Don't you actually read posts? This is an LED module. There is no "filament". There are 6 wire positions.Thats incorrect, if the ground is bad with a dual filament bulb it can get enough ground to run the lower current tail light filament by grounding through the larger filament (brake t/s) by feeding from the other light.
He needs to verify which one is actually the ground and trace it to where it is supposed to be grounded. Remove the bulb and inspect the socket for corrosion. Check connections on the BCM and down line. Do all this without the new led unit because the lower current draw from that unit may cause the BCM to not recognize it. Solve in standard configuration so additional conditions are not created.
RIGHT REAR LAMP ASSEMBLY - BLACK 6 WAY
|L62 18WT/BR (EXCEPT EXPORT)||RIGHT REAR TURN SIGNAL DRIVER|
|Z362 18BK/BR (EXPORT)||GROUND|
|L62 18WT/BR (EXPORT)||RIGHT REAR TURN SIGNAL DRIVER|
|L50 18WT/TN (DIESEL)||PRIMARY BRAKE SWITCH SIGNAL|
|L78 18WT/OR (EXCEPT EXPORT/EXCEPT TRAILER TOW)||FUSED PARK LAMP RELAY OUTPUT (RIGHT)|
|L50 18WT/TN (GAS EXPORT)||BRAKE LAMP SWITCH OUTPUT|
|L78 18WT/TN (TRAILER TOW)||FUSED PARK LAMP RELAY OUTPUT (RIGHT)|
|L1 18WT/LG (EXCEPT TRAILER TOW)||BACK-UP LAMP FEED|
|L1 18 WT/PK (TRAILER TOW)||BACK-UP LAMP FEED|
|Z362 18BK/BR (EXCEPT EXPORT/EXCEPT TRAILER TOW)||GROUND|
|L38 20WT/YL (EXPORT)||REAR FOG LAMP SWITCH OUTPUT|
|Z362 18BR/OR (TRAILER TOW)||GROUND|
|L78 18WT/OR (EXPORT)||FUSED PARK LAMP RELAY OUTPUT (RIGHT)|