Wiring Harness (Short Circuit) - Test
A short circuit is a failure of an electrical circuit that results in undesired electrical current. Usually, a short circuit is a bypass of the circuit across a load. For example, a short across the wires in a circuit for a lamp produces too much current in the wires, but no current is felt at the lamp. The lamp is shorted out. The resistance in a normal circuit is greater than 5 ohms. The following procedure explains the test for a short circuit:
ReferenceFor a complete electrical schematic, refer to Electrical System Schematic.
TEST FOR A SHORT CIRCUIT.
- Identify the connectors and the wire numbers of the suspect circuits. Use the systems electrical schematic to identify the circuits.
- Disconnect power from the system to be tested.
- Disconnect the wiring harness at both ends of the suspect circuit.
- At one end of the wiring harness, place one of the multimeter probes on the contact of the suspect wire.
- Use the other multimeter probe to check the resistance across all other contacts in the connector and ground.
Expected Result: The resistance is greater than 5 ohms for all the measurements.
YES - The resistance is greater than 5 ohms for all the measurements. The harness circuits are correct.
Stop.
NO - The resistance is less than 5 ohms. There is a short in the machine harness. The short is between the suspected wire and the wire with the lowest resistance measurement.
Repair: Repair the wiring harness or replace the wiring harness.
Stop.
Caterpillar Information System:
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