2015 4Runner Check Engine, TRAC OFF, 4LO light on

If it's like mine, it could be multiple items in the secondary air pump system. You can disconnect negative terminal and clear it first. I bought a Bluetooth scan tool to clear mine while I drive if it gets regular. I'm going to get a Hewitt delete kit for $450 and eliminate it. It's cheaper doing that than throwing expensive parts at a Toyota. It could be 4 or 5 different things and each one starts around $200+ each. They tell me replace catalytic converter, but I've never had to do that on a Toyota except stolen ones at the shop. They have the best.

 

The mechanic did you dirty, though it might be due to his unfamiliarity with the vehicle.

You have an active code pointing to a bad transmission range sensor aka neutral safety switch circuit that is mentioned previously in this thread. To shift into 4LO, the transmission needs to be in neutral. If neutral is not detected correctly, then 4LO doesn't work and you get the flashing caution light. Check the wiring going to the neutral safety switch. If wiring is OK, replace the switch. Being a 10 year-old New England truck, expect to chisel off the old switch in pieces...



The rough idle and loss of power steering is probably a bad serpentine belt. The belt drives the power steering pump and alternator. I would replace the belt first (~$50) before the other big ticket items. While the old belt is off, check all the idler pulleys including the one on the tensioner for roughness. The tensioner pulley is easy to replace; the whole tensioner is a much bigger job requiring the A/C compressor to be unbolted and moved aside.