Ecu Self-Diagnostic Function - Yamaha YZ 2017 Series Owner's Service Manual

ECU SELF-DIAGNOSTIC FUNCTION

EASB29B338
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
Warning light indica-
tion
Flashing*
Remains on
* The engine trouble warning light flashes when any one of the following conditions is present and
the start switch is pushed:
12: Crankshaft position sensor
30: Lean angle sensor
(latch up detected)
33: Ignition coil
(Malfunction detected in the primary wire
of the ignition coil)
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.
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
ECU operation
Warning provided
when unable to start
engine
Malfunction detected
a b
c
8-26
FUEL INJECTION SYSTEM
Fuel injection opera-
tion
Operation stopped
Operated with substi-
tute characteristics in
accordance with the
description of the mal-
function
41: Lean angle sensor
(open or short circuit)
50: ECU internal malfunction
(faulty ECU memory)
c
d
Vehicle operation
Cannot be operated
Can or cannot be oper-
ated depending on the
fault code