JLG 450A_AJ Series II Service Manual - Manual (Page 208)

SECTION 3 - CHASSIS & TURNTABLE
3-168 – JLG Lift – 3121290
DTC 2112- Unable to Reach Higher TPS
• Throttle Position Sensor.
• Check Condition-Cranking or Running.
• Fault Condition-Throttle command is 20% more than
actual throttle position.
• MIL-On during active fault.
• Engine Shut Down.
On 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 throttle
and throttle position sensor refer to these fuel injection pump
control actuators and their position feedback sensors. When
the fuel injection pump is electronically controlled it can con-
trol 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 sen-
sor to determine throttle actuator position, and is located
within the throttle actuator.
There are two types of throttle actuators, 1) actuator with ana-
log position feedback and 2) actuator with digital position
feedback. The first type, with analog position feedback, pro-
vides an analog return signal between 0 and 5 volts that is pro-
portional 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 sets if throttle command is 20% or more than actual
throttle position. During this active fault the MIL light is on and
engine will shut down.
Electronic Throttle
Actuator w/Serial
Position Feedback
2
16
13
12
1
5V_ext
Vs=+5 VDC
5V_rtn
TPS1
TPS SER +
+
-
Motor
DBW-
DBW+
ECM
H-Bridge
19
TPS SER -
Serial
xmitter