Headlight one side works on bright the other side works on dim

Your headlight brightness is unlikely due to battery; it's more likely due to bad ground connection on both sides. There should be a wire coming from each headlight connected to the car's chassis. Check that the connection is tight and not corroded. Clean and reattach as needed.

bad connection or bad earth check all connection or bulb

Remove headlight and check electrical connection socket for corrosion on connecting pins.

You may have a loose or corroded headlight ground to the body, the ground wires are in most GM attached to the body near the headlight under the hood. Check all the grounds you can see on the inside of the fender, tighten and clean the with a wire brush, also check the headlight connector for problems like corrosion or not fully seated to the headlight bulb.

If the headlights were not changed at the same time the dim one may be about to go out. If you change the dim one and not both of them the other one will most likely get dim while the other is still bright

I am sure that a 12 Volt bulb means it needs 12 Volts. Since you changed the bulb to the other side, why not check the voltage in the working side and see what it reads?

Sometimes the turnstalk can interfere with the lighting. Try pushing the Hazard switch several times and see if the headlights straighten out. I read that too much goes through the turnstalk and that using the Hazards can derail a contact inside the stalk.

If this does not help, you may need a headlight relay in the powerbox. One contact may be dirty or burned down for the wire it feeds. Unless you have a single wire feeding both low beams to the headlights, I would bet the left and right side come out directly through the relay.

go here. we can help you. Also, did you check the headlamp relay in the box under the hood? One relay is in box in front of battery, other is in narrow box along passenger side fender under the hood. swap left & rt headlamp relays to see if it changes.

http://groups.yahoo.com/group/villagerquest/

There are two adjustment points (screws). For example left headlight: you will see one point near the end of left wing, at bottom side through a wing hole. This is for vertical plane headlight beam adjustment (up-down). Another one point is against water radiator side. This is for horizontal plane headlight beam adjustment (left-right).
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It's the dimmer switch in the column.

You have a bad ground, look out by the battery for a bunch of black wires screwed to the body of the car, check that they have a clean and tight connection, scrap off any paint under the wires.