140 KENR6933
Troubleshooting Section
i02657152
Engine Te mperature S en sor
Open o r Short Circuit - Test
System Operat
ion Description:
Use this procedure under the following
conditions:
This procedure covers open circuit diagnostic codes
and short circ
uit diagnostic codes that are associated
with the following sensors:
•
Coolant tempe
rature sensor
•
Intake manifold air temperature sensor
Use this procedure to troubleshoot the system when
one of the following diagnostic codes is an active
diagnostic c
ode or a recently logged diagnostic code
or when a diagnostic code can easily be activated.
•
0110-03 Engi
ne Coolant Temperature Sensor
voltage above normal
•
0110-04 Engi
ne Coolant Temperature Sensor
voltage below normal
•
0172-03 Int
ake Manifold Air Temperature Sensor
voltