User Manual

49
UT108/109 OPERATING MANUAL
B. Switch Testing: Check the switch to see if it can work correctly.
1. The same as in Items 1 to 3 (Fuse Testing).
2. Connect the black test lead probe to one end of the switch and the red one to another
end. When the switch is connected, the reading of the meter should be displayed less
than 10 Ω. When the switch is cut off, overload “OL” should be displayed as the
reading of the meter.
C.Solenoid or Relay Testing
1. The same as in Items 1 to 3 (Fuse Testing).
2. Connect the red and black test lead probes in parallel to the two end of a solenoid or
relay. The impedance of most of solenoids or relay coils is less than 200 Ω. (See the
details in the automotive manual.)
Warning:
Both ends of a general solenoid or relay are connected with diodes.
Check to see if there is any damaged coil. Even if the coil is found satisfactory, the
solenoid or relay may still be damaged. The relay may be welded or worn due to
the frequent sparking of the contacts. The solenoid may be stuck when the coil is in
an on-position. Therefore some potential problems cannot be found in testing.