Anyone know why this happens?

[yukon06]

First off, Hi all im new here....first post.
I picked up a real nice '06 yukon sle yesterday....lots of miles but meticulously maintained with all records....that said theres a couple minor issues ill ask about in other threads when I have time but for the moment here's one...

I noticed when i want to turn on interior lights on the overhead i hit the button or buttons if im turning on both and they come on but not bright at all. If I open the door however, they come on as they should but twice as bright as compared to when door is closed and I manually turn on.

Is this normal or am I having an issue somewhere and if it is normal how can I make them to be bright when I manually turn them on?

 

[DougAMiller]

That sounds like the incandescent bulbs that originally were in those lights were replaced with LED bulbs. That is typical behavior in these trucks if you replace the overhead bulbs with LEDs.

 

[yukon06]

Thanks
Is there a solution to keeping the led and making it work or do i need to get different bulbs?

 

[Doubeleive]

Thanks
Is there a solution to keeping the led and making it work or do i need to get different bulbs?

that's a good question, it's a voltage thing with a incandescent bulb you won't likely notice it so maybe a different brand led? or just go back to a stock bulb

 

[DougAMiller]

It is possible, but can get a bit complicated. I have done it in my Tahoe. I added resistors wired in with the bulbs to produce the same current draw as the incandescent bulb. However, the resistors get extremely hot if the light is on for more than a minute or two. When I first installed them I actually had one of the resistors melt through the overhead console plastic and I had to replace it. So, I added a capacitor to cut off the current through the resistor after a few seconds, but the capacitor will power the LED for two or three minutes after the light switch is turned off, so I added another resistor that drains the capacitor and causes the LED to fade out in 3-4 seconds. The fade time can be adjusted by choosing different size resistors. So, they work great now and it has the fade-out feature that the newer cars have, but as I said, it's a bit complicated and you have to duplicate this on every bulb.

 

[Fless]

You could verify the cause and effect by replacing the LEDs (if that's what's been installed) with the correct incandescent bulbs, and that would give you some direction.

 

[MassHoe04]

Looks like one of those trade-off situations, where you can have one thing or the other, but not both things at the same time...
The solution that @DougAMiller worked out is some great engineering, but does seem pretty complicated for the average Joe to bother tinkering with. Maybe Doug can go into business and make up plug-in LED that has all the bits built-in to make it all work as we would like them to... I am sure there would be a fair amount of demand for something plug-and-play...

Choices might be limited to keeping what you have, including the quirks or going back to stock incandescent bulbs.

 

[Doubeleive]

You could verify the cause and effect by replacing the LEDs (if that's what's been installed) with the correct incandescent bulbs, and that would give you some direction.

it's a led issue for sure, presuming he has led's installed, I had the opposite problem on my 03 silverado I put led's in it and opening the door produced very little light output, but pressing the overhead button gave it full power. regular bulbs had no issue.

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

You are already receiving sage advice from the knowledgeable folks on this Forum.

Interestingly enough, I replaced all incandescent bulbs on my truck, and I never noticed a difference in the overhead lights' brightness, when using the inside switch versus the door switch. I'll have to look more closely at this phenomenon the next time that I use my truck.

UPDATE: I checked today, and the brightness of the interior LED dome lights do not change in brightness, whether using the inside switch or opening the door to activate the door switch. Maybe, it my 07 year.

 

[DougAMiller]

This has to do with how GM designed the "Inadvertent Power" circuit in these trucks. This circuit in the BCM puts out a low-current level on the 12V supply for the interior lights and when it detects the voltage drop from a light being turned on, the BCM turns on full power. It then turns it off after 15-20 minutes to prevent the battery from being run down. The issue with LEDs is that they don't place a large enough load on the circuit to pull the voltage down enough to trigger the BCM, but the low-current level supply is enough to dimly light the LED. The reason that the door turns the light on full brightness is that all of the interior lights come on at once and the combined load of all of the LEDs triggers the BCM, but when you turn on only one or two it's not a large enough load.

You can add a circuit like the one I created shown in the image below and connect it to each LED bulb that has its own switch and it will produce an extra load for a short time when the switch is turned on, which triggers the BCM to go to full power mode. The capacitor then shuts down the extra load of the big resistor after a few seconds so that it doesn't overheat. The small resistor quickly drains the power out of the capacitor when the light is turned off, thus causing the fade out of the light. The 15k resistor I used gives about a 3-4 second fade out time, but by changing it to a larger or smaller value you can increase or decrease the fade time.