Precautions for Electrical Circuit Service

When replacing a fuse, make sure to use a fuse of the specified capacity. Use of a fuse with a larger capacity will cause damage to the electrical parts and a fire.
When disconnecting and connecting coupler, make sure to turn ignition switch OFF, or electronic parts may get damaged.
When disconnecting connectors, never pull the wiring harnesses. Unlock the connector lock first and then pull them apart by holding connectors themselves.
When connecting connectors, also hold connectors and put them together until they lock securely (a click is heard).
When installing the wiring harness, fix it with clamps so that no slack is left.
When installing vehicle parts, be careful so that the wiring harness is not interfered with or caught by any other part.
To avoid damage to the harness, protect its part which may contact against a part forming a sharp angle by winding tape or the like around it.
Be careful not to touch the electrical terminals of parts which use microcomputers (e.g. electronic control unit like as ECM, PCM, P/S controller, etc.). The static electricity from your body can damage these parts.
Never connect any tester (voltmeter, ohmmeter, or whatever) to electronic control unit when its coupler is disconnected. Attempt to do it may cause damage to it.
Never connect an ohmmeter to electronic control unit with its coupler disconnected. Attempt to do it may cause damage to electronic control unit sensors.
Be sure to use a specified voltmeter/ohmmeter. Otherwise, accurate measurements may not be obtained or personal injury may result. If not specified, use a voltmeter with high impedance (M Ω/V minimum) or a digital type voltmeter.
When taking measurements at electrical connectors using a tester probe, be sure to insert the probe from the wire harness side (backside) of the connector.
When connecting meter probe from terminal side of coupler because it can't be connected from harness side, use extra care not to bend male terminal of coupler or force its female terminal open for connection. In case of such coupler, probe to avoid opening female terminal. Never connect probe where male terminal is supposed to fit.
When checking connection of terminals, check its male half for bend and female half for excessive opening and both for locking (looseness), corrosion, dust, etc.
Before measuring voltage at each terminal, check to make sure that battery voltage is 11 V or higher. Such terminal voltage check at low battery voltage will lead to erroneous diagnosis.