Repair manual

Engine Troubleshooting and Replacement CRT Repair
wc_tx000585gb.fm 138
8.9 Checking Wiring to and Function of Throttle Switch
See Graphic: wc_gr003438
In order for the operator presence relay to energize, the circuit through
the coil side of the relay (terminals 85 and 86) must be completed. This
is done through the throttle switch. The L/Br wire runs from terminal 86
of the operator presence relay to the throttle switch (and to the
operator presence switch). The throttle switch is a normally closed
switch and thus the circuit is completed when the throttle pedal is in the
idle position. As soon as the throttle pedal is pressed, the circuit is
broken and the operator presence relay will de-energize. However, if
the operator is in the seated position, the operator presence switch,
which is normally open, will close. The circuit for the operator presence
relay is now completed by the operator presence switch, which keeps
the operator presence relay energized, and allows the machine to
function. To check the function of the throttle switch, carry out the
following procedure:
8.9.1 Disconnect the wiring to the throttle switch (a).
8.9.2 Insert the leads of a multimeter into the wires coming from the throttle
switch.
8.9.3 Test the throttle switch for continuity when the throttle pedal is pressed
and when in the idle position (not pressed). There should be continuity
across the throttle switch when the throttle pedal is in the idle position
and no continuity when the throttle pedal is pressed.
• If the throttle switch functions accordingly, it is OK.
• If the throttle switch does not function accordingly, it has failed;
replace it.
8.9.4 Test the operator presence switch (b) in the same manner. It is a
normally open switch and thus should only have continuity when the
operator is in the seated position.
• If the operator presence switch functions accordingly, it is OK.
• If the operator presence switch does not function accordingly, it
has failed; replace it.
8.9.5 If the throttle switch is OK, check the continuity of the wiring between
the throttle switch and the operator presence relay.