Ecu Self-Diagnostic Function - Yamaha Star XVS950A 2009 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
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 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 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
appropriate substitute characteristic operation, and alerts the rider of the detected malfunction by
illuminating the engine trouble warning light.
• After the engine has been stopped, the lowest fault code number appears on the odometer/tripme-
ter/fuel reserve tripmeter/clock LCD. Once a fault code has been displayed, it remains stored in
the memory of the ECU until it is deleted.
Engine trouble warning light indication and fuel injection system operation
Warning light indica-
tion
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
Blue/yellow ECU lead
19:
(broken or disconnected)
Lean angle sensor
30:
(latch up detected)
Checking the engine trouble warning light
The engine trouble warning light comes on for 1.4 seconds after the main switch has been turned 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.
a. Main switch "OFF"
b. Main switch "ON"
ECU operation
Warning provided
when unable to start
engine
Malfunction detected
a
b
c
FUEL INJECTION SYSTEM
Fuel injection opera-
tion
Operation stopped
Operated with substi-
tute characteristics in
accordance with the
description of the mal-
function
Lean angle sensor
41:
(open or short-circuit)
ECU internal malfunction
50:
(memory check error)
c
d
c. Engine trouble warning light off
d. Engine trouble warning light on for 1.4 sec-
onds
7-29
Vehicle operation
Cannot be operated
Can or cannot be oper-
ated depending on the
fault code