TCM FB-8 Series, Service Manual

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2. ELECTRICAL PARTS AND PROCEDURES FOR CHECKING
2.2 PROCEDURE FOR CHECKING THE CONTROLLER ASSEMBLY
SEPARATELY
2.2.1 CONTROLLER ASSEMBLY
The controller assembly controls the drive, pump and power steering motors according to signals
from the F/R lever, accelerator pedal, load handling levers, and steering wheel.
It consist of a contactor which turns the battery power supply on and off, one EPS controller and
two inverter units. Each of the controller and converter units is connected by a CAN communications
network through which necessary information is sent and received.
The drive and pump motor inverter units each consist of a CPU printed-circuit board and a main
power circuit (FET boards and capacitor boards), which control the drive and pump motors.
The EPS (electric power steering) unit consists of a CPU printed-circuit board and main power
circuit assembly which controls the EPS motor. (excluding trucks with an Orbitrol steering system.)
The information stored in memory in the motor controller or inverter unit, including settings, can be
displayed on the LCD panel by operating the switch panel.
Checking procedure
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Loose bolts and poor connector contacts
A loose nut or bolt, which secure a controllers’ power terminals, will generate heat or cause a fire.
Thoroughly clean any loose nuts or bolts with sand paper before retightening them.
Poor connector contacts will cause a system to fail to operate normally. If any poor contacts are
found, remove all dust, dirt or corrosion from the connectors and then connect and disconnect the
connectors a few times. In addition, check the lead wires for breaks and the terminals for deformation.
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Checking the controllers on the machine
It is dangerous to work on the electric system of the truck with the key switch turned on and the
battery connectors connected. Make sure the battery connectors are disconnected and wait at least 15
minutes before touching any electrical part.
If you need to make measurements with the key switch turned on and the battery connected, lift the
drive wheel off the ground to prevent the truck from moving accidentally should the drive motor turn
suddenly.
Apply the parking brake, measure the maximum current while performing switch-back and load
handling operations.