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| Illustration 1 | g01014007 |
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777F series position switch location (1) Magnet assembly (2) Body up or down switch | |
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| Illustration 2 | g06073308 |
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777E series position switch location (1) Magnet assembly (2) Body up or down switch | |
The body up or down switch (2) is on a bracket on the rear frame. The magnet assembly (1) is connected to the dump body. When the dump body is raised, the body up or down switch (2) sends a signal to the Chassis Electronic Control Module (ECM). The signal indicates that the dump body is in the UP position. When the dump body is lowered, the magnet assembly (1) will pass in front of the body up or down switch (2) and a signal will be sent to the Chassis (ECM). This signal indicates that the dump body is DOWN. The adjustment of the body up or down switch (2) isvery important. Refer to the Hydraulic System Testing and Adjusting, "Electronic Control (Body Down or Up Switch) - Adjust" for the proper adjustment procedure.
The body up or down switch (2) will limit the top gear that is being used while the dump body is in the UP position. The Chassis (ECM) comes from the factory with the top gear value that is set to FIRST gear. The transmission will not shift past FIRST gear until the dump body is down. The top gear value is programmable by utilizing the Electronic Technician (ET). The top gear value can be changed to SECOND gear, THIRD gear, or FOURTH gear.
The signal from the body up or down switch (2) is also used to control the SNUB position of the hoist control valve. The Chassis (ECM) will signal the hoist proportioning solenoids to move the hoist control valve to the SNUB position when the dump body that is being lowered nears the frame. The speed in FLOAT is reduced in the SNUB position to prevent the dump body from contacting the frame too hard.
The signal from the body up or down switch (2) is used to provide warnings to the operator when the truck is moving with the dump body in the UP position.