Blower Motor Circuit Question

[RustyPile]

A diode is simply an electrical check valve.. It will pass current in one direction and block it in the other. A "diode tester" DVM is not necessary.. Set the resistor testing mode to 1K ohm- 10K ohm.. Like most electronic components, a diode cannot be tested while it's in the circuit, so disconnect one lead. Connect the meter leads to the diode leads. Make note of the reading, then reverse the leads and take another reading.. One reading should be high resistance, and the other reading should be low resistance.. If the diode is shorted, it will test low resistance on both readings.. If it's open or partially open, it will read high resistance on both readings.