Precautions In Trouble Diagnosis And Repair Of Electric Parts

The battery cable must be disconnected from battery's (-) terminal, and the ignition switch must be set to OFF position, unless otherwise required by the diagnostics.
Securely fasten the wiring harness with clamps and slips so that the harness does not interfere with body end parts or edges and bolts or screws.
When installing the parts, be careful not to catch them on the wiring harness.
When disconnecting a connector, do not pull the wires, but pull while holding the connector body.

Fig 1: Precaution For Disconnecting Connector
Courtesy of SUBARU OF AMERICA, INC.
Some connectors are provided with a lock. One type of such a connector is disconnected by pushing the lock, and the other, by moving the lock up. In either type the lock shape must be identified before attempting to disconnect the connector.
To connect, insert the connector until it snaps and confirm that it is tightly connected.

Fig 2: Example Of Disconnecting Connector
Courtesy of SUBARU OF AMERICA, INC.
When checking continuity between connector terminals, or measuring the voltage across the terminal and ground, always contact tester probe(s) on terminals from the wiring connection side. If the probe is too thick to gain access to the terminal, use "mini" test leads.
To check water-proof connectors (which are not accessible from the wiring side), contact test probes on the terminal side being careful not to bend or damage terminals.

Fig 3: Checking Continuity Between Connector Terminals
Courtesy of SUBARU OF AMERICA, INC.
Sensors, relays, electrical unit, etc., are sensitive to strong impacts.
Handle them with care so that they are not dropped or mishandled.