Ecu Self-Diagnostic Function - Yamaha FZ 25 2021 Supplementary 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
gets "ON" while the main switch is turned on.
• 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
Warning light indication
Remains on
P0335: Crankshaft position sensor
Fuel injector
P0201:
(short circuit)
Checking the engine trouble warning light
The engine trouble warning light comes on for around 2 seconds after the main switch has been set to
"ON" and it comes on while the start switch is being pushed. If the warning light does not come on under
these conditions, the warning light (LED) 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 illumi-
nates 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.
FUEL INJECTION SYSTEM
ECU operation
Malfunction detected
Fuel injection operation
Operated with substitute
characteristics in accor-
dance with the descrip-
tion of the malfunction
ECU internal malfunction
P0601:
(memory check error)
6-24
ELEC
– +
Vehicle operation
Can or cannot be operat-
ed depending on the fault
code