Yamaha 2004 Rhino 660 YXR660FAS Service Manual page 392

5. If the coolant temperature warning light does not come on when the main switch to "ON", or if the
coolant temperature warning light does not come on when the temperature is high (more than
117 ~ 123 °C (242.6 ~ 253.4 °F)):
1. Bulb and bulb socket
• Check the bulb and bulb socket for conti-
nuity.
2. Thermo switch 1
• Remove the thermo switch 1 from the cyl-
inder head.
• Connect the pocket tester (Ω × 1) to the
thermo switch 1 1.
• Immerse the thermo switch 1 in coolant 2.
• Check the thermo switch 1 for continuity.
While heating the coolant use a thermom-
eter 3 to record the temperatures.
È The thermo switch 1 circuit is open and the
coolant temperature warning light is off.
É The thermo switch 1 circuit is closed and the
coolant temperature warning light is on.
Test step Coolant temperature Continuity
Less than 120 ± 3 °C
1
(248 ± 5.4 °F)
More than 120 ± 3 °C
2
(248 ± 5.4 °F)
More than 113 °C
3
(235.4 °F)
Less than 113 °C
4
(235.4 °F)
Test steps 1 & 2: Heating phase
Test steps 3 & 4: Cooling phase
WARNING
Handle the thermo switch 1 with special
care.
Never subject it to a strong shock or allow
it to be dropped. Should it be dropped, it
must be replaced.
Thermo switch 1
8 Nm (0.8 m · kg, 5.8 ft · lb)
Three bond sealock
*
SIGNALING SYSTEM
CONTINUITY
No
Yes
Yes
No
®
#10
GOOD
CONDITION
9 - 40
NO CONTINUITY
Replace the bulb and /or bulb socket.
BAD CONDITION
Replace the thermo switch 1.
– +
ELEC