So how does this rig handle interior lights?

[HiHoeSilver]

Not enough resistance. A lower impedance allows the driver circuit to push more power to the load. If the circuit isn't designed to handle this extra power, it can be damaged.

Same thing as putting speakers of lower impedance on an amplifier. The amp puts out more power, but it runs hotter. If it's not stable at those reduced loads, it can be damaged.

This was just a guess as I don't know exactly how these lights are driven and controlled. I don't know if they're dimmed by a rheostat or PWM. I'd guess rheostat since they're incandescent.


I'm wondering if the lights in question are on their own circuit and are in parallel. This would double the reduction in impedance of one LED and may be just beyond the threshold of the circuit.

True. Two things in my mind.

1. The "dim" condition on mine only happens when I manually turn on a map light, which is (a) infrequent, (b) short duration, (c) half of the time, I flip my visor to make it go full bright (assumingly based on the increased load).

2. There are 2 things that turn on the front map lights (the second row and cargo area have separate dome and map bulbs). One is with the dome lights in a lock/unlock event (including the fade to black). The other is the button. Since they act normally when the dome/ courtesy circuit is activated, and are only dim when individually turned on by the button, I'm guessing that the controller is smart enough to vary the power based on the resistance of the circuit.

I have admittedly not done real math or experimented with turning on all the map lights once at a time to see what happens. What I do know is that when I open the visor (still oem incandescent), the map light suddenly gets full juice. Leads me to believe that the controller is protecting itself when there's not enough resistance.

 

[SnowDrifter]

Oooookkay so we have a solution

Seems the initial hypothesis was right - those bulbs don't draw enough power to trip the power supply into full-send

I'm honestly content with having an odd dual brightness setup. Probably won't fuss with it now that I know how stuff worms.

BUT if anyone is interested I can dig into this further and start gathering data / running some tests do determine resistor values so it behaves as the stock bulbs do. Will get to that Monday when I can contact vleds for some detailed specs on the bulb

 

[SnowDrifter]

Don't feel like quoting; silver, I reckon the opposite is true.

Controller runs low power until it sees a draw then ramps up. Being that it stays dim, I'd reckon there's actually too much resistance (and by extension not enough current) to kick it into operation.

 

[SnowDrifter]

I'll do digging and bring certain answers on Monday. Hopefully this will help give some concrete answers and help some poor lost soul who finds it on Google

 

[HiHoeSilver]

Neat

Ok

So I reckon we have a solution.

Pulled diagrams and info from the service manual.

Basically the rig has an odd power supply circuit setup to avoid draining the battery. It seems to sense on/off by proxy and uses a low power signal, sees power draw when a bulb is turned on, then kicks on to full voltage.

Now I couldn't find any spec for what the threshold is for mode switching. But if you peek at the diagram, it would make sense that opening a vanity light or door or manually turning everything on would work. The whole system is in parallel.

It gets extra weird because they seem to run on 2 power supply circuits. One when the switch is off. One when the switch is on. When the switch is off, it seems to run through the constant lamp supply voltage. When the switch is on, it runs through inadvertent power supply voltage. Seems to fit with the behavior I was noting where door open would result in low/high brightness when toggling the switch. It's switching between 2 sources of power. One of which is low voltage and not seeing the trigger to deliver full power, the other of which is always delivering full power.

Sooooooo

This can be tested as mentioned above, by installing a light I know draws enough current; The stock bulb, and note it's behavior.

Could then be further tuned by installing a potentiometer and slowly decreasing the resistance until a suitable value is found.

Not sure if I'll make it to the second part as now that I think about it, having some odd low/high settings is interesting. But, I'll at least investigate the first bit tomorrow with a bulb swap on one side.

Regardless, I'll keep everyone posted on my findings.

Definitely a cooky setup

Awesome info. Was typing when you posted. Thanks for the recon! I will continue to enjoy my two light level options.

I figured out that I don't have the change based based on door position because I leave the dome override switch latched unless I want them on for something.

 

[ivin74]

I have an interesting "what the **** is going on" moment right now

Swapped map lights to led.

Turn on all lights with the dial, full brightness.

Open door, full brightness.

Close the door, turn it on with the button: 10 percent output.

Click the manual button with the door open, it dims from full to 10 percent

Open my visor mirror, pops back to full output and functions normally for the rest of the drive cycle.

Start a new drive cycle, behavior repeats.



I didn't note this behavior with the original bulbs. Both bulbs do this. I've verified they're seated all the way. And they're good ones too - no flea ay junk. Tried flipping the polarity and no change - these can be installed in either direction.

So what's the gig? I took a little peek up inside and didn't see any dimmer circuit. Given the specificity and consistency of the behavior I don't beleive it's a ground. Symptoms don't match with a power supply issue - toss original bulbs back in and they work as expected.

My map lights do the samething, I only noticed that with the LED bulbs.

 

[ivin74]

Mine does it too.

I have actually grown to like it because I get two levels of light from the map lights. They go full bright with the fob when unlocking 100% of the time.

X2

 

[BG1988]

I have an interesting "what the **** is going on" moment right now

Swapped map lights to led.

Turn on all lights with the dial, full brightness.

Open door, full brightness.

Close the door, turn it on with the button: 10 percent output.

Click the manual button with the door open, it dims from full to 10 percent

Open my visor mirror, pops back to full output and functions normally for the rest of the drive cycle.

Start a new drive cycle, behavior repeats.



I didn't note this behavior with the original bulbs. Both bulbs do this. I've verified they're seated all the way. And they're good ones too - no flea ay junk. Tried flipping the polarity and no change - these can be installed in either direction.

So what's the gig? I took a little peek up inside and didn't see any dimmer circuit. Given the specificity and consistency of the behavior I don't beleive it's a ground. Symptoms don't match with a power supply issue - toss original bulbs back in and they work as expected.

I used sylvania leds in my old GM car with no issue it was a 2003 though. the thing i miss not having is floor lamps..



LEDs saved my battery from going flat High powered 1 watt vs 5 watts..0.1amp draw vs 0.4 amps


left it on overnight

 

[89Suburban]

Good stuff here!

 

[iamdub]

Oooookkay so we have a solution

Seems the initial hypothesis was right - those bulbs don't draw enough power to trip the power supply into full-send

I'm honestly content with having an odd dual brightness setup. Probably won't fuss with it now that I know how stuff worms.

BUT if anyone is interested I can dig into this further and start gathering data / running some tests do determine resistor values so it behaves as the stock bulbs do. Will get to that Monday when I can contact vleds for some detailed specs on the bulb

So the dim light is a function and not a fault. My concern was a tiny amount of voltage was bleeding through and/or back-feeding a circuit. The two power sources explains it, but it's an odd setup, indeed. Thanks for the research!