CAGE 0990235 - Caterpillar

Fan Control
Illustration 1 g01232914
Power Distribution
The engine ECM circuit breaker transfers power to terminal "J1-48" and terminal "J1-52" of the engine ECM when the electrical disconnect switch is in the ON position. The engine ECM is grounded at terminal "J1-61" and terminal "J1-63".When the main power relay is energized, circuit breaker "CB1" transfers power to terminal 1 and terminal "7" of the CMS connector. Circuit breaker "CB1" also transfers power to the "A" contact of the hydraulic oil temperature sensor. The CMS is grounded at terminal "2".Input Components
The engine ECM monitors the engine coolant temperature and the engine ECM monitors the intake air temperature. The CMS monitors the hydraulic oil temperature. The CMS passes the hydraulic oil temperature information to the engine ECM through the Cat Data Link lines.Fan Control
In order to control the fan, the engine ECM analyzes the following:
Coolant temperature input
Intake air temperature input
Hydraulic oil temperature inputBased on this analysis, the engine ECM generates an output signal of between 85 mA and 105 mA from terminal "J1-51". This signal is sent to the cooling fan solenoid. The fan speed is inversely proportional to the strength of the output signal.