WINDOW-TOP 4287920 - Caterpillar

Test for a Short 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 from the wiring harness.
At the machine harness connector for the ECM, place one of the multimeter probes on the contact of the suspect circuit wire.
Use the other multimeter probe to check the resistance between the suspect circuit wire and frame ground. Also check all the other contacts that are used in the ECM connectors.
As each measurement is made, observe the multimeter resistance measurement and wiggle the machine harness connectors for the ECM. Gently pull on the wires and move the wires around.
While observing the multimeter resistance measurement, wiggle the machine harness and the harness connectors that are involved in the circuit. Gently pull on the wires and move the wires around.Expected Result: The resistance measurement is greater than 5000 ohms for each of the measurements.OK - The resistance is greater than 5000 ohms for all the measurements. An obvious short is not evident. An intermittent short circuit could still be causing a problem.NOT OK - One or more of the resistance measurements is less than 5 ohms. There is a short in the machine harness. The short is between the suspected circuit wire and the circuit wire with the lowest resistance measurement. The short could also be between the suspected circuit wire and the machine frame ground.Isolating the location of the Short Circuit
Once it has been determined that a short circuit is present, the location of the short in the circuit must be found and repaired.Use the troubleshooting procedure for the specific diagnostic code that is activated in order to isolate whether the problem is caused by a system component or is present in the machine wiring harness.When the machine wiring harness is suspected, examine the circuit on the full Machine Electrical System Schematic. Starting at the ECM, identify, and locate each machine harness connector that is involved in the circuit. Starting at the ECM, one at a time, disconnect each connector. Inspect the pins and the sockets on the male connector and on the female connector. Verify that all the contacts are securely installed in the connector body. Ensure that the contacts are clean and the contacts are in good condition.While each of the connectors is disconnected, use a digital multimeter to measure the resistance between either frame ground or measure the resistance between the suspect circuit wire and the circuit wire with the low-resistance measurement. While observing the measurement, wiggle the connector and the machine harness to check for intermittent short circuits. Do this as you move outward from the ECM to isolate the section of the harness where the short circuit is occurring.Reconnect the connector. Ensure that the locking clips on the connectors are engaged. Check all the connectors that are in the suspect circuit in this manner. After the connectors