Yamaha XMAX YP125R - Service manual > Fuel injection system

Circuit diagram

2. Crankshaft position sensor

4. Backup fuse (immobilizer unit and meter assembly)

5. Main switch

6. ECU fuse

7. Radiator fan motor fuse

9. Ignition fuse

10. Headlight fuse

12.Battery

13.Main fuse

17. Frame ground

18. Sidestand switch

19. Fuel pump

25.Coolant temperature sensor

26.Throttle position sensor

27. Intake air pressure sensor

28. Intake air temperature sensor

29. Lean angle sensor

30. Speed sensor

31. ECU (engine control unit)

32. Ignition coil

33. Spark plug

34. Fuel injector

35. O2 sensor

36. ISC (idle speed control) unit

40. Headlight relay

62. Multifunction meter

67. Engine trouble warning light

73. Radiator fan motor

74. Radiator fan motor relay

75. Self-diagnosis signal coupler

A. YP250R only

Ecu self-diagnostic function

The ECU is equipped with a self-diagnostic function in order to ensure that the fuel injection system is operating normally. If this function detects a malfunction in the system, it immediately operates the engine under substitute characteristics and illuminates the engine trouble warning light to alert the rider that a malfunction has occurred in the system. Once a malfunction has been detected, a fault code is stored in the memory of the ECU.

• To inform the rider that the fuel injection system is not functioning, the engine trouble warning light flashes when the start switch is being pushed to start the engine.
• If a malfunction is detected in the system by the self-diagnostic function, the ECU provides an appropriate substitute characteristic operation, and alerts the rider of the detected malfunction by illuminating the engine trouble warning light.
• After the engine has been stopped, the lowest fault code number appears on the odometer LCD.

  Once a fault code has been displayed, it remains stored in the memory of the ECU until it is deleted.

Engine trouble warning light indication and fuel injection system operation

* The warning light flashes when any one of the conditions listed below is present and the start switch is pushed:

12: Crankshaft position sensor

13: Intake air pressure sensor (open or short circuit)

14: Intake air pressure sensor (clogged or detached hose)

15: Throttle position sensor (open or short circuit)

16: Throttle position sensor (stuck)

19: Blue/yellow ECU lead (broken or disconnected)

30: Lean angle sensor (latch up detected)

33: Faulty ignition

39: Fuel injector (open or short circuit)

41: Lean angle sensor (open or short circuit)

50: ECU internal malfunction (memory check error)

Checking for a defective engine trouble warning light

The engine trouble warning light comes on for 2.0 seconds after the main switch has been set to "ON" and when the start switch is being pushed. If the warning light does not come on under these conditions, the warning light bulb may be defective.

ECU detects an abnormal signal from a sensor

If the ECU detects an abnormal signal from a sensor while the vehicle is being driven, the ECU illuminates the engine trouble warning light and provides the engine with alternate operating instructions that are appropriate for the type of malfunction.

When an abnormal signal is received from a sensor, the ECU processes the specified values that are programmed for each sensor in order to provide the engine with alternate operating instructions that enable the engine to continue operating or stop operating, depending on the conditions.

Troubleshooting method

The engine operation is not normal and the engine trouble warning light comes on.

1. Check:

• Fault code number

a. Check the fault code number displayed on the meter.

b. Identify the faulty system with the fault code number.

c. Identify the probable cause of the malfunction.

2. Check and repair the probable cause of the malfunction.

3. Perform the reinstatement action for the fuel injection system.

4. Set the main switch to "OFF", then to "ON" again, and then check that no fault code number is displayed.

TIP

If another fault code number is displayed, repeat steps (1) to (4) until no fault code number is displayed.

5. Erase the malfunction history in the diagnostic mode.

TIP

Setting the main switch to "OFF" will not erase the malfunction history.

The engine operation is not normal, but the engine trouble warning light does not come on.

1. Check the operation of the following sensors and actuators in the Diagnostic mode.

01: Throttle position sensor (throttle angle)

30: Ignition coil

36: Fuel injector

If a malfunction is detected in the sensors or actuators, repair or replace all faulty parts.

If no malfunction is detected in the sensors and actuators, check and repair the inner parts of the engine.

Diagnostic mode

It is only possible to monitor the sensor output data or check the activation of actuators by connecting the FI diagnostic tool to the vehicle and setting the diagnostic mode.

TIP

The diagnostic mode can only be set using the FI diagnostic tool. The diagnostic mode cannot be set using the meter.

FI diagnostic tool 90890-03182

Setting the diagnostic mode

1. Set the main switch to "OFF".

2. Disconnect the self-diagnosis signal coupler, and then connect the FI diagnostic tool "1" as shown.

3. While pressing the "MODE" button, set the main switch to "ON".

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• "DIAG" appears on the LCD of the FI diagnostic tool. If "CO" appears on the LCD of the FI diagnostic tool, press the "UP" button to select "DIAG".
• The "POWER" LED (green) comes on.

4. Press the "MODE" button.

TIP

The diagnostic code number "D01" appears on the LCD of the FI diagnostic tool.

5. Select the diagnostic code number corresponding to the fault code number by pressing the "UP" and "DOWN" buttons.

TIP

• The diagnostic code number appears on the LCD (01-70).
• To decrease the selected diagnostic code number, press the "DOWN" button. Press the "DOWN" button for 1 second or longer to automatically decrease the diagnostic code numbers.
• To increase the selected diagnostic code number, press the "UP" button. Press the "UP" button for 1 second or longer to automatically increase the diagnostic code numbers.

6. Check the operation of the sensor or actuator.

• Sensor operation

The data representing the operating conditions of the sensor appear on the LCD.

• Actuator operation

Press the "MODE" button.

7. Set the main switch to "OFF" to cancel the diagnostic mode.

8. Disconnect the FI diagnostic tool and connect the self-diagnosis signal coupler.

TIP

Information about each diagnostic code number is organized in this manual as follows:

• If a diagnostic code number has a corresponding fault code number, the information is shown in "TROUBLESHOOTING DETAILS".
• If a diagnostic code number does not have a corresponding fault code number, the information is shown in "DIAGNOSTIC CODE TABLE".

Troubleshooting details

This section describes the measures per fault code number displayed on the meter. Check and service the items or components that are the probable cause of the malfunction following the order given.

After the check and service of the malfunctioning part have been completed, reset the meter display according to the reinstatement method.

Fault code No.:

Fault code number displayed on the meter when the engine failed to work normally.

Diagnostic code No.:

Diagnostic code number to be used when the diagnostic mode is operated.

Diagnostic code table

The following tables contain information about diagnostic code numbers that do not have a corresponding fault code number. (These items are not listed in "TROUBLESHOOTING DETAILS".)

Communication error with the FI diagnostic tool

See also: