambient light sensor in bright daylight with the engine running. The dash lights should be bright, but they are dim as if it were night.

This is what the scanner reads. Its not the position of the switch, the problem is the sensor.
This is what the scanner reads. It's not the position of the switch, the problem is the sensor.

This is the fault code, but it doesnt activate an MIL. This cannot be erased.
This is the fault code, but it doesn't activate an MIL. This cannot be erased.
Old Dec 29, 2025 | 12:35 PM
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What position was the stalk switch in when the scanner was used? When a switch is off it shows as an open circuit. When you turn the stalk to anything beside "auto" the sensor is off. The switch turns the sensor on or off.
Do the headlights/taillights turn on at darkness? If the tails and markers turn on the sensor is working.
I always found that the dash lights changed a lot during the day; sometimes dim, sometimes bright, sometimes off. Mine was always on auto after my first dead battery on my first night of ownership.
Have you considered the dimmer switch?

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