- Engine:
- C7 (S/N: C7S1-UP)
- C9 (S/N: MFF1-UP; C9S1-UP)
- C13 (S/N: LEE1-UP)
- C15 (S/N: SDP1-UP; B5R1-UP)
- C9 (S/N: MFF1-UP; C9S1-UP)
Introduction
There have been complaints that the engine cooling fan is cycling intermittently. The solution below gives the conditions for the activation and deactivation of the engine cooling fan. Also, a comparison is made in order to establish that the fan is cycling properly.
Problem
There have been several complaints from the field that the engine cooling fan is cycling intermittently.
Solution
Use the following lists of conditions in order to establish the cause of the cycling of the engine cooling fan.
The Engine Control Module (ECM) will turn the cooling fan ON under any of the following conditions if engine rpm is less than 2,250 revolutions per minute:
- The engine is not running.
- The engine is cranking.
- The temperature of the engine coolant is greater than 102° C (216° F).
- There is an active diagnostic for the coolant temperature sensor.
- The temperature of the intake manifold air is greater than 87° C (189° F).
- The temperature of the intake manifold air is greater than 72° C (162° F) and boost pressure is greater than 70 kPa (10 psi).
- There is a J1939 request from the transmission.
- The "Engine Retarder ON" is in high mode for more than two seconds and the "Fan With Engine Retarder in High Mode" is programmed to "YES".
- The input for the high pressure switch on the air conditioning system is open or the ECM is counting.
- The on/off switch for the PTO is in the ON position and the "PTO Activates Cooling Fan" parameter is programmed to "Continuous".
- The switch for the manual fan override is ON and the "Fan Override Switch" parameter is programmed to a selected input.
- The "Aftertreatment Regeneration Device Fan Enable Vehicle Speed Threshold" is met.
Note: The last five items that are located above are dependent upon programming of the "Customer Parameters".
Note: The ECM will turn the cooling fan OFF for ten seconds during an engine shutdown.
The fan will remain on for a minimum of 30 seconds following activation from the ECM except following engine start-up. Also, the fan will stay on if the "A/C Pressure Switch Fan On Time" is programmed for less than 30 seconds. During engine start-up, the ECM will keep the fan ON for two seconds after the engine has reached the programmed low idle. The low idle is programmed between 600 and 750 revolutions per minute. This is done because unstable battery voltage during cranking may cause the fan to cycle.
The fan will be turned OFF by the control if the engine rpm exceeds 2,300 revolutions per minute or if any of the following circumstances are met:
- The temperature of the engine coolant is less than 102° C (216° F).
- The fan has been on for at least 30 seconds.
- The temperature of the intake manifold air is less than 65° C (149° F).
- The "Engine Retarder ON Strategy" is not active.
- The high pressure switch for the air conditioning is not active.
- The PTO On/Off Switch is in the OFF position.
- The Manual Fan Override Switch is in the OFF position.
- There is a J1939 request from the transmission in order to disable the fan.
- Vehicle speed is greater than the "Aftertreatment Regeneration Device Fan Enable Vehicle Speed Threshold".
- Engine speed is present with the ignition switch in the OFF position.
Note: The ECM will turn the cooling fan OFF for ten seconds during an engine shutdown.
Use the recorder function in Caterpillar Electronic Technician (ET) an create a data log in order to determine if the fan is operating correctly.
Set up a data log with a sample rate of 240 samples per minute. The duration must be set for more than 60 seconds. Create a new group that contains the following channels:
- A/C Fan Input
- A/C High Pressure Fan Switch
- A/C High Pressure Switch
- ARD Fan Enable Vehicle Speed Threshold
- Boost Pressure
- Cooling Fan
- Engine Coolant Temperature
- Engine Retarder
- Engine Speed Fan Override Switch Fan Speed
- Intake Manifold Air Temperature
- On/Off Fan Output
- PTO On/Off Switch
- Transmission Requested Percent Fan Speed
Compare the results of the data log to the conditions that are listed above for the activation and deactivation of the engine cooling fan. This comparison will establish if the engine cooling fan is cycling properly or if there is another issue that needs to be investigated further.