Yamaha YZ 2017 Series, Owner'S Service Manual

Page: 330 / 410

FUEL INJECTION SYSTEM
8-26
EASB29B338
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
engine 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 ap-
propriate substitute characteristic operation, and alerts the rider of the detected malfunction by illu-
minating 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 opera-
tion
Vehicle operation
Flashing* Warning provided
when unable to start
engine
Operation stopped Cannot be operated
Remains on Malfunction detected Operated with substi-
tute characteristics in
accordance with the
description of the mal-
function
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. Start switch is not being pushed.
b. Start swich is being pushed.
c. Engine trouble warning light goes off
d. Engine trouble warning light comes on for
around 2 seconds
a b
c d
c