Daytime Running Light Problems and Solutions

Automotive light bulbs found in modern cars last longer, because of their one-piece construction. The ones manufactured in the 70s and 80s consisted of a glass bulb mounted to a metal base, which made them more vulnerable to failure. Late-model one-piece automobile lamps are so reliable that many cars go to the junkyard with the factory installed parts still in place and working.

One category of automobile lighting that does not share this long life and trouble-free operation is the daytime running lamps. Since they’re illuminated more hours than any other bulb mounted on the car, replacing them also comes with a higher frequency. In fact some cars have problems with melted sockets and wiring because of the heat generated from the extended on time.

Daytime Running Light Operation

Although this system is illuminated more than any other on the vehicle they are not on all the time. In fact, certain criteria must be met before they’re automatically turned on. Obviously the first thing required is, it must be daytime. In addition the car ignition needs to be in the run position and the bulbs won’t activate until the gear shifter is moved out of the Park position. Application of the parking brake can also prevent the bulbs from illuminating on some models.

Running Lamps Turn On and Off

This is designed to be an automated system so driver error can be eliminated. Another thing to understand about the system is the lights were not designed to be used in conjunction with other exterior lighting. If the headlamps are turned on or in the auto position and its dark enough outside the daytime running lights (DRL) will turn off and the headlights will be on. When light level rises outside and the headlamps go off the DRL will turn back on.

If the vehicle is started in a dark garage automatic headlight systems will turn on the low beams and when the vehicle is backed out, it can take up to a minute for the DRL to take over and turn on the daytime lamps. This automatic operation is courtesy of a light sensor that’s most often mounted in the top side of the dash panel near the base of the windshield. It’s also strategically placed so the windshield wipers do not cast a shadow on it.

Common DRL Problems

Since different manufacturers will illuminate different bulbs to meet the requirements, problems also vary between year, make and model. On General Motors trucks from the late 90s through the early 2000’s the DRL bulbs are located below the headlights. After years of driving around its common to find the sockets to be melted when you realize the DRL bulb is blown and attempt replacement.

These parts are available as replacement kits at many parts stores and General Motors dealerships. The kit comes with the socket, a section of wiring and crimp connectors that have heat shrink tubes on them to make sure water does not penetrate the repair. The new socket is a little more heavy duty and designed to withstand the extra heat.

A common DRL problem is verifying the correct operation. Since the bulbs won’t light when the parking brake is set or if the gear selector is in Park this becomes inconvenient for one person to check the bulbs are lit. There is a couple of ways to get around this. You can drive up to a reflective surface like a white painted wall or garage door and often see a glow. You can also block the wheels and with the key on engine off carefully remove the gear shifter from Park to see if they are working. It is however recommended to get a second person to help you check for proper illumination.

DRL Resistor Problem

On some 2005 through 2006 small sport-utility vehicles like the equinox, Saturn Vue and Pontiac torrent have reported problems with the DRL resistor. The part is located in front of the driver side wheel well and attaches with a single bolt out near the front bumper. Drivers have reported inoperative lights along with a dashboard notification. This may or may not be a good do-it-yourself project depending on your skill level. A new resistor will cost between fifty and seventy-five dollars just for the parts.

To recap daytime running lights won’t come on unless it’s light out and the vehicle is running down the road. Hence the gear shifter needs to be in a forward or reverse gear and ambient light must be at the level considered to be daylight. Since these safety lamps are designed to operate by themselves manually turning on any other exterior lighting will automatically turn the DRL’s off. Therefore, if you don’t want them to come on, turn on the parking lights, headlights or even the fog lamps.