Yamaha MBK MW125 2014, Service Manual

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FUEL INJECTION SYSTEM
8-27
EAS30505
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 en-
gine 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
number 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 while 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 appro-
priate substitute characteristic operation, and alerts the rider of the detected malfunction by illuminat-
ing the engine trouble warning light.
• After the engine stops, the engine trouble warning light will display the lowest error code (or it will be
displayed on the Yamaha diagnostic tool), which remains stored in ECU memory until deleted.
Engine trouble warning light fault code indication
Digit of 10: Cycles of 1 sec. ON and 1.5 sec. OFF.
Digit of 1: Cycles of 0.5 sec. ON and 0.5 sec. OFF.
Example: 42
Engine trouble warning light indication and fuel injection system operation
* The warning light flashes when any one of the following conditions is present and the start switch is
pushed:
1 1.5
a
b
1 1.5 1 1.5 1 1.5 3 0.5 0.5 0.5
a. Light ON
b. Light OFF
Warning light indication ECU operation Fuel injection operation Vehicle operation
Flashing*
Warning provided when
unable to start engine
Operation stopped Cannot be operated
Remains on Malfunction detected
Operated with substitute
characteristics in accor-
dance with the descrip-
tion of the malfunction
Can or cannot be operat-
ed depending on the fault
code
12: Crankshaft position sensor 39:
Injection
(open or short circuit)
19:
Blue/yellow ECU lead
(broken or disconnected)
41:
Lean angle sensor
(open or short circuit)
30:
Lean angle sensor
(latch up detected)
50:
ECU internal malfunction
(memory check error)