Suzuki Boulevard M50, Service Manual

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5-20 FI SYSTEM
FAIL-SAFE FUNCTION
FI system is provided with fail-safe function to allow the engine to start and the motorcycle to run in a mini-
mum performance necessary even under malfunction condition.
The engine can start and can run even if the above signal is not received from each sensor. But, the engine
running condition is not complete, providing only emergency help (by fail-safe circuit). In this case, it is nec-
essary to bring the motorcycle to the workshop for complete repair.
When two ignition signals or two injector signals are not received by ECM, the fail-safe circuit can not work
and ignition or injection is stopped.
ITEM FAIL-SAFE MODE
STARTING
ABILITY
RUNNING
ABILITY
IAP sensor Intake air pressure is fixed to 760
mmHg.
“YES” “YES”
TP sensor The throttle opening is fixed to full
open position.
Ignition timing is also fixed.
“YES” “YES”
ECT sensor Engine coolant temperature value is
fixed to 80 °C (176 °F).
“YES” “YES”
IAT sensor Intake air temperature value is fixed
to 40 °C (104 °F).
“YES” “YES”
Ignition signal #1 Ignition-off and #1 Fuel-cut “YES” “YES”
#2 cylinder can run.
#2 Ignition-off and #2 Fuel-cut “YES” “YES”
#1 cylinder can run.
Injection signal #1 Fuel-cut “YES” “YES”
#2 cylinder can run.
#2 Fuel-cut “YES” “YES”
#1 cylinder can run.
Secondary throttle valve
actuator Secondary throttle valve is fixed to
full close position. When motor dis-
connection or lock occurs, power
from ECM is shut off.
“YES” “YES”
STP sensor Secondary throttle valve is fixed to
full close position.
“YES” “YES”
Gear position signal Gear position signal is fixed to 5th
gear.
“YES” “YES”
Heated oxygen sensor
(E-02, 19, 24) Fuel-air compensation ratio is fixed
to normal condition.
“YES” “YES”
PAIR control solenoid valve ECM stops controlling PAIR control
solenoid valve.
“YES” “YES”
SA
MP
LE