JLG 450A_AJ Series II Service Manual - Manual (Page 262)

SECTION 3 - CHASSIS & TURNTABLE
3-212 – JLG Lift – 3121180
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 posi-
tion feedback sensors. When the fuel injection pump is
electronically controlled it can control 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 actuator.
There are two types of throttle actuators, 1) actuator with
analog position feedback and 2) actuator with digital posi-
tion feedback. The first type, with analog position feed-
back, provides an analog return signal between 0 and 5
volts that is proportional 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