THUMB AS 4400642 - Caterpillar

Test For A Short Circuit
Table 1
Troubleshooting Test Steps Values Results
1. Identify Short Circuit.
A. Identify the connectors and the wire numbers of the suspect circuits. Use the Electrical System Schematic of the machine to identify the circuits.
B. Turn the key start switch and the disconnect switch to OFF.
C. Disconnect the component and the ECM from the wiring harness.
D. At the machine harness connector for the ECM, place one of the multimeter probes on the contact of the suspect wire.
E. Use the other multimeter probe to check the resistance across all other contacts in the connectors of the ECM and frame ground.
The resistance is greater than 5K Ω for all the readings. OK: The harness circuits are correct.
STOP.
NOT OK: The resistance is less than 5 Ω. 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 or replace the machine harness.
Note: A resistance that is greater than 5 Ω but less than 5K Ω indicates a loose connection or a corroded connection in the circuit. A resistance measurement that is greater than 5K Ω indicates an open in the circuit.
STOP.