Solve this mystery!

Current set up is OEM tails. The brake light on the driver's side of the car does not turn on/get brighter when the pedal is pressed. The bulb itself is not the issue and the passenger side brake light does turn on/get brighter when the pedal is pressed. The socket is not the issue as they have been interchanged and work when used on the passenger side. Ground wire is securely fastened.

Sounds like a wire issue, right? Here's what I find confusing... the DEPO and J's LED tails' brake lights worked just fine, but the OEM had a problem before and after the aftermarket tails were installed. So, why is the OEM the only tail having a problem?

 

Have you looked at night to see if there is even the slightest increase of light output?

EDIT alos consider that even if the ground is secure, is the wire itself damged in any way? The colored jacket might be hiding an issue.


Grab a multimeter and do a resistance check (ohms) and a continuity test

Multimeters should be in the hands of anyone working with a vehicle. it is a profoundly amazing diagnostic tool and can be bought for cheap

 

Thanks for the response. As a disclosure, I don't know electrical very well.

My buddy hooked up a meter (not sure what setting) and when we turned on the parking lights, the fuse for the "small light" as labeled by the box panel blew. This fuse covers parking lights, brake lights and license plate lights. Oddly, the radio was reset (even though it's not the same fuse, as I can see on the panel). The filament was already blown (new bulb as of today) for the high (brake pedal compressed) output. The low output filament also blew when the meter was connected.

I checked the wire jackets and they all looked good. Ground is also good. Then replaced the fuse and then put in a new bulb. Everything works now.

Doesn't make sense.