If your headlights are dim than normal, then your problem might not be with the bulbs themselves, but it might, most likely, be with the wires connected with the blubs.u003cbru003eOne of the common reasons for this is a corroded ground wire. This wire connects the bulb circuit with your carâ€s chassis which is acting as the ground itself.u003cbru003eSo, if the wire is corroded or damaged, it will lead to disruption in electric flow, and will eventually produce low output in the blub.u003cbru003eAnother common problem can be the failing alternator. If your light switches with the engine reverse up and down, you can surely contact your technician to check this immediately.