Hey y'all, I tried searching but might not have searched the right way. I am having a weird issue with my driver side brake light on my 2016 4Runner. When I hit the brakes, all of the lights come on, but the driver side is significantly dimmer than the passenger side. When my headlights are on, the running lights work properly, and you can see the brake light get brighter, but just not as bright as the passenger side again.

So far, I've unplugged the connector to the light and checked that out - I see no issue with it so far. Plugged it back in, no fix.

I was unable to get the brake pedal connector off to check to see if there was anything wrong there, but I didn't have much time to mess with it at the time.

Any suggestions? Seems like it would either be a wiring issue or possibly a dud tail light? I did replace that specific tail with an OEM replacement from Amazon probably 3-4 years ago.

That kind of issue is usually a ground problem. Trace the ground wires to be sure they are good, especially where they might connect to the body and be corroded.

Edit: measure the voltage right at the bulb of the ground connection when the brakes are applied. It should be zero. If not, it is definitely a grounding issue.

I had an aftermarket one do that. It was the led module on that assembly

Remove both and swap sides to do a test and see if the issue follows the assembly with the issue.