Yamaha YZ 2023 Series, Owner'S Service Manual

Page: 306 / 378

FUEL INJECTION SYSTEM
8-19
EAM30352
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.
Engine trouble warning light indication and fuel injection system operation
* The engine trouble warning light flashes when any one of the following conditions is present and the
start switch is pushed:
Checking the engine trouble warning light
The engine trouble warning light comes on for around 2 seconds when pushing the start switch to turn
on the engine trouble warning light comes on while the start switch is being pushed.
Warning light indica-
tion
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 oper-
ated depending on the
fault code
12: Crankshaft position sensor 41:
Lean angle sensor
(open or short circuit)
30:
Lean angle sensor
(latch up detected)
50:
ECU internal malfunction
(faulty ECU memory)
33:
Ignition coil
(Malfunction detected in the primary wire of
the ignition coil)
a b
c d c
a. Start switch is not being pushed.
b. Start switch is being pushed.
c. Engine trouble warning light goes off
d. Engine trouble warning light comes on for
around 2 seconds