I would test for a bad ground by putting a jumper wire between ground on the vehicle, and the ground for the bulb, and seeing if that increased the brightness. I believe your car uses an H4 type bulb with a 3 prong base. If you hold the bulb so you are viewing it from the back, with the middle prong at the top, the prong on the left is ground, the middle is low, and the right is high beam.