2005 Chevy Truck real turn/brake lights

Hi thaynes,

Thank you for the donation.

The problem seems to be due to a bad ground circuit at the rear taillights.

Start by cleaning and retightening the rear ground connections.

can you tell me roughly were the grounds are in the rear? Do they ground though the housing or is there one main one to look for?

They are mostly grounded on the body. Check the rear waire harness near the taillights for any wires that are being attached to the body.

Let me know the exact vehicle model, engine and transmission type that you have so I can get the wiring schematic and ground location for you.

If you are not sure of the model, let me have the Vehicle Identification number ( VIN ).

The truck is a 2005 chevy 2500hd with the 6.0L gas and 4l80e trans and is a 4x4 I did find two ground wires and cleaned and re-tighten them, no change. The brake lights work when they are all you are using. Same for the turn signals. When the running lights are on then all the rear lights are messed up or if using the brakes then the lights are all lighting up. So does that mean the lights are trying to ground thought them selfs when more than one is working?

Yes, you are correct about the various lighting systems are trying to ground through themselves from rear to the front grounds.

The is a rear lamps junction but my database does not indicated where it is located. Try to locate this junction box and check if it is contaminated thus causing grounding problems.

The main ground connection for the junction box which joins all the various circuit grounds is at left side of fuel tank. Check it too if you have not done so yet.

You can try attaching a remote ground from any of the lght grounds to test if it resolves the problem.