There is four-wire (4-wire) scheme implemented to take the precise measurement of low resistance with AM-6000 and to escape the affect of stray resistance and the measurement leads resistance.
On every measurement sub-range they use its own test current Is which flows from T2 to T1 terminal. The same current flows through the resistance under measurement R (resistor). AM-6000 measures voltage Vx on P1 and P2 terminals which equals as follows:
Vx=Is * Rx
In accordance with Vx value the device automatically counts the value of the unknown resistance Rx.
Rx=Vx/Is
Thus the stray resistance of the measurement leads doesn't affect the measured resistance between P1 and P2 terminals.
To measure the resistor resistance it’s necessary to connect the clamps of the measurement leads to the resistance under test (like it’s shown in Pic. 1) and to measure the resistance of the circuit section on a board you need to connect the clamps the way it’s shown in Pic. 2.
