Connect an electronic service tool to the vehicle’s data link.
Turn the keyswitch to the ON position.
Monitor the coolant temperature with the electronic service tool.
If equipped with an in-dash coolant temperature gauge, monitor coolant temperature with an electronic service
tool and compare the cab temperature gauge reading.
Replace the cab temperature gauge if it is not within the manufacturer’s specifications of the correct reading.
If the manufacturer’s specifications are not available, replace the gauge if it is not within ± 3.9°C or ± 7°F of
the correct reading.
For vehicles equipped with temperature controlled shutters, check the coolant temperature at which the
shutters open and close. Compare this value to what is stamped on the shutter control.
Cummins Inc. recommends that the shutters open at 85° C [185°F] engine coolant temperature.
If equipped with a temperature controlled cooling fan clutch, check the coolant temperature at which the fan
clutch engages.
If the fan clutch engagement is controlled by a fan control on the vehicle, compare the recorded value to what is
stamped on the fan control and/or reference the OEM service manual.
If the fan clutch engagement is controlled by the engine’s electronic control module (ECM), the engagement coolant
temperature is a set value that can not be changed. If the fan clutch does not engage, check to make sure the fan
control logic parameter is set correctly.
The ECM is capable of using either a zero (“0”) VDC or system voltage signal to engage the fan clutch. The exact
enable logic can be selected in the Features and Parameters section of INSITE 1111 electronic service tool.
Cummins Inc. recommends that the fan engage at 96°C [205°F] engine coolant temperature.
If equipped with a viscous fan drive, check the coolant temperature at which the fan engages. Viscous fan
clutches are typically activated by a built-in sensor behind the radiator that monitors air temperature.
NOTE: Some viscous fan drives can be electronically controlled.
When the air temperature reaches a specific level, depending on the temperature setting of the sensor used,
the temperature-sensing control moves an actuator that allows viscous fluid to engage the fan drive and increase
the fan speed. For more information, refer to the OEM service manual.
Cummins Inc. recommends that the fan engage at 96°C [205°F) engine coolant temperature.
