Sym RS-50 Service Manual page 150

CARB. THERMO SWITCH
Inspection
Disconnect the thermo switch unit coupler
Remove the thermo switch unit
Disconnect the power filter unit ass'y coupler
Remove the power filter unit ass'y.
Disconnect the heater coupler
Remove the heater.
Measure the heater resistance
Resistance : 7Ω±30% (A)→ (B)
Loop the yellow and black wires and measure the
voltage of thermo switch.
1. Put the t
hermo switch unit into cold water
(below 10 degrees), see if the heater is warm.
Voltage：12V
2. Put the t
hermo switch unit into warm water
(above 20 degrees), see if the heater
temperature does not raise.
Voltage：0V
15. ELECTRICAL EQUIPMENT
Power filter unit Ass'y
Heater
7Ω±30%
B
Heater
Thermo switch unit
Earth
A
Loop the two wires
V
measure the voltage
15-17