Ecu Self-Diagnostic Function - Yamaha WR250R Service Manual

EAS27350

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 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
G
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 appro-
G
priate substitute characteristic operation, and alerts the rider of the detected malfunction by illuminat-
ing the engine trouble warning light.
After the engine has been stopped, the lowest fault code number appears on the clock LCD. Once a
G
fault code has been displayed, it remains stored in the memory of the ECU until it is deleted.
Engine trouble warning light indication and FI system operation
Warning light
indication
Flashing*
Remains on
* The warning light flashes when any one of the conditions listed below is present and the start switch is pushed:
12: Crankshaft position sensor
Sidestand switch
19:
(open circuit in the wire to the ECU)
Lean angle sensor
30:
(Latch up detected)
Ignition coil
33: (Malfunction detected in the primary wire of
the ignition coil)
Checking for a defective engine trouble warning light bulb
The engine trouble warning light comes on for 1.4 seconds after the main switch has been turned to
"ON" and when the start switch is being pushed. If the warning light does not come on under these con-
ditions, the warning light bulb may be defective.
a. Main switch OFF
b. Main switch ON
c. Light OFF
d. Light ON for 1.4 seconds
ECU operation
Warning provided when
unable to start engine
Malfunction detected
a b
c
8-31
FUEL INJECTION SYSTEM
FI operation
Operation stopped
Operated with substitute
characteristics in accor-
dance with the descrip-
tion of the malfunction
Lean angle sensor
41:
(open or short-circuit)
ECU internal malfunction
50:
(faulty ECU memory)
d c
Vehicle operation
Cannot be operated
Can or cannot be oper-
ated depending on the
fault code