General Electrical System Check

GENERAL ELECTRICAL SYSTEM CHECK

A circuit consists of the power supply, switch, relay, load, ground, etc. There are various methods to check a circuit including an overall check, voltage check, short-circuit check, and continuity check. Each of the methods briefly described below applies only to circuits similar to the illustration.





1. VOLTAGE CHECK
(1) Ground one lead wire of the test light. If a voltmeter is used instead of the test light, ground the grounding side lead wire.
(2) Connect the other lead wire of the test light to the power side terminal of the switch connector. The test light should come on or the voltmeter should indicate a voltage.
(3) Then, connect the test light or voltmeter to the motor connector. The test light should not come on, or the voltmeter should indicate no voltage. When the switch is turned ON in this state, the test light should come on, or the voltmeter should indicate a voltage, with the motor starting to run.
(4) The circuit illustrated here is normal. If there is any problem, such as the motor failing to run, check voltages beginning at the connector nearest to the motor until the faulty part is identified.
2. SHORT-CIRCUIT CHECK
Because the fuse has blown, it is probable that there is a short circuit. Follow the procedures below to narrow down the short-circuit location.

STEP 1. Remove the blown fuse and connect the test light across the fuse terminals (Circuit switch: OFF).





Q. Does the test light illuminate?

YES Short-circuit exists between the fuse block and the switch. Repair the harness between the fuse block and the switch.

NO Go to Step 2.

STEP 2. Turn the switch ON and disconnect the illumination light connector.









Q. Does the test light illuminate?

YES Short-circuit exists between the switch and the connector. Repair the harness between the switch and the connector.

NO Short-circuit exists between the connector and the illumination light. Repair the harness between the connector and the illumination light.





3. CONTINUITY CHECK
(1) When the switch is in the "OFF" position and the contact points of terminals 1 and 2 are connected, the self-powered test light should illuminate or the ohmmeter should read 0 ohm.
(2) When the switch is the "ON" position and the contact points of terminals 3 and 4 are connected, the self-powered test light should come on or the ohmmeter should read 0 ohm.