Add C-Light DRL Function to Your WRX or STi
The Diode Dynamics DD4055 DRL Harness lets your Diode Dynamics C-Light Switchback LED boards double as a daytime running light. It deactivates the factory daytime running light and powers the C-Light instead, while your high beam continues to work normally. DD4055 uses OEM-style connectors for a plug-and-play install with no cutting or splicing.
Key Features
- Allows the C-Light to also function as the daytime running light
- Deactivates the factory DRL and routes power to the C-Light instead
- High beam function continues to operate as normal
- OEM-size plug-and-play connectors for simple installation
- Embedded circuit protection for reliable long-term operation
- Assembled in St. Louis, Missouri by Diode Dynamics
Fitment
| Year Range | Make | Model | Compatibility Notes |
|---|---|---|---|
| 2015-2017 | Subaru | WRX and STi | Compatible with all trims |
| 2018-2021 | Subaru | WRX Base and Premium | Compatible, halogen projector headlights only |
| 2018-2021 | Subaru | WRX Limited | Not compatible, LED projector headlights |
| 2018-2021 | Subaru | STi (all trims) | Not compatible, LED projector headlights |
DD4055 is required for use with Diode Dynamics C-Light Switchback LED boards only. It is not compatible with OEM C-Lights, Morimoto C-Lights, Subaru Forester, or Subaru Levorg.
Specifications
| Detail | Value |
|---|---|
| Operating Voltage | 9-16V |
| Wire Size | 22 AWG |
| Operating Temperature | -40F to 185F |
| Connector Type | OEM-size plug and play |
| Shipped Weight | 0.17 lb |
| Warranty | 3 year replacement limited warranty |
What's Included
- One (1) DD4055 DRL harness module, controls both sides of the vehicle
About Diode Dynamics
Diode Dynamics designs and assembles its LED lighting products in St. Louis, Missouri. The company engineers its own components rather than reselling generic parts, with a focus on reliable circuit protection and OEM-grade connectors across its lighting and wiring accessories.
FAQ
What is the DD4055?It is a wiring harness that lets a compatible Diode Dynamics C-Light Switchback LED board also function as your Subaru's daytime running light, replacing the factory DRL signal with power to the C-Light.
Will my high beams still work normally after installing this harness?Yes. The harness only changes how the daytime running light is powered. High beam operation is unaffected and continues to function as designed from the factory.
Does this harness work with the factory C-Light or other LED brands?No. It is engineered specifically for Diode Dynamics C-Light Switchback LED boards and is not compatible with OEM C-Lights or Morimoto C-Lights.
Can I install this on a 2018 or newer WRX Limited or any STi?No. Those trims use newer LED projector headlights that are not compatible with this harness or with Diode Dynamics halos.
Does installation require cutting or splicing any factory wiring?No. The harness uses OEM-size plug-and-play connectors, so no cutting, splicing, or permanent modification is required.
How long does installation typically take?Most installers complete the plug-and-play installation in about 10 to 20 minutes using a basic non-marring trim tool.
Is this harness compatible with a Subaru Forester or Levorg?No. It is designed only for the specified Subaru WRX and STi model years and is not compatible with the Forester or Levorg.
What warranty coverage comes with this harness?It includes a 3 year replacement limited warranty covering manufacturing defects in the harness and its connectors.
Installation Instructions
- Confirm your Diode Dynamics C-Light Switchback LED boards are already installed and functioning.
- Locate the factory DRL and C-Light wiring near the headlight housing using a non-marring trim tool as needed for access.
- Disconnect the factory DRL connection and connect the DD4055 harness using the OEM-size plug-and-play connectors.
- Route the harness away from moving parts and secure it with existing factory clips or ties.
- Reconnect the battery if disconnected and test that the C-Light now activates as the daytime running light.
- Verify the high beam function still operates normally before closing up the headlight area.
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