1997 Isuzu NPR Tail Lights

First of all, I love this community. I have been a member for a short time, but I am glad I found it.

I am still a newbie, so please forgive me. I am trying to wire the tail lights on a 97 Isuzu NPR with a V8 5.7 350 engine. The issue I am having is that I have 1 wire that combines the turn signal and stop light and I am not sure how to split the signal as they are going to separate bulbs. I have a dedicated bulb for the turn signal, and a separate bulb for the brake lights.

The setup is the rectangular 3 lens fixture that has the reverse light(clear) , tail and brake light (red), and turn signal (amber).

Any advice will be greatly appreciated.

Thank you

brake light circuit and turn signal may have power available when you hit the switch maybe break light switch is out can you put up a schematic I imagine turn signal switch is on combination switch

Thank you for the reply chief eaglebear. I have attached the wiring diagram. I have highlighted in yellow the wires I am referring. From the stoplight switch, it goes into the flasher unit where it looks like it combines the turn signal and stoplight and comes out as 1 wire carrying both signals.

maybe check your grounds and then backprobe flasher unit while hitting switch and or brake to determine if flasher is working