Stop Switch - MTD 478 Series Professional Shop Manual

IGNITION SYSTEM

Stop switch

All MTD horizontal engines that are in use in North
America have a stop switch built into the throttle lever
assembly. MTD engines used on snow blowers have
an additional stop (ignition) switch in the engine
shroud.
To test the stop switch (throttle):
1. Remove the engine shroud by following the
steps described in Chapter 3: Air Intake Sys-
tems.
2. Test the remote (ignition) stop switch first by fol-
lowing the procedures described in the next sec-
tion of this chapter.
3. Disconnect the lead that runs from the module to
the stop switch. See Figure 7.2.
Disconnect switch
Figure 7.2
NOTE: The blower housing was removed for
picture clarity.
4. Connect one lead of a digital multimeter to the
lead going to the stop switch. Connect the other
lead of the digital multimeter to a good ground.
5. Set the multimeter to the ohms (Ω) scale.
6. Operate the throttle lever while watching the
multimeter.
• When the throttle is all the way to the right
(stop), the multimeter should read at or near
0.0Ω, indicating continuity. See Figure 7.3.
continuity
• When the throttle is all the way to the left (full
throttle), the multimeter should not show conti-
nuity. See Figure 7.4.
no continuity
50
Throttle lever
Switch lead
Figure 7.3
Figure 7.4