Yamaha XT660R Service Manual page 361

Fault code No. 42
Used diagnostic code No. 07 (speed sensor) → A1 ~ A4 / No. 21 (neutral switch) → B1 ~ B4
Order Item/components
A-1 Coupler connections
Speed sensor coupler
ECU coupler
A-2 Open or short circuit in the wire har-
ness
A-3 Gear for detecting vehicle speed
has broken.
A-4 Defective speed sensor
FUEL INJECTION SYSTEM
Symptom A. No normal signals are received from the speed sensor.
B. Open or short circuit is detected in the neutral switch.
Check or maintenance job
Check the couplers for any pins that may have
pulled out.
Check that the couplers are securely locked.
If necessary, repair the coupler or securely con-
nect it.
Repair or replace if there is an open or short cir-
cuit between the wire harnesses.
Blue - Blue
White - White
Black/Blue - Black/Blue
Replace the gear if it is defective.
Refer to "TRANSMISSION" in chapter 5.
Execute the diagnostic mode. (Code No. 07)
Replace the sensor if it is defective.
1. Measure the speed sensor output voltage.
2. Connect the pocket tester (DC 20 V) to the
speed sensor coupler as shown.
Positive tester probe → pink 1
Negative tester probe → black/white 2
3. Set the main switch to "ON".
4. Elevate the rear wheel and slowly rotate it.
5. Measure the speed sensor output voltage.
6. Is the speed sensor OK?
1
P O/R
B/W
2
Speed sensor output voltage
When sensor is on
DC 4.8 V or more
When sensor is off
DC 0.6 V or less
7 - 18
FI
Restore method
Reinstated by starting
the engine, and input-
ting the vehicle speed
signals by operating
the motorcycle at 20
to 30 km/h (12.4 to
18.6 mi/h).
L W
B/L