Instrument cluster lights turn off when map light is turned on
- Thread starter dkad260
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you mentioned that the drivers side visor lights are burned out? If so I would try pulling the visor and unclip the wire harness and see if that makes any difference. Then check the resistance on both sides. body & visor.
interior and exterior lights are on different circuits so while goofy exterior lights can create havoc on ALL of the exterior lights the interior lights are not affected at least in my experience.
as for the rear hatch struts if the rear struts alone (without power assist) do not "lift" the hatch open all of the way after the rear has been manually lifted about 1/4th of the way or less then they are not good. In normal operation they work in conjunction with the power motor, the power motor alone is not strong enough to lift the hatch.
Yes, all 4 visor lights are out.
For this test, I have 12.25V at the battery. I haven't pulled any harness yet, but I removed the driver's side cover on the LH light....
with the mirror cover open, I have .171 V to ground on the top terminal, and .188 V to ground on the bottom terminal. With the mirror cover closed, I have 10.95V to ground on both terminals. With the cover open I have 1.8 M ohms to ground on both while showing .17 V
The rear hatch was good, I mistakenly turned off the liftgate with the overhead switch.
Hey @mikez71, likely not, but just in case my comment was taken the wrong way about replacing parts blindly, that was not directed to you...
The light switch switch is cheap and I wanted a spare BCM while they are still available, I also ordered a spare OE FPCM a while back just in case.
the visor could be the problem, it's 3 screws on the upper left corner pop the cover off, it's 3 screws and the harness is right thereYes, all 4 visor lights are out.
For this test, I have 12.25V at the battery. I haven't pulled any harness yet, but I removed the driver's side cover on the LH light....
View attachment 483188
with the mirror cover open, I have .171 V to ground on the top terminal, and .188 V to ground on the bottom terminal. With the mirror cover closed, I have 10.95V to ground on both terminals. With the cover open I have 1.8 M ohms to ground on both while showing .17 V
The rear hatch was good, I mistakenly turned off the liftgate with the overhead switch.
Hey @mikez71, likely not, but just in case my comment was taken the wrong way about replacing parts blindly, that was not directed to you...
alternatively compare those readings to the passenger side. * readings may or may not be the same, there basically on the same circuit.
the contact for the switch is at the top center of the flap/cover
there is a plastic nub with metal on the edge, when opened the nub pushes in and makes contact on the switch, which then provides voltage to the lamps.
I have never checked but I would assume the switch is normally open, and grounded (closed circuit) with the flap opened.
there is a plastic nub with metal on the edge, when opened the nub pushes in and makes contact on the switch, which then provides voltage to the lamps.
I have never checked but I would assume the switch is normally open, and grounded (closed circuit) with the flap opened.
With the mirror cover closed, I have 'OL" measuring ohms to ground on both terminals, cover open is 1.8 M Ohms to ground.
well then it's probably not the problem, those other readings are weird though
one of the contacts will be power and one will be ground, testing them together should read up to 12v (lid opened)
the positive should read up to 12v's, read with a separate ground and the ground should have basically 00 ohms to a separate ground
anyway it was worth a try, the problem may lie elsewhere... finding it may be difficult
have you checked the dome lights for any ground shorts?
No not yet, but all the dome lights work. All the map lights work as well with the door open, they just won't turn on with the door closed, but the map lights will turn on when I turn the interior dimmer switch to the 'ON" position.
mikez71
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Hey @mikez71, likely not, but just in case my comment was taken the wrong way about replacing parts blindly, that was not directed to you...
Not taken that way, and even if you did it's OK
I know how you feel about all these modules. They might not be available soon.
Then you need to get a used junkyard one.. then they need re-programming...
Sometimes I can read the diagrams alright, but sometimes they make my head hurt...
if none of this is causing battery drain then I would suspect maybe a open ground somewhere in the dome light circuit is my best guess
doors open would theoretically create a ground, doors closed that ground is not in effect and dome lights have lost there ground., which is somehow affecting the cluster
maybe a pinched or melted wire somewhere...... just spitballing
have you checked every fuse? gm likes to hitch a ride on other seemingly unrelated fuses sometimes.
mikez71
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Did you check both fuses?
Diagram shows CTSY and IS LPS fuses..
Since activating any map light dims the cluster, I think it must have to do with the map light power source, which goes through BCM, which controls all lighting..
And when you say map lights work with door open, dimmer switch on, that is the courtesy power source and not the map light (buttons) power source.
When I have my courtesy lights on, hitting the map buttons will make the light slightly brighter. It's swapping power sources. Yours swaps too, but your map power source is bad, so it turns off instead.. and the cluster dimming must be some issue in the BCM when trying to power the map circuit.
I'm stumped if it's not the BCM..
Diagram shows CTSY and IS LPS fuses..
Since activating any map light dims the cluster, I think it must have to do with the map light power source, which goes through BCM, which controls all lighting..
And when you say map lights work with door open, dimmer switch on, that is the courtesy power source and not the map light (buttons) power source.
