Disconnect the connectors at both ECU and sensor sides.
Measure the resistance between the applicable terminals of the connectors. Resistance: 1 Ω or less
Measure the resistance while lightly shaking the wire harness vertically and horizontally.
When tester probes are inserted into a connector, insert the probes from the back. For waterproof connectors in which the probes cannot be inserted from the back, be careful not to bend the terminals when inserting the tester probes.
This guide is based on the book edition Toyota (RM502U, 1997)