JBL System in a Non JBL truck

I purchased a JBL premium head unit with HD, XM, Nav, etc, from a 2019 Taco. I have a 2017 "SR" with the stock Entune unit. With existing wiring, the unit sounds great, and I can select stations or change the mode from the steering wheel; but the volume control on the steering wheel or manual knob does not work. I am assuming it is because I don't have the JBL amp in place. Until I can afford the JBL amp, is these something I can do in the meantime? Wiring plug ends may be an issue also.
Also, what are the names of the big salvage yards in the U.S. that have newer wrecked Tacoma
Trucks ?

 

I don't know much about such things. But I recently put a new head unit into a maxda mx5 from an outfit in Albuquerque called paradise audio. It was a bose system and also had controls on the wheel. They were still able to use the existing bose amp inside but I had to purchase a specialized wiring harness which in itself cost over 200 dollars. Without that the controls would not have worked. Good luck.