Hey All, It was less than a month since I posted my intro I think LOL. I had parasitic draw and the truck wouldn't start after a few days. I was worried that it was some LED's that I put in for my head lights, DRL's and turn signals with soldered in resistors for the turns. I finally broke down after trying to chase it for a bit and had nothing but frustration and took it to a friends shop. He found the negative battery post was loose and replaced it and all seemed right in the world until that night when the DRL's were dimly lit up. I checked it with a volt meter and it's putting a bit more than 9v to each DRL. Because of other symptoms (door locks opening and closing randomly, nothing lighting up when I put the key in) I'm thinking its a head light switch, the ignition switch or the BCM causing issues. Any ideas where to start? How to test? I don't wanna throw copious amounts of money at it replacing parts but if it would be easier and less time to just try to replace both switches to start? Just because it's so cold I'm not looking to stand out there for hours on end testing. Maybe if I wait till the weather warms up?

TIA for the help!

2008 Chevy Tahoe, 5.3L gas/flex fuel LT.

 

Poor grounds are a common issue in the salt zone on an older vehicle. And there are a lot of grounding points.
That bad ground at the battery could have affected the cables. Poor connections generate heat, and it travels down wires.
As an example, my son had a Sable that was erratic cranking, new battery also, it would jump start fine. Negative cable was the issue, I had to use the car until it acted up in the driveway so I could diagnose it. Cable visually looked good, he had got the car used.

 

Hey all, so I replaced the ignition switch and for a while it seemed to have solved the issues but after a week or so something wierd happened. I wish I could remember now how it re-manifested itself. In the end I resolved the issue by selling it to the dealer that were buying another car from. 🚗 Hahaha! She was a great truck though! I'll miss her dearly. 😢

 

until that night when the DRL's were dimly lit up. I checked it with a volt meter and it's putting a bit more than 9v to each DRL.
TIA for the help!
2008 Chevy Tahoe, 5.3L gas/flex fuel LT.[/QUOTE]


It could be the DRL relay malfunction. Tracing back, it is controlled by the BCM, which in turn is triggered by the ambient light sensor. These are the black nubs sticking thru the grille, center dash under windshield.
PS There are some excellent fuse and location guides on line. Just google it. Also, if you ever want to disable the DRM's, a 1000 ohm resister across the nub will do it. Cheers. Wavelength.