1. Precautions for electrical test
(1) Be sure to turn the key switch to the OFF position before disconnecting or connecting the connector.
(2) Do not pull the wire to disconnect the connector, hold the connector and pull it apart.
(3) Most connectors are made of brass. Before connecting the connector, check that the connector terminals are straight and that the terminals are not damaged or rusty.
(4) Before using the circuit tester, refer to the instructions in the circuit tester manual. Then, adjust the circuit tester to meet the measurement voltage range and current polarity.
(5) Before connecting the connector test, always check the connector terminal number, see the circuit diagram.
When the size of the connector is very small, the standard probe is used for the test, and the size is too large. At this time, a thin section of polished wire or needle can be wrapped around the probe to make the test easier.
2. Three basic forms of wire inspection
(1) Use an ohmmeter to measure the resistance of the circuit tester and check the continuity of the circuit.
(2) Use a voltmeter to measure the voltage of the circuit tester and check whether the voltage in the circuit meets the regulations.
(3) Check the controller function by giving a false signal instead of the sensor signal. To do this, short the connector and send its voltage directly to the controller.
3. Continuity check
(1) Single-line continuity check. Disconnect the connectors at both ends of the wire, and check the continuity at both ends: the ohmmeter reading is 0Q-continuous; the ohmmeter reading is ∞-discontinuous.
Note: When the connector at one end is far away from the other end, use a cable clamp to connect the-end of the connector (A) to the frame of the machine, and then, check the continuity of the wires passing through the machine frame, as shown in Figure 5-62 As shown. The ohmmeter reading is 0n--continuous; the ohmmeter reading is ∞-discontinuous.
(2) Single-line short circuit check. Disconnect the connectors at both ends of the wire and check the continuity between the wire-end connector and the machine frame. The ohmmeter reading is 00-there is a short circuit phenomenon; the ohmmeter reading is ∞-there is no short circuit phenomenon.
(3) Multi-line continuity check. Disconnect the connectors at both ends of the wire, and short-circuit the two terminals A and B at one end of the connector, as shown in Figure 5-62. Then, check the continuity between the terminals a and b of the connector. If the ohmmeter reading is ∞,
The line A-a or B-b is discontinuous. To find out which line is not continuous, perform a single-line continuity check on the two lines, or change the short-circuit terminals from A and B to A and c, and then check the secondary terminal a and. Continuity between.
Note: Through two multi-line continuity checks, you can find out which line is not continuous. Short circuit between terminals A and e, and check the continuity between terminals a and c. The ohmmeter reading is discontinuous between 00-line B-b; the ohmmeter reading is discontinuous between ∞ line A-a.
(4) Multi-line short circuit check. Disconnect the connectors at both ends of the wire, and check the continuity between terminals A and B or C. The ohmmeter reading is 0N, there is a short circuit between the two terminals; the ohmmeter reading is ∞--there is no short circuit between the two terminals.
Note: For connectors, circuit diagrams and wiring diagrams, see the electrical system section.
