(4) Trouble diagnosis: The ECU will monitor the sensors, actuators, power amplifying circuit and
detecting circuit. In case of any of the following situations, like unreliable battery voltage,
unreliable air intake manifold absolute pressure singal, unreliable engine coolant temperature
signal, fuel injector driving stage trouble, incorrect oxygen sensor trouble mark level, and fuel
ration closed loop control closed, the fuel ration will be confirmed according to the basic fuel
injection time stored in the ECU.
(5) Installation notes: The tightening torque of the oxygen sensor is 50～60N·m. Apply anti-rust
oil to the renewed oxygen sensor to prevent difficult removal due to rust.
6. Electronic control unit (Fig. 1-6)
(1) Function: The ECU is the key part of the electronic control system of the engine. The sensors
provide various signals to the ECU, and the ECU calculates the signals and sends orders to the
actuators like fuel injector, ignition coil etc to control the engine.
(2) Structure: Made by a shielded housing and printed circuit board, many electronic control units
integrated on the board to control the electronic injection system.
(3) Installation: Fixed under the instrument panel sundries box with bolt, the double interfaces
ECU is adopted.
(4) LF481Q3 engine controller pin (see Table 1-1, Fig. 1-10)
Table 1-1
Pin
Number
Definition
Pin
Number
Definition
Pin
Number
Definition
J1-01 Ignition switch J1-02 Main relay rear power supply J1-03 Vehicle speed
J1-04 Pin 2, 5V power supply+ J1-05 Pin 1, 5V power supply- J1-06
Oxygen sensor signal
low
J1-07 Not used J1-08 Not used J1-09
Medium-voltage
switch
J1-10 Not used J1-11 Serial data J1-12
Crankshaft 58 teeth
signal high
J1-13 Not used J1-14 CAN line negative J1-15 CAN line positive
J1-16 Not used J1-17 Power supply 1 J1-18 Power supply 2
J1-19 Not used J1-20 Pin 1, 5V power supply+ J1-21
Pin 2, 5V power
supply-
J1-22 Trouble indicator J1-23 Not used J1-24 Throttle position
J1-25 Not used J1-26 Not used J1-27 Intake air temperature
J1-28
Crankshaft 58 teeth signal
low
J1-29 Not used J1-30 Not used
J1-31 Engine trouble indicator J1-32 Ignition switch A J1-33
Idle speed phase B
output positive
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