Ecu Self-Diagnostic Function - Yamaha MBK MW125 2014 Service Manual

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
a
b
a. Light ON
b. Light OFF
Engine trouble warning light indication and fuel injection system operation
Warning light indication
Flashing*
Remains on
* The warning light flashes when any one of the following conditions is present and the start switch is
pushed:
12: Crankshaft position sensor
Blue/yellow ECU lead
19:
(broken or disconnected)
Lean angle sensor
30:
(latch up detected)
1 1.5 1 1.5
ECU operation
Warning provided when
unable to start engine
Malfunction detected
FUEL INJECTION SYSTEM
1 1.5 1 1.5 0.5 0.5 0.5
Fuel injection operation
Operation stopped
Operated with substitute
characteristics in accor-
dance with the descrip-
tion of the malfunction
Injection
39:
(open or short circuit)
Lean angle sensor
41:
(open or short circuit)
ECU internal malfunction
50:
(memory check error)
8-27
3
Vehicle operation
Cannot be operated
Can or cannot be operat-
ed depending on the fault
code