Ecu's Self-Diagnostic Function - Yamaha YP400T Service Manual

ECU'S SELF-DIAGNOSTIC FUNCTION

The ECU is equipped with a self-diagnostic function in order to ensure that the engine control sys-
tem is operating normally. If this function detects a malfunction in the system, it immediately oper-
ates 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 correctly, 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, this mode 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 LCD meter.
Once a fault code has been displayed, it remains stored in the memory of the ECU until it is
deleted.
EAS00900
Engine trouble warning light indication and FI system operating condition
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
19: Broken or disconnected blue/yellow lead of
the ECU
30: Lean angle cut-off switch
(latch up detected)
33: Faulty ignition
FUEL INJECTION SYSTEM
ECU's operation
Warning provided
when unable to start
engine
Malfunction detected
7 - 3
FI operation
Operation stopped
Operated with substi-
tute characteristics in
accordance with the
description of the mal-
function
39: Fuel injector
(open or short circuit)
41: Lean angle cut-off switch
(open or short circuit)
50: ECU internal malfunction
(memory check error)
FI
Vehicle operation
Unable
Able/Unable depend-
ing on the self-diag-
nostic fault code