TUBE AS-FUEL 3378006 - Caterpillar

Circuit Voltage Test By Use Of Meter
1 Use this test to find the voltage present at a specific test point on the machine. Use the correct battery lead wire to connect the meter ground (-) terminal to a good ground on the machine frame. Use the correct test harness to connect the machine wiring harness test point to the connector on the tester.2 Turn the selector switch and read the circuit voltage on the meter. The ground switch (lamp control) can be either ON or OFF for this test. If the ground switch is ON, the lamps connected to the active circuits will light. Resistance in an electrical circuit (caused by wire size and/or length, connectors and/or corrosion) will decrease current (voltage) flow. The meaning of this is, that the farther away from the machine power source (batteries) a test is made, the smaller the voltage reading will be on the meter.On many machines there is a minimum amount of voltage that is needed to activate some of the components in the electrical system. As an example, the shift synchronizing solenoids used on Caterpillar off-highway trucks and tandem-powered tractor-scrapers will not activate with less than 20 VDC. This test can be used to find the cause of an electrical circuit problem if a solenoid that is known to be good will not operate because there is too much voltage loss in the circuit that controls the solenoid.Harness Continuity Test
1 In a test of a harness for continuity, both ends of the harness are disconnected. A ground adapter is connected to one end of the harness. The ground adapter comes to all of the wires in the harness to machine ground. Connect