It’s a common problem on ’99-’06 General Motors fullsize trucks and SUV, and we’ve all seen the symptoms: running around with only one daytime running light (DRL) working, or none at all. Simply put, the bulbs and sockets simply roast themselves to death over time due to the high amount of heat produced by the factory-spec incandescent bulbs. This can also cause the original reflective coating inside the light housing to eventually flake off, requiring ultimate replacement of the lower turn signal and DRL housing itself.
We recently replaced the front headlights and turn signals on an ’04 Chevy Avalanche
. At the time of the replacement, we also put a fresh set of OE-spec bulbs in the housing as well. We noted some discoloration of the DRL sockets, as well as some distortion and brittleness. The reason the DRL sockets are so prone to this is because they’re essentially always on. If the truck is in drive or reverse, with the parking brake off, the DRLs are on. When the headlights are switched on, the DRLs turn off, but if you’re driving during the day, the DRLs are always on.
Having recently installed LED accent lighting and taillights from Anzo USA, we decided to continue the LED transformation by replacing the DRLs with 3156 LED replacement units from Anzo USA. We were initially concerned about the fitment due to the LED bulbs larger physical size than the stock incandescents, but upon further inspection and measurement, determined they would fit behind the new lower housings’ horizontal LED strip. To ensure long life and cool operation, we also opted to replace the DRL bulb sockets as well with a new set of AC Delco factory replacements from RockAuto. The job was quick, straightforward, and took less than an hour start to finish. If you have a “Cyclops” DRL in your GM truck, or notice significant discoloration or cracking on the DRL sockets, this is an easy low-cost fix for the problem.
| The first step to access the lower turn signal/DRL housing is to remove the upper headlight housing. There is an L-shaped pin at the top of the housing that pops and slides out allowing for easy removal of the unit.
| Unplug the headlight harnesses and set the upper unit aside. This will allow you easy access to the lower turn signal/DRL unit.
| The turn signal/DRL unit removes easily by pinching the tab on the outside edge on the back of the housing. The housing should pop out easily.
| Twist and remove the turn signal and DRL sockets from the housing. You will need to apply gentle pressure to the plastic locking tabs, and turn them counter-clockwise (from facing the rear of the housing). Put the housing aside.
| As you can see in this photo, the original DRL housing is brown, discolored, and distorted, due to hundreds of hours of use in constant high-heat conditions.
| Here is the stock incandescent bulb next to the replacement Anzo USA LED bulb. Although the Anzo bulb is more cylindrical in shape, it is about the same overall length as the stock bulb. You can see the browning and discoloration at the base of the incandescent bulb. Keep in mind these bulbs were new less than a year ago, and already show this level of deterioration.
| Peel back some of the wiring loom that covers the two wires going to the DRL socket. Going about 6-8 inches back from the socket, cut the wires. Make sure the ignition or accessory mode is “off” when doing this. If it makes you feel more comfortable, you can disconnect the battery.
| The new AC Delco harnesses come with plenty of excess wire to cut to the needs and condition of your socket and wiring. We ended cutting off about 6-8 inches of excess. With a wire-stripping tool, remove about 1/4-inch of the protective plastic off the end of both wires of the new socket. Likewise, strip off a similar amount off the wiring on the vehicle.
| The replacement DRL sockets come with a crimp connector included. Insert each end into the crimp connector and crimp. Which wire you connect to doesn’t matter, as it just completes the circuit either way.
| If you have shrink tube connectors, you can use those or simply cover the connection with electrical tape, like we did.
| We re-covered the connection with the wiring loom as much as we could, and wrapped it with electrical tape.
| Put the new Anzo LED bulb in the socket. With the parking brake on, put the vehicle in accessory mode, and put in drive. It helps to have a friend do this. The new LED DRL should illuminate. If it does not, flip it around in the socket. The bulbs are polarity-specific, even as the sockets themselves are not.
| Plug back in all the harnesses and reinstall any sockets in their respective housings. The rubber gasket surrounding the DRL socket is very grippy, so firmly twist it back into the housing.
| The upper headlight and lower turn signal/DRL housings go back in much the way they came out. Make sure they’re securely fastened with their respective mounting tabs or pins.
| The new Anzo LED bulbs give the DRLs a cool look, both literally and figuratively. The new bulbs should put off much less heat than the original incandescents, as well as keeping the sockets in better shape for much longer.