(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 28 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