The whistle is in the engine car, I have a Lionel no.60 whistle controller.
The whistle blows if I take the train off the tracks and touch a wire to the wheel and a wire to the electric pickups on the bottom of the motor. It will not blow when the car is on the tracks whether e car is moving...
This is a prewar item so directions are scarce. I pulled the cover off to check the connections.
The two left terminals are connected to the transformer.
The two right terminals are connected to the track
The two center terminals are common
The left terminal is connected to the A terminal