When I have my courtesy lights on, hitting the map buttons will make the light slightly brighter. It's swapping power sources. Yours swaps too, but your map power source is bad, so it turns off instead.. and the cluster dimming must be some issue in the BCM when trying to power the map circuit.
I'm stumped if it's not the BCM..
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I did this AM..both are good.
This junction looks like it's worth a look, now I just need to find it if not the actual connector to the BCM.
mikez71
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Agreed.
Although I am still leaning towards BCM since cluster lights dim.
If no power, hitting map switch should turn off courtesy, map lights won't work, but cluster shouldn't be affected?
If it was a constant short in the map light circuit, it should dim the cluster whether the button is pressed or not?
If only one bad switch, other switches should work?
When you have courtesy (dimmer) lights on, if you hit the map button a second time, are the dome and cluster lights restored? (just want to verify the map button toggles)
Although I am still leaning towards BCM since cluster lights dim.
If no power, hitting map switch should turn off courtesy, map lights won't work, but cluster shouldn't be affected?
If it was a constant short in the map light circuit, it should dim the cluster whether the button is pressed or not?
If only one bad switch, other switches should work?
When you have courtesy (dimmer) lights on, if you hit the map button a second time, are the dome and cluster lights restored? (just want to verify the map button toggles)
What happens is, with the doors closed, headlights on, also with the ambient being dark so the dash sensor now dims the dash for evening illumination intensity, or if I cover the photo sensor during the day for this test..if I select ANY of the 4 overhead map light switches, the IC lights will dim, and none of the 4 map lights will turn on if I repeat this for the next 3 map lights.
Same scenario now with the IC light intensity now turned to full brightness and to the detent that turns on the interior lights, if I now press ANY map light switch, which are all illumated, only the map light I press now turns off, leaving the rest illumated as well as the overhead lights stay illumated. None get brighter.
Within the same test conditions, If I pull down the visor, the IC lights will dim.
None of the visor lights are working, None of the steering wheel lights are on except for the inner, center button on each side.
What you say makes sense with the 2nd power source which it seems the power draw is causing the lights to dim.
Something else, if I turn the IC intensity up all the way, before turning the interior lights on, the IC lights won't fully dim when turning on a map light, only if I have the intensity at about half or lower....where it seems there's enough current to overcome a possible draw from the map lights. The IC lights don't just shut off, they lose intensity...so when turned up all the way, you don't notice the dimming.
Also, is the center clear cover a light? It does not illuminate.
Same scenario now with the IC light intensity now turned to full brightness and to the detent that turns on the interior lights, if I now press ANY map light switch, which are all illumated, only the map light I press now turns off, leaving the rest illumated as well as the overhead lights stay illumated. None get brighter.
Within the same test conditions, If I pull down the visor, the IC lights will dim.
None of the visor lights are working, None of the steering wheel lights are on except for the inner, center button on each side.
What you say makes sense with the 2nd power source which it seems the power draw is causing the lights to dim.
Something else, if I turn the IC intensity up all the way, before turning the interior lights on, the IC lights won't fully dim when turning on a map light, only if I have the intensity at about half or lower....where it seems there's enough current to overcome a possible draw from the map lights. The IC lights don't just shut off, they lose intensity...so when turned up all the way, you don't notice the dimming.
Also, is the center clear cover a light? It does not illuminate.
I haven't read through all of the details but it makes me wonder if there's a deficient body ground somewhere, causing the ground to come through the wrong circuit. Just a thought. Maybe try a voltage drop test to rule it out?
mikez71
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The reason I didn't think it was a ground issue, because the map and dome both use the same ground.
The BCM has two grounds, they are shared with various other things...
G103 = ECM & TCM
G201 = headlamp switch, wiper motor, turn signal, etc..
BUT that doesn't mean the BCM has a good ground connection on both..
The BCM has two grounds, they are shared with various other things...
G103 = ECM & TCM
G201 = headlamp switch, wiper motor, turn signal, etc..
BUT that doesn't mean the BCM has a good ground connection on both..
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Call my self reading all of this but have u removed the LED lights and see if it is still a problem?
well i'm back to checking the visor harness again then
"Within the same test conditions, If I pull down the visor, the IC lights will dim"
simply pulling down the visor should do nothing of any kind, same if you flipped the mirror lid open. All it should do is turn the mirror lights on or off, this affects nothing else.
day time, night time, key on, key off, lights on, lights off, none of that has anything to do with the visor lights
you can pull down the visor, open the mirror lid, close the door and lock the vehicle and the mirror lights will still be on while everything else goes off.
"Within the same test conditions, If I pull down the visor, the IC lights will dim"
simply pulling down the visor should do nothing of any kind, same if you flipped the mirror lid open. All it should do is turn the mirror lights on or off, this affects nothing else.
day time, night time, key on, key off, lights on, lights off, none of that has anything to do with the visor lights
you can pull down the visor, open the mirror lid, close the door and lock the vehicle and the mirror lights will still be on while everything else goes off.
I would unplug both of those visors and see if anything changes
I'm sorry, I misspoke....not when I pull down the visors, only when I open the vanity mirror door.
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