Symptoms
- Turn signal light stays on solid instead of blinking on that side
- DRL brightness looks uneven between the two sides
- Dash turn signal indicator blinks fast or irregular
- Issue only appears on one side of the vehicle
Likely causes
- CommonFailing dual-function bulb (DRL and turn signal combined)Some vehicles use one bulb for both functions, and a partial failure can affect blinking specifically.
- PossibleFaulty turn signal flasher circuit for shared-bulb systemsThe flasher logic for combined DRL/signal bulbs can be more complex and prone to specific faults.
- PossibleWrong replacement bulb type installedUsing a standard bulb instead of the correct dual-function type can cause improper operation.
What to do
- Check your vehicle's specific bulb configuration to confirm if DRL and turn signal share one bulb on the affected side.
- Compare both sides' DRL brightness, since an uneven look can indicate a partially failing shared bulb.
- Replace the bulb with the exact correct dual-function type specified for your vehicle.
- Test the turn signal again after replacement to confirm normal blinking has returned.
- Check the fuse box for a fuse specific to the shared DRL/signal circuit.
- Avoid substituting a standard single-function bulb, which can cause exactly this kind of malfunction.
- Have a shop check the flasher relay if a proper replacement bulb doesn't resolve the issue.
- Confirm bulb part numbers carefully, since dual-function bulbs look similar to standard ones but wire differently.
Tools and parts
- Owner's manual or parts lookup (to confirm correct bulb type)
Dual-function DRL/turn signal bulbSearch: “dual filament DRL turn signal bulb for [your car make model year]”
When to call a pro
Double-check the exact bulb part number for your vehicle before buying, since dual-function bulbs are easy to mix up with single-function ones.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.