Flickering lights

[solli5pack]

So after watching a ton of videos I started doing voltage drop tests. Everything test good inside the engine compartment. I pulled the passenger seat just to check those grounds(there's two locations bolted to the body) under the seat and they check fine. So I wanted to check the grounds by the windshield under the dash but unfortunately I went to pull the front dash panel and it started to crack like a potato chip..taking a break an planning next steps. So when I open the door and the truck wakes up all the grounds go to high resistance so I'm assuming somewhere a ground is bad and when I eventually find it I should see some voltage drop on it.

 

[Doubeleive]

So after watching a ton of videos I started doing voltage drop tests. Everything test good inside the engine compartment. I pulled the passenger seat just to check those grounds(there's two locations bolted to the body) under the seat and they check fine. So I wanted to check the grounds by the windshield under the dash but unfortunately I went to pull the front dash panel and it started to crack like a potato chip..taking a break an planning next steps. So when I open the door and the truck wakes up all the grounds go to high resistance so I'm assuming somewhere a ground is bad and when I eventually find it I should see some voltage drop on it.

Dorman front dash piece replacement. they seem to match up good a couple of us have bought them

Amazon.com

I would be checking your interior dome lights those have come up as a issue before, apparently they can ground out on the roof?
the gmt900's are not like the k2's where half the truck wakes up when you open the door
interior lights, puddle lights if night time, cluster sort of wakes up, security maybe, door locks, power seats, bcm.

maybe do a test by leaving the drivers window down, leave it unlocked, let it go to sleep, then just open the drivers door and see if it still happens or if it only happens if you use the fob or manually hit the door lock button

 

[Doubeleive]

and that module def needs a repair to the harness

 

[solli5pack]

Got the dash pad off and both the grounds test good. It's definitely the dome light causing the issue. I can recreate the high resistance on the grounds just by reaching in the window and turning a dome light on. Anyone have advice on how to pull the front light assembly down from the headliner? It's not cooperating and I'm trying not to break it.

 

[Doubeleive]

Got the dash pad off and both the grounds test good. It's definitely the dome light causing the issue. I can recreate the high resistance on the grounds just by reaching in the window and turning a dome light on. Anyone have advice on how to pull the front light assembly down from the headliner? It's not cooperating and I'm trying not to break it.

should be 2 screws and 2 clips
and if I remember correctly you pull it from the front at the windshield once the two screws are out, the screws should be accessible once the dome light covers are removed, those just pop off with care.
just be cautious I did break one myself and I was kinda mad about it
I replaced mine a few years ago because almost all the bulbs were burned out and broke one in the process, nice used ones usually run about $50-60 on ebay
the good thing about it is all the pieces are easily swapped out once you have it off

 

[solli5pack]

should be 2 screws and 2 clips
and if I remember correctly you pull it from the front at the windshield once the two screws are out, the screws should be accessible once the dome light covers are removed, those just pop off with care.
just be cautious I did break one myself and I was kinda mad about it
I replaced mine a few years ago because almost all the bulbs were burned out and broke one in the process, nice used ones usually run about $50-60 on ebay
the good thing about it is all the pieces are easily swapped out once you have it off
View attachment 437247

Thank you. I got it off without breaking it! And I'm testing voltage on the ground at the connector for the dome lights! About 3/4 of a volt. According to all data the ground for the lights is G200 which I believe is the passenger side under the dash panel. I'm getting zero volts on the body grounds under the dash. So somewhere up in the headliner the wire must be coming in contact with the body? I guess I should pull the center lights to try and isolate.

 

[solli5pack]

Well the flickering has been eliminated. Corrosion in the RH side junction box in the dash.

 

[mikez71]

Good work! A new place to check for electrical issues!

A good one to add "SOLVED" to the title..

 

[solli5pack]

Good work! A new place to check for electrical issues!

A good one to add "SOLVED" to the title..

Yes! Thanks. Couple mistakes I made sent me down a rabbit hole tearing apart the interior of the truck looking for a ghost.

#1 You cannot measure resistance on a ground while current is traveling through the circuit. So on a vehicle it must be pretty much asleep before testing.

#2 Shouldn't measure voltage drop on a ground at the device such as, dome lights. The other devices on the circuit are going to pull voltage onto the grounds. Voltage drop checks should be done at the main ground locations.

If anyone feels different please correct. It wasn't until I started taking comparative readings on my Suburban that I realized what I thought what I was seeing on the meter as defective outputs were actually normal conditions and then noticed the flickering was gone after cleaning the junction box. I'm thinking the only real way to track down corrosion issues is to actually physically track them down and see the corrosion. I guess that's why @Doubeleive is always telling everyone with electrical issues on 15 yr old trucks to "replace the battery cables"!

 

[Doubeleive]

Well the flickering has been eliminated. Corrosion in the RH side junction box in the dash.
View attachment 437583View attachment 437584

where exactly? right hand side edge dash behind the cover? or is this somewhere under/behind the glove box