December 2023 Service and Repair ManualGround ControlsPart No. 1325652GT GS™-3390 • GS™-4390 • GS™-5390 75Confirm the side-to-side level sensor setting:26 Center a lifting jack under the drive chassis atthe ground control side of the machine.27 Raise the machine approximately 6 inches /15 cm.28 Models with RT tires: Place a 3 x 10 x10 inch / 7.62 x 25 x 25 cm thick steel blockunder both wheels at the ground controls sideof the machine.Models with flotation tires: Place a 3.15 x10 x 10 inch / 8 x 25 x 25 cm thick steel blockunder both wheels at the ground controls sideof the machine.29 Lower the machine onto the blocks.30 Pull out the red Emergency stop button to theon position at the platform controls. Start theengine.31 Raise the platform approximately 16 feet /5 m.Result: The platform stops raising and the tiltalarm will sound at 180 beeps per minute.Result: The platform does not stop raising andthe tilt alarm does not sound. The level sensormust be replaced. Repeat this procedurebeginning with step 9.Note: For reference only, the output of the levelsensor should be approximately 1.7V DC. Toconfirm, connect the positive lead of a multimeterto the yellow wire at the level sensor, and thenegative lead to the black wire.32 Raise the machine slightly.33 Remove the blocks from under both wheels.34 Lower the machine and remove the jack.35 Center a lifting jack under the drive chassis atthe tank side of the machine.36 Raise the machine approximately 6 inches /15 cm.37 Models with RT tires: Place a 3 x 10 x10 inch / 7.62 x 25 x 25 cm thick steel blockunder both wheels at the ground controls sideof the machineModels with flotation tires: Place a 3.15 x10 x 10 inch / 8 x 25 x 25 cm thick steel blockunder both wheels at the ground controls sideof the machine.38 Lower the machine onto the blocks.39 Raise the platform approximately 16 feet /5 m.Result: The platform stops raising and the tiltalarm will sound at 180 beeps per minute.Result: The platform does not stop raising andthe tilt alarm does not sound. The level sensormust be replaced. Repeat this procedurebeginning with step 9.Note: For reference only, the output of the levelsensor should be approximately 3.3V DC. Toconfirm, connect the positive lead of a multimeterto the yellow wire at the level sensor, and thenegative lead to the black wire.40 Lower the platform to the stowed position.41 Raise the machine slightly.42 Remove the blocks from under both wheels.43 Lower the machine and remove the jack.Confirm the front-to-back level sensor setting:44 Center a lifting jack under the drive chassis atthe steer end of the machine.45 Raise the machine approximately 6 inches /15 cm.46 Models with RT tires: Place a 4.36 x 10 x10 inch / 11.07 x 25 x 25 cm thick steel blockunder both wheels at the steer end of themachineModels with flotation tires: Place a 4.58 x10 x 10 inch / 11.63 x 25 x 25 cm thick steelblock under both wheels at the steer end ofthe machine.