Honda Metropolitan CHF50, Service Manual, Page: 271 / 319

IGNITION SYSTEM
16-9
Disconnect the throttle position sensor 3P connec-
tor.
Check the 3P connector for loose contact or cor-
roded terminals.
Measure the resistance between the Yellow/red and
Yellow/blue wire terminals of the sensor side con-
nector.
Measure the resistance between the Blue/green and
Yellow/blue wire terminals of the sensor side con-
nector by turning the throttle.
If the measurements are abnormal, replace the
throttle position sensor (page 16-8).
If the measurement at the ECM 26P is abnormal and
the one at the throttle position sensor 3P connector
is normal, check for an open or short circuit, or the
loose or poor connections in the wire harness.
INPUT VOLTAGE INSPECTION
Remove the luggage box (page 2-6).
Disconnect the throttle position sensor 3P connec-
tor.
Turn the ignition switch to ON and engine stop
switch to " ".
Measure the input voltage between the Yellow/red
(+) and Blue/green ( – ) wire terminals of the wire har-
ness side connector.
If the input voltage is abnormal, or if there is no
input voltage, check for an open or short circuit in
the wire harness, or loose or poor ECM connector
contact, or battery line and ignition switch circuit of
ECM (page 15-9).
If the above check is normal, replace the ECM.
REMOVAL/INSTALLATION
Remove the luggage box (page 2-6).
Disconnect the throttle position sensor 3P connec-
tor.
Remove the screw and disconnect the throttle posi-
tion sensor from the carburetor.
STANDARD: 4 – 6 k
Ω
(20
°
C/68
°
F)
Full open – Full closed position:
Resistance decrease
Full closed – Full open position:
Resistance increase
STANDARD: 4.7 – 5.3 V
YELLOW/BLUE YELLOW/RED
BLUE/GREEN
THROTTLE POSITION SENSOR
BLUE/GREEN YELLOW/RED
THROTTLE POSITION SENSOR
SCREW
CONNECTOR
THROTTLE POSITION SENSOR