Direct form etrailer dot com. Note it's for a 96. A 97 is likely the same or very close.
Your 1996 Isuzu NPR will need to have a trailer wiring harness and brake controller hardwired in. If the truck has the turn signals and brake lights on the same bulbs then the first thing you will need is a 4-Way, # 18252
. If the truck has turn signals and brake lights on separate bulbs then use # 119178KIT
Then to add a 7-Way and the provisions to install a brake controller you will need installation kit # ETBC7
. I have included some links that show and explain the ETBC7 installation. For a brake controller I recommend the P2 # 90885
because it is easy to set up and use and it is reliable.
On the brake controller the black wire is 12 volt power, blue is output to the trailer brakes, white is ground, and red is input from the stop light switch. If your NPR has air brakes you may not have the proper signal for the red wire under the dash.
Check to see if there is a brake switch above the brake pedal. If there is you would use the circuit tester included with ETBC7 to test the wires. If you find one that has power only when the brake pedal is pressed then you are good to go. If you can't find one you will need to tap into the stop light or CHMSL (center high mount stop light) fuse for the red wire (as long as the stop light or CHMSL is the only thing fused on that circuit.