Support / ONYX RCR Weak Brake Light Fix

Credit: Ross Krasnow

ONYX RCR Weak Brake Light Fix

If your stock brake light appears dim and unimpressive, it’s likely due to an improper factory connection. You may notice that it’s significantly weaker compared to the DRL (Daytime Running Light). To confirm this issue, grab a multimeter and check the voltage being supplied to the brake light. Chances are, you’ll find that it’s only receiving 10V instead of the full 12V that powers the DRL, resulting in its subpar performance.

The Issue

The Kelly controller manual explains that the brake/motor stop switch requires a 12V signal connected to Pin 25 (yellow wire). This 12V source can either:

Come directly from the controller (Pin 11, red wire).
Be supplied by an external source, such as a 12V buck-boost converter (recommended).

The problem? The 12V signal from the controller is insufficient for powering lights properly, leading to a dim brake light. Fortunately, the ONYX RCR already includes a 12V buck-boost converter used to power the DRL, turn signals, and other components, which provides a much more reliable 12V source.

Diagnosing the Problem

Tracing the wires confirmed the issue:

Pin 25 (yellow wire) connects to a white wire in the harness.
Pin 11 (red 12V wire) connects to a green wire in the harness.

These wires ultimately connect to the brake light switch, but this setup is far from ideal and causes the weak brake light issue.

The Fix

This is an easy fix that makes a noticeable difference:

Locate the Brake Switch Connection:

Find where the brake switch plugs into the wiring harness.
De-Pin the Green Wire:
Remove the green wire carrying the inadequate 12V signal from the controller.
Replace with a Proper 12V Line:
Connect a 12V line from the buck-boost converter to replace the green wire in the harness.

Results

Once this adjustment is made, your brake light will shine significantly brighter, powered by a steady and reliable 12V source-just as it should have been from the beginning. Interestingly, some ONYX RCR models already feature a brighter brake light due to an updated version of the main wiring harness, which incorporates a revised connection setup.

Final Thoughts

If your stock brake light is underperforming, don’t settle for mediocrity. With this straightforward fix, you can restore your brake light to its full potential, ensuring it works as it was meant to. Take a few minutes to make this upgrade, and enjoy a safer, brighter, and more visible ride!