Dtc 122- tps1 signal voltage low, Dtc 122- tps1 signal voltage low -167 – JLG 450A_AJ Series II Service Manual User Manual
Page 217
SECTION 3 - CHASSIS & TURNTABLE
3121180
– JLG Lift –
3-167
DTC 122- TPS1 Signal Voltage Low
• 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 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
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 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 sets if TPS1 voltage is lower than the low voltage
limit as defined in the diagnostic calibration at any operat-
ing condition while the engine is cranking or running. The
limit is generally set to 4.90 VDC. In many cases, this con-
dition 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.
E
le
c
tro
n
ic
T
h
ro
ttle
A
c
tu
a
to
r w
/Se
ria
l
P
o
s
itio
n
F
e
e
db
a
c
k
2
1
6
1
3
1
2
1
5
V
_e
x
t
V
s
=
+
5
V
DC
5
V
_
rtn
T
P
S
1
T
P
S
S
ER
+
+
-M
o
to
r
D
B
W-
D
B
W+
E
C
M
H
-B
rid
g
e
1
9
T
P
S
S
ER
-
S
e
ria
l x
m
itte
r
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