Perhaps the most common problem that causes pickup truck headlights not to work is that the light bulb has burned out. Standard halogen bulbs typically last about five years or 50,000 miles, though their life can be significantly shortened or lengthened based on their frequency of use, amount of night time driving, and other factors. If one or both headlights have stopped working, but the pickup's tail lights or side marker lights work, the bulb may have expired. Most pickup truck bulbs can be replaced with new bulbs from a local automotive, though some high-end trucks (like the Lincoln Blackwood) may require special bulbs available from the manufacturer.
If both headlights stop working at the same time, and especially if other lights like tail lights and side marker lights have also failed, the problem may be traced back to the truck's fuse box. If the fuse powering the truck's lights blows, all electrical devices dependent on that fuse will stop working at the same time. Fuses can be replaced with manufacturer or generic fuses but use caution when replacing fuses as a blown fuse is often a symptom of other electrical problems.
If the pickup headlights fail to illuminate when the vehicle is not running, the truck's battery may be too weak to power them. This problem is common after the headlights or other electrical accessories have been left on for a length of time after the truck's ignition was turned off, and may cause difficulty in restarting the pickup. If the battery is discharged but not completely dead, it may be restored by receiving a jump start from a nearby motorist or from a portable device known as a "boost box." If the battery fails to maintain a charge even after the vehicle starts or being charged on a battery charger, it may have expired and should be replaced.
If the troubleshooting steps outlined in Sections One, Two and Three above do not resolve the headlight problem, there may be a more serious electrical problem in the pickup's internal wiring. Electrical problems like short circuits or brittle, broken wiring can cause the truck's headlights to fail, and identifying these issues requires careful tracing of the wires leading to the headlights from the driver-activated switch. In many cases, diagnosing internal electrical wiring problems is best left to professional mechanics with special tools used for identifying such issues, though the problem wire may be pinpointed with some patience, time, and methodical troubleshooting.
