Yamaha 2002 TDM900, Service Manual

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1-5
Switches
Sensors
FEATURES
GEN
INFO
ECU (Electronic Control Unit)
The main functions of the ECU are ignition control, fuel control, self-diagnosis, and load control.
S
ECU’s internal construction and functions
The main components and functions of the ECU can be broadly divided into the following four items:
A. Power supply circuit
The power supply circuit obtains power from the battery (12 V) to supply the power (5 V) that is
required for operating the ECU.
B. Input interface circuits
The input interface circuits convert the signals output by all the sensors into digital signals, which
can be processed by the CPU, and input them into the CPU.
C. CPU (Central Processing Unit)
The CPU determines the condition of the sensors in accordance with the level of the signal that is
output by the respective sensor. Then, the signals are temporarily stored on the RAM in the CPU.
Based on those stored signals and the basic processing program on the ROM, the CPU calculates
the fuel injection duration, injection timing, and ignition timing, and then sends control commands
to the respective output interface circuits.
D. Output interface circuits
The output interface circuits convert the control signals output by the CPU into actuating signals for
the respective actuators in order to actuate them. They also output commands to the relay output
circuits as needed.
E. Interface circuit for communication
Communicates with the meter.