Cooling Fan Output Operation with Fan Control Type Programmed to On-Off

17.1 Cooling Fan Output Operation with Fan Control Type Programmed to On-Off

Program Fan Control Type to On-Off to have the ECM provide control of an ON-OFF fan clutch. The Cooling Fan circuit sends out a high signal to turn the fan OFF. The fan comes ON in the event of an output circuit failure such as an open circuit. This requires a relay with normally open contacts (if powering the coil side of a relay), or a solenoid valve that deactivates the fan when it receives the disable (high) signal. Refer to “Wiring Diagram 34 -OnOff Cooling Fan Circuit” on page 78. Additional switching devices in the circuit should cause an open circuit to turn the fan ON. This circuit is designed to withstand a short circuit to “+Battery” voltage and will not be adversely affected if other devices are connected to this line when directly driving a solenoid. When driving a relay, connection of other devices to the Cooling Fan Output should not be necessary. OEM provided and installed components required: 1) Solenoid or Solenoid and Relay. Customer Parameter programming required: 1) Cooling Fan Type programmed to On-Off Fan.

NOTICE Caterpillar requires the OEM to install a warning sticker near the fan indicating the fan is automatically controlled and may come ON at any time.

Conditions to turn Fan ON for C-15 and C-16 Conditions to turn Fan ON for C-10 and C-12

The ECM will turn the cooling fan ON under any of the following conditions if engine rpm is less than 2250 rpm:

*These items are dependent upon programming of Customer Parameters. NOTE: The ECM will turn the cooling fan OFF for 10 seconds during an engine shutdown. The fan will remain on for a minimum of 30 seconds following ECM initiated activation except following engine start up, or if the A/C Pressure Switch Fan On Time is programmed less than 30 seconds. During engine start up, the ECM will keep the fan ON for 2 seconds after the engine has reached the programmed low idle (700 - 750 rpm). This is done because unstable vehicle battery voltage during cranking may cause the fan to cycle. The fan will be turned OFF by the control (after being turned ON) if engine rpm exceeds 2300 rpm or when all the following circumstances are met.

Engine Not Running Engine Not Running During Engine Cranking During Engine Cranking

Coolant Sensor Temperature > 216°F (102°C) Coolant Sensor Temperature > 205°F (96°C)

Active Coolant Temperature Sensor Diagnostic Active Coolant Temperature Sensor Diagnostic

Intake Manifold Air Temperature > 189°F (87°C) Intake Manifold Air Temperature > 189°F (87°C)

Intake Manifold Air Temperature > 162°F (72°C) with Boost Pressure > 10 psi (70 kPa) Intake Manifold Air Temperature > 162°F (72°C) with Boost Pressure > 10 psi (70 kPa)

*Engine Retarder ON in high mode > 2 seconds, when Fan With Engine Retarder in High Mode is programmed to YES *Engine Retarder ON in high mode > 2 seconds, when Fan With Engine Retarder in High Mode is programmed to YES

*A/C High Pressure Switch Input is Open or ECM is Counting *A/C High Pressure Switch Input is Open or ECM is Counting *PTO On/Off Switch in ON position, when PTO Activates Cooling Fan parameter is programmed to Continuous *PTO On/Off Switch in ON position, when PTO Activates Cooling Fan parameter is programmed to Continuous *Manual Fan Override Switch is ON, when the Fan Override Switch parameter is programmed to a selected input. *Manual Fan Override Switch is ON, when the Fan Override Switch parameter is programmed to a selected input.