Strange electrical issue

Hello,

I'm having a strange issue with my taillights on my 2003 double cab 4x4 3.4l.

When I press the brake with my left turn signal on, it will begin flashing rapidly (as if there was a dead bulb). But, when i take my foot off the brake, it flashes normal again. This does not happen with my right turn signal.

After some searching I'm guessing these issues have something to do with the towing module installed underneath the driverside taillight.

I'm not great with electrical, so I'm wondering if anyone can advise my next steps.
It's a toyota module but it doesnt look like it was factory installed.
Should i just scrap the module and solder the taillight connections right to the wires coming from the front? I don't tow much, and i don't want to rule it out for the future, but if these modules are tricky to fix i might just say forget it.

My ABS light also comes on when I shift into reverse (A/T), could this be related to a bad towing module as well?

 

The module might be the problem. I would swap out the left rear tail/brake light bulb (I assume the truck uses a dual element bulb) to see if the fixes the first problem.

If the Toyota module connects the same way the aftermarket modules do (I don't know), you can disconnect the module and reconnect the tail light connector and determine if the module is at fault.

 

Turns out the ground wire to the taillight broke. Connected it back together and everything seems to be good. ABS light stopped coming on in reverse as well.
Thankfully a pretty easy fix

 

I keep relearning it is best to check the simple things first. Good job.

 

Sounds like you are learning electrical! Number one thing always check for power then ground.Grab a cheap multimeter from harbor height most have a booklet with it.And ps A/C house and DC auto are a lot different.Never stop learning!!!