The 2006 Toyota Highlander is built with a dependable DRL (Daytime Running Light) system designed to automatically turn on your high beams at reduced power when the vehicle is in motion. If the DRLs suddenly stop working — even though your headlights, turn signals, and brake lights work — you’ll want to narrow it down quickly. Here’s how to do that.
How the DRLs Work
The DRL system is activated when:
- The ignition is ON
- The parking brake is fully released
- The transmission is in gear
- Ambient light is bright enough
- The headlight switch is OFF or in AUTO
It powers the high beam bulbs (9005) at a lower voltage using a dedicated relay and a DRL control module. The goal is to keep your Highlander visible during the day without using full headlights.
Step 1: Confirm the DRLs Are Actually Out
Start the engine, make sure the parking brake is fully released, and shift into Drive. Check the front of the vehicle. If the high beams don’t glow at reduced brightness, the DRLs are likely inactive.
Step 2: Parking Brake Switch
If the system thinks the parking brake is on, it won’t trigger the DRLs. Release the brake and make sure the indicator light on the dash turns off. If the light stays on, even a little, the switch might be stuck or misaligned under the pedal assembly.
Step 3: DRL Fuse
Open the fuse box under the hood (driver’s side) and look for the DRL fuse — typically a 10A or 15A. Use the diagram under the fuse box lid.
- Pull the fuse and inspect the metal strip inside
- Replace with the same amperage if blown
If it blows again immediately, there could be a short in the wiring or a faulty DRL relay/module.
Step 4: DRL Relay
The relay sends power to the high beams at reduced brightness. It may be labeled “DRL” or “Daytime Running Light Relay” in the underhood fuse box. Try swapping it with a similar one from a non-critical system (like the horn or fog light relay).
If the DRLs come back on, that relay was the issue. Replace it with a reliable part like the Denso 567-0010.
Step 5: DRL Control Module
This small electronic box usually sits near the driver’s side under the dash or kick panel. It receives inputs from the ignition, parking brake switch, and ambient sensor — then sends signal to the DRL relay.
If everything else checks out but DRLs still won’t activate, this module may have failed. There are no warning lights or codes when it does. Check for loose connectors or signs of corrosion. Replacements usually cost $50–$100.
Step 6: High Beam Bulbs
The DRL system powers the same 9005 bulbs used for your high beams. Even if your high beams work at full power, old or low-quality bulbs may not light up during DRL mode. Inspect and replace them if needed.
Upgrade to DRL-compatible LEDs like Fahren 9005 LED Bulbs for longer life and better visibility.
Step 7: Ambient Light Sensor
Some Highlanders have a sensor near the windshield that tells the DRL module whether it’s daylight. If it’s dirty, covered by a dash mat, or failing, the system may think it’s dark and default to low beams instead of DRLs.
- Clean off the sensor
- Make sure it’s not blocked
- Replace it if unresponsive
Step 8: Aftermarket Modifications
If you’ve replaced your headlights with aftermarket housings, HIDs, or non-DRL-compatible LEDs, you may have unintentionally disabled DRL function. Most LED kits require a higher voltage than DRL systems deliver.
Reinstall stock halogen bulbs to test. If DRLs return, look for a DRL-friendly LED kit with CANbus decoders built in.
Wrap-Up
When DRLs stop working on a 2006 Toyota Highlander, the most common causes are a bad relay, a blown fuse, old bulbs, or a faulty parking brake switch. Go step-by-step and start with the easy checks — fuse, bulbs, and relay — before diving into the DRL module or wiring. Most fixes are affordable and can be done in less than 30 minutes with basic tools.
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