HOSE AS 1048774 - Caterpillar

System Operation Description:Use this procedure under the following situation:The cooling fan J1/P1:11(Output 5) or the A/C high pressure switch J1/P1:41(Input 11) is suspected of incorrect operation.Note: Not all vehicle manufacturers, or all trucks for a manufacturer use the Caterpillar cooling fan circuit. Prior to troubleshooting, determine if the vehicle is using the ECM cooling fan circuit.Check the following items in order to determine if a vehicle is using the ECM cooling fan circuit:
The "Fan Control Type" parameter must be programmed to "On/Off PWM", "On/Off DC", "Three-Speed Fan PMW", or "Three-Speed Fan DC". The Caterpillar factory default is None.
A wire is present in the ECM connector J1/P1:11 (Output 5 (Cooling Fan Solenoid)). This occurs if an "On/Off" type of fan is used.
A wire is present in the vehicle harness connector J1/P1:11 (Output 5 (Slip Solenoid)). A wire is also present in the vehicle harness connector J1/P1:13 (Output 4 (Brake Solenoid)). This occurs if a three-speed fan is used.
Perform the special test for the "On/Off Cooling Fan" or the special tests for the "Three-Speed Fan". Access each menu in the order that follows: "Diagnostics", "Diagnostic Tests" and "Special Test". Activating and then deactivating the circuit will cause the air solenoid to click if the circuit is working properly.The following background information is related to this procedure:Cooling FanThe signal for the cooling fan is provided by the ECM in order to control the cooling fan. An input from one of the following items may cause the fan to turn on:
Dyno mode
Engine coolant temperature sensor
Intake manifold air temperature sensor
Engine retarder switches
PTO On/Off switch
OEM installed A/C high pressure switch
Manual fan override switchThe control unit for the A/C may be connected to the A/C high pressure switch J1/P1:41(Input 11) instead of a switch.The output for the cooling fan is intended to connect directly to the circuit for the cooling fan solenoid. The solenoid and clutch configuration must be selected in order for the ECM output to turn the fan "Off". The fan will remain on for a minimum of 30 seconds. The fan will not remain on for 30 seconds during engine start-up. The fan will not remain on for 30 seconds if the "A/C Pressure Switch Fan On Time" is programmed to 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 (600 to 750 rpm). The fan will be on continuously if the electrical circuit to the cooling fan air solenoid valve has an open circuit or if the ECM fan relay circuit is opened.Cooling Fan On Conditions (On/Off Fan)The ECM will turn on the cooling fan, if any of the following conditions are met:
With software prior to DEC03, the engine speed is less than 2250 rpm (2350 rpm on 2300 rpm ratings).
With DEC03 software, the engine speed is less than 2250 rpm.
The engine is not running.
The engine is cranking.
Dyno mode is active.
The engine coolant temperature is greater than 102 °C (216 °F).
There is an active