Checking For A Defective Engine Trouble Warning Light Bulb; Self-Diagnostic Fanction Table - Yamaha XF50W Service Manual

EAS00901

CHECKING FOR A DEFECTIVE ENGINE TROUBLE WARNING LIGHT BULB

The engine trouble warning light comes on for 2 seconds after the main switch has been turned "ON"
and when the start switch is being pushed. If the warning light does not come on under these condi-
tions, the warning light bulb may be defective.
Main switch
OFF
Engine trouble Light
warning light OFF
EAS00902

SELF-DIAGNOSTIC FANCTION TABLE

If the ECU detects an abnormal signal from a sensorwhile the vehicle is being driven, the ECU
illuminates the engine trouble warning light and provides the engine with alternate operating instruc-
tions that are appropriate for the type of malfunction.
When an abnormal signal is received from a sensor, the ECU processes the specified values that
are programmed for each sensor in order to provide the engine with alternate operating instructions
that enable the engine to continue to operate or stop operating, depending on the conditions.
Self-diagnostic fanction table
Fault
Item
code No.
12 Crankshaft position sensor
Intake air pressure sensor
13 (open or short circuit) (pipe
14 system)
Throttle position sensor
15 (open or short circuit)(stuck)
16
19 Broken or disconnected blue/
yellow lead of the ECU
21 Coolant temperature sensor
22 Intake temperature sensor
33 Faulty ignition
37 ISC (idle speed control) valve
(stuck fully open)
FUEL INJECTION SYSTEM
Main switch
ON
Light ON for Light
OFF
2 seconds
Intialize
No normal signals are received from the
crankshaft position sensor.
Intake air pressure sensor-open or short
circuit detected.
Faulty intake air pressure sensor pipe sys-
tem.
Throttle position sensor-open or short cir-
cuit detected.
A stuck throttle position sensor is de-
tected.
Open circuit in the input line (blue/yellow
lead) of the ECU is detected.
Coolant temperature sensor-open or short
circuit is detected.
Intake temperature sensor-open or short
circuit is detected.
Open circuit detected in the primary lead
of the ignition coil.
Engine speed is high when the engine is
idling.
Symptom
7-5
FI ifl
Engine Vehicle
startability driveability
Unable Unable
Able Able
Able Able
Unable Unable
Able Able
Able Able
Unable Unable
Able Able