Get a 4Runner maintenance manual. Look at how the car is wired, and what modules are in the car. That'll probably give you enough hints to figure it out. If

Get a 4Runner maintenance manual. Look at how the car is wired, and what modules are in the car. That'll probably give you enough hints to figure it out. If not, and you're the owner of the car, start poking around electronics to find out what chips are in them. Look up data sheets. Or try to sniff signals off data lines and see if they look like CAN signals.