Yamaha XT660R Service Manual page 362

Fault code No. 42
Used diagnostic code No. 07 (speed sensor) → A1 ~ A4 / No. 21 (neutral switch) → B1 ~ B4
Order Item/components
B-1 Coupler connections
Neutral switch connector
Wiring harness ECU coupler
B-2 Open or short circuit in the wire har-
ness
B-3 Faulty shift drum (neutral detection
area)
B-4 Defective neutral switch
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.
between neutral switch and relay unit
Sky blue - Sky blue
between relay unit and ECU
Blue/Yellow - Blue/Black
Replace if defective.
Refer to "TRANSMISSION" in chapter 5.
Execute the diagnostic mode. (Code No. 21)
Replace the switch if it is defective.
Refer to "CHECKING THE SWITCHES" in chap-
ter 8.
7 - 19
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).