determining whether tail light on 2018 Tab 320 is defective

jalars8

Left turn signal/brake light on my 2018 Tab 320S is not working but the left tail light does work.  Does this tell me the LED unit is bad and needs to be replaced?  I replaced the 7 pin cable because the old one was very corroded.  My plug tester shows there is output from tow vehicle for the left signal/brake light.  

MuttonChops

Since you have replaced the 7-Pin Cable suggest you start by re-checking the trailer Junction Box Wiring . . . did you get the 7-pin wires back on the correct terminal posts and are the trailer side wires connected/correct.

The LED tail light units do have two banks of LEDs, one bank lights for the tail light and both light for the Stop/Turn.

jalars8

I was meticulous in getting the 7 pin wiring correct when installing the new cable and have double checked it.  Not sure what you are referring to when you mention trailer side wires.  Assuming I did get the 7 pin cable wiring right, wouldn't the fact that the left turn/brake light is not working but the tail light is working indicate the LED unit is defective?

jalars8

The problem with left turn/brake light existed before I replaced the cable.   I thought replacing the cable would fix the problem.

MuttonChops

Good to know Stop/Turn was defective before 7-Pin cable change.

"Trailer Side Wires" is in reference to the Junction Box Wires that are not part of the 7-Pin Cable.  It is possible while changing the 7-Pin Cable wires to pop off a Trailer Side wire from the Junction Box terminal screws.

Your tail light unit might have failed.  There are no user replaceable parts in the tail light unit one possible replacement unit is:

   An Amazon Tail Light Source

You could also use the Forum Search Function to review other owner tail light failure actions.

jalars8

Thanks Muttonchops.  I appreciate your help.  I did maintain all the various wires in correct position in the junction box- took a photo of the junction box before I started the project.  The tail light body in my Tab seems to be thoroughly "glued" onto the inside of the tail light/reflector housing with what looks like silicone caulk so I will have to figure out how to deal with that so that I can replace the tail light, or - in another thread on the forum, someone said they were able to  replace just the LED unit and not the whole tail light body by removing the red lens and popping out the LED unit, do the wire connections for the new LED unit and popping it in.  I may consider that alternative.