JLG 460SJ Service Manual - Manual (Page 212)

SECTION 3 - CHASSIS & TURNTABLE
3-160 – JLG Lift – 3120895
• Throttle Position Sensor 1
• Check Condition-Key On, Engine Off
• Fault Condition-TPS1 sensor voltage lower than the
limit defined in the diagnostic calibration
• Corrective Action(s): Sound audible warning or illumi-
nate secondary warning lamp, shutdown engine
• Non-emissions related fault
In the case of a diesel engine, an actuator controls a fuel
injection pump, directly affecting the fueling level into the
cylinders. This may be by direct manipulation of the fuel
injection pump rack or by manipulation of the mechanical
governor control level or "throttle arm." In the DGC ECM
and EDIS, references to the throttle and throttle position
sensor refer to these fuel injection pump control actuators
and their position feedback sensors. When the fuel injec-
tion pump is electronically controlled it can be used to
control the idle stability and limit engine speed based on
operating conditions.
The Throttle Position Sensor uses either;
1) a variable resistor and voltage divider circuit or
2) a non-contact hall-effect sensor to determine throttle
actuator position, and is located within the throttle actua-
tor.
There are two types of throttle actuators;
1) actuator with analog position feedback and
2) actuator with digital position feedback
The first type, with analog position feedback, provides an
analog return signal between 0 and 5 volts that is propor-
tional to the throttle actuator position. The second type,
with digital position feedback, provides a serial data signal
to the ECM with the throttle actuator position voltage level
encoded in the data stream.
This fault will set if TPS1 voltage is lower than the low volt-
age limit as defined in the diagnostic calibration at any
operating condition while the engine is cranking or run-
ning. The limit is generally set to 4.90 VDC. In many
cases, this condition is caused by the TPS sensor being
disconnected from the engine harness, an open-circuit or
short-to-ground of the TPS circuit in the wire harness, or a
failure of the sensor. This fault should be configured to
trigger an engine shutdown and the engine will not start
with this fault active.