SEALED UNIT 3Y7707 - Caterpillar

Illustration 1 g03667506Open the rear access door on the right side of the machine.
Illustration 2 g03667518
Disconnect Switch ON - To activate the electrical system, insert the key for battery disconnect switch (2) and turn the key clockwise. The battery disconnect switch must be turned to the ON position before you start the engine.Wait to Disconnect Lamp (1) - This lamp is illuminated anytime that the engine start switch is in the ON position. This lamp is also illuminated when the DEF system is performing the proper shutdown procedure during a cooldown or a purge when the pump is purging fluid from the system.
Do not turn off the battery disconnect switch until the indicator lamp has turned off. If the switch is turned off when the indicator lamp is illuminated the Diesel Exhaust Fluid (DEF) system may not shutdown properly. If the DEF system does not shutdown properly, DEF could freeze and damage the pump and lines.
Illustration 3 g03793002Observe condition of Wait to Disconnect lamp (1) that is located next to the battery disconnect switch. Turn off battery disconnect switch (2) to the OFF position only after the Wait to Disconnect lamp is no longer illuminated.
Disconnect Switch OFF - To deactivate the electrical system, turn the key for battery disconnect switch (2) counterclockwise to the OFF position.The battery disconnect switch and the engine start switch perform different functions. To disable the entire electrical system, turn off the battery disconnect switch. When you only turn off the engine start switch, the battery remains connected to the electrical system.Turn the battery disconnect switch to the OFF position and remove the key when you service the electrical system or any other machine components.Note: Do not conduct any service procedures on the DEF system until the lamp is off. The indicator lamp may remain illuminated for up to 5 minutes even though the key-switch is off and the battery switch is off. When the lamp is on, the DEF system is still powered.
Never move the battery disconnect switch to the OFF position while the engine is operating. Serious damage to the electrical system could result.
Checking the Battery Disconnect System
To ensure no damage to the engine occurs, verify that the engine is fully operational before cranking the engine. Do not crank an engine that is not fully operational.
Perform the following procedure to check the battery disconnect system.
With the battery disconnect switch in the ON position, verify that electrical components in the operator compartment are functioning. Verify that the hour meter is displaying information. Verify that the engine will crank.
Turn the battery disconnect switch to the OFF position.
Verify that the following items are not functioning: electrical components in the operator compartment, hour meter, and engine cranking. If any of the items continue to function with the battery disconnect switch in the OFF position, contact your Cat dealer.