The 2021 Ford F-150 comes packed with modern lighting tech — including LED daytime running lights (DRLs) that help other drivers see you even when your headlights are off. But when those DRLs suddenly stop working, you’re left wondering if it’s a fuse, a setting, or something more complicated.
Let’s break down what causes this problem and how to get your DRLs back online, step by step.
How DRLs Work on the 2021 F-150
On the 2021 F-150, the daytime running lights are LED strips built into the headlight housing. They turn on automatically when:
- The ignition is on
- The headlight switch is in AUTO
- The vehicle is in gear (Drive or Reverse)
- The ambient light is bright enough (daylight sensor)
If any of these conditions aren’t met, the DRLs won’t activate. They’ll also shut off when the headlights are on fully.
Step 1: Check DRL Settings in the Touchscreen
The 2021 F-150 allows you to turn DRLs on or off using the SYNC 4 system. Here’s how to check:
- Tap the vehicle icon on the SYNC touchscreen
- Navigate to Lighting settings
- Make sure “Daytime Running Lights” is toggled ON
If this setting is off, the DRLs won’t come on no matter what. It may reset after a battery replacement or software update.
Step 2: Check the Ambient Light Sensor
The DRL system uses a sensor on the dashboard to detect lighting conditions. If the sensor fails or is covered by a dash mat or object, the truck may think it’s dark and disable the DRLs.
Make sure the area near the windshield (center of the dash) is clear. Try removing any coverings and restarting the truck.
Step 3: Test in Gear
In many F-150 trims, the DRLs only come on when the truck is shifted into Drive or Reverse. So if you’re testing them in Park, they may not light up.
- Start the truck
- Put the headlight switch in AUTO
- Shift into Drive and walk around to check the lights
Step 4: Check the Fuse Box
The 2021 F-150 has two fuse boxes — one under the hood and one inside the cabin. Use your manual to locate fuses related to “Exterior Lighting” or “DRL Module.” Fuses vary by trim and lighting package, but you’ll want to check:
- F43, F44 (DRL/Exterior Lamps — varies by model)
- F21, F22 (Body control module and lighting circuits)
Use a fuse puller, check for breaks, and replace any blown fuse with the same amperage.
Step 5: Inspect Headlight Wiring and DRL Connectors
If one side is out and the other works, it may be a connector or wiring fault at the headlight assembly. Remove the headlight housing if needed and check:
- That the DRL connector is seated properly
- There are no frayed wires or corrosion in the plug
Moisture inside the housing or a recent headlight swap (LED mod) can also cause the DRLs to stop working. Re-seat all connectors and clean with contact cleaner if needed.
Step 6: Check for Software Updates or Fault Codes
Since the DRLs are controlled through the BCM (Body Control Module), software glitches can cause them to act up. Visit the FordPass app or a dealership to check for pending updates.
You can also scan the truck for codes using a tool like the BlueDriver Pro OBD2 Scanner. Look for codes related to the lighting system, BCM, or DRL circuits.
Step 7: Check for Aftermarket Wiring Conflicts
If you’ve added aftermarket headlights, light bars, or a remote starter recently, the wiring may interfere with the factory DRL circuit. Some kits disable the DRLs or confuse the BCM.
Disconnect any new accessories temporarily and see if the DRLs return. If so, you may need to rewire them or use a CANbus-compatible setup.
Step 8: LED DRL Failure — Assembly Replacement
If one side of the DRLs is out and everything else checks out, you may be dealing with a failed LED strip. On the 2021 F-150, the LED DRLs are built into the headlight assembly. They aren’t serviceable, so if the LEDs fail, you’ll have to replace the full housing.
OEM headlights are expensive — over $800 apiece — but you can find high-quality replacements like the AlphaRex Pro Series LED Headlights for around $1,200 per pair.
Final Thoughts
When DRLs stop working on the 2021 F-150, start with the simple stuff: SYNC settings, fuse check, light sensor, and being in gear. Most issues can be traced to one of these before diving into module replacements or electrical teardown.
If everything checks out and the DRLs are still dark, consider scanning the truck for codes — or visiting a dealer if it’s still under warranty. It might just be a software reset away from working again.
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