User Manual
UT108/109 OPERATING MANUAL
42
J. Dwell Testing (see gure 13)
It was very important in the past to test the dwell of the cut-off switch of an ignition system.
The dwell testing means the duration when the cut-off switch remains off when the cam
is turning. Now as an automobile is ignited electronically, it is no longer necessary to
adjust the dwell. In addition, the dwell testing can also be used to test a mixed-controlled
solenoid.
(e.g. GM feedback carburetor).
1. Set the rotary switch to RPM X10 DWELL. Press RANGE button to select the number
of cylinders and press BLUE button to select DWELL measurement mode.
2. insert the red test lead into the V terminal and the black test lead into the COM terminal.
Connect the ends to be tested as illustrated.
If the cut-off switch of an ignition system is tested, connect the red test lead probe
to the primary negative end of the ignition coil. (Refer to the automotive servicing
manual for the specic position.)
If the dwell of an arbitrary ON/OFF equipment is tested, connect the red probe to the
end of the equipment, xed with an ON/OFF switch.
3. Connect the black test lead probe to the good ground terminal of the automobile.
4. Read the ignition dwell of the tested automobile directly from the display