My problem is very simple. I currently don't have any idea on how I will add a LED in that circuit so that whenever a load is connected (of course Vin must be connected to the outlet), the LED will light up. I doubt if I will just put it in series with the load. Just tell me the nodes to connect and if additional resistors are needed. Or maybe just provide me a link which has a similar circuit but with a LED. Thanks.
Inside of a high-side switch, this is a high-side sensing circuit.
To turn on a transistor, you need about a minimum of 0.7v, b to e. 5A at 0.7v is 0.14Ω and dissipates ~4w. Put this current sensing resistor in series with the reg. IC input line.
This resistor needs to be adjustable; I'd make this resistor out of about 1' of #30 wire wrap wire.
Hook up a PNP transistor with the e terminal upstream of this resistor and b terminal downstream. Put a 1kΩ resistor in series with the base lead.
Run the collector lead through a 40/.02 = 2kΩ resistor through your LED to ground.
The breakdown voltage of this transistor needs to be >40v.
If you need a snap-action turn-on for the LED, or if you need the LED to turn on at very low load currents, this circuit will get more complicated.