FILM-IDENTIFICATION 3602142 - Caterpillar

open circuit is a failure of an electrical circuit that results in no flow of electrical current. An open circuit can be caused by several issues within the circuit. An open circuit is caused by a poor connection, broken wire, or a failed connection in one of the electrical connectors used in a circuit. A normally closed circuit will have less than 5 of resistance.Reference: For a complete electrical schematic, refer to the Electrical System Schematic for the machine that is being serviced.The following procedure is a way to check for an open or a poor connection in a circuit.TEST FOR AN OPEN CIRCUIT.
Identify the connectors and the wire numbers of the suspect circuits. Use the Electrical System Schematic of the machine to identify the circuits.
Turn the key start switch and the disconnect switch to the OFF position.
Disconnect the component and the ECM or ECU from the wiring harness.
At one of the disconnected harness connections, place a jumper wire from the contact of the suspect wire to frame ground.
At the other connector of the machine harness, use the multimeter probes to measure the resistance from the contact of the suspect wire to frame ground.Expected Result: The resistance is less than 5 ohms.OK - The resistance is less than 5 ohms. The harness circuit is correct.Stop.NOT OK - The resistance is greater than 5000 ohms. There is an open in the machine harness.Repair: Repair the machine harness or replace the machine harness.Stop.