Oshkosh JLG 1500SJ, Service And Maintenance Manual

Page: 205 / 706

SECTION 3 - CHASSIS & TURNTABLE
3121262 – JLG Lift – 3-155
DTC 123- TPS1 Signal Voltage High
• Throttle Position Sensor 1
• Check Condition-Key On, Engine Off
• Fault Condition-TPS1 sensor voltage higher than the limit
defined in the diagnostic calibration
• Corrective Action(s): Sound audible warning or illuminate
secondary warning lamp, shutdown engine
• Non-emissions related fault
In the case of a diesel engine, an actuator controls a fuel injec-
tion pump, directly affecting the fueling level into the cylin-
ders. 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, refer-
ences to the throttle and throttle position sensor refer to these
fuel injection pump control actuators and their position feed-
back sensors. When the fuel injection 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 actu-
ator 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 will set if TPS1 voltage is higher than the limit set in
the diagnostic calibration at any operating condition while the
engine is cranking or running. The limit is generally set to 4.90
VDC. In many cases, this condition is caused by a short-to-
power 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.
PINK/WHITE
4
3
5
1
2
TAN/ORANGE
GREEN/RED
PURPLE/BLUE
BLACK/GREEN