mapj1:

It may be handled in the body of the trailing socket  if the lead is captive, and is so it saves a wire in that cable - all it is is a resistor to gnd whose value is switched  sets an upper limit to tell the car how much current it can draw, on a microswitch or a break early pin (S3 here), so the car charger has hopefully seen the resistance rise and stopped taking big amps, before the high current contacts are withdrawn.



EDITED to correct an erroneous  explanation


Regards Mike.

Can I get that on a coffee mug?

mapj1:

It may be handled in the body of the trailing socket  if the lead is captive, and is so it saves a wire in that cable - all it is is a resistor to gnd whose value is switched  sets an upper limit to tell the car how much current it can draw, on a microswitch or a break early pin (S3 here), so the car charger has hopefully seen the resistance rise and stopped taking big amps, before the high current contacts are withdrawn.



EDITED to correct an erroneous  explanation


Regards Mike.

Can I get that on a coffee mug?