THERMOSTAT AS 3788437 - Caterpillar

Test For An Open Circuit
Table 1
Troubleshooting Test Steps Values Results
1. Identify Open 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 switch and the disconnect switch OFF.
C. Disconnect the component and the ECM from the wiring harness.
D. At one of the disconnected harness connections, place a jumper wire from the contact of the suspect wire to frame ground.
E. At the other connector of the machine harness, use the multimeter probes to measure the resistance. Measure the resistance from the contact of the suspect wire to frame ground.
The resistance is less than 5 Ω. OK - The harness circuit is correct.
STOP.
NOT OK - The resistance is greater than 5K Ω. There is an open in the machine harness.
REPAIR: Repair or replace the machine harness.
A resistance that is greater than 5 Ω but less than 5K Ω would indicate a loose connection or a corroded connection in the circuit. A resistance measurement that is greater than 5K Ω would indicate an open in the circuit.
STOP.