HOSE 2526304 - Caterpillar

Fan Relay For The Rear Differential ("HI and LO")
Illustration 1 g00510127
Fan relay for the rear differential - (S/N: CBR1-UP) (S/N: 1HW1-UP) (S/N: 2BW1-258) (S/N: APX1-450) (S/N: ATY1-UP) (S/N: 2PZ1-105) (S/N: 4GZ1-UP) (S/N: 5AZ1-399)
The fan relays are outputs of the brake ECM. The fan relays are designed to energize the HI rear differential fan and the LO rear differential fan. When the fan relay is activated the relay receives + battery voltage from the ECM.Note: The ECM monitors the relay circuit for shorts to ground. A diagnostic code will be displayed. Refer to the troubleshooting section of this manual for the active diagnostic codes.Note: The fan relays are optional. The relays may not be available on all trucks.Relay - Rear Differential Fan
Illustration 2 g01100463
Relay - rear differential fan - (S/N: 2BW659-UP) (S/N: APX451-UP) (S/N: 2PZ106-UP) (S/N: 5AZ400-UP)
The rear differential fan relay is an output of the ECM. When the ECM determines that the rear differential oil temperature is too high, the ECM will energize the relay. This will cause switched + battery power to be directed to the rear differential fan motor through the relay contacts.The ECM monitors the relay circuit for abnormal conditions. When an abnormal condition is detected, a diagnostic code will be displayed. Refer to the troubleshooting section of this manual for the diagnostic codes that are associated with this relay circuit.Relay - Stop Lamp
Illustration 3 g01100463
Relay - stop lamp - (S/N: 2BW659-UP) (S/N: APX451-UP) (S/N: 2PZ106-UP) (S/N: 5AZ400-UP)
The stop lamp relay is an output of the ECM. During machine operation, the stop lamp relay is energized by the ECM when the brakes are applied by either the operator or when the ARC system is active. When the relay is energized, + battery power is directed to the stop lamps through the relay contacts.The ECM monitors the relay circuit for abnormal conditions. When an abnormal condition is detected, a diagnostic code will be displayed. Refer to the troubleshooting section of this manual for the diagnostic codes that are associated with this relay circuit.Rear Axle Lubrication Relay
Illustration 4 g01210019
Relay - rear axle lubrication - (S/N: FDB1-UP)
The rear axle lubrication relay is used to drive the rear axle supply solenoid and the rear axle diverter solenoid. These two solenoids are used to control the lubrication for the rear differential and final drives. The ECM supplies two inputs to the relay at contact 4 and contact 5. When the relay receives an input from the ECM, the relay will energize the appropriate output at contact 3 or contact 6. When a relay output is energized for a solenoid, the ECM will receive a feedback input in order to determine the status of the solenoid.Reference: For more information on the rear axle lubrication system, refer to the Systems Operation, "Additional Functions" section of this manual.