why are my head lights doing this

hello both my low and high beams are on at the same time passenger side are really dim and drivers side one is bright and 1 dim does any one know why

Need some more details on your ride.

Sounds like you have corroded/burned wiring.

IIRC the headlights are negative switched... this is why the quad beam mod works when you ground the low beams. Check your headlight wiring harness for wires that may be grounding out, starting with the side they're both dim on.

The one that is bright on the drivers side, is it the low beam?

check plug at the headlight sometimes they corrode and dont get good contact.

As mentioned, we need to know year, make, model, 2 door or 4 door, and if it's a Blazer ZR2 or not.

Check the ground circuit and connections for all lights first. In my experience, such dim lights is often a ground wire problem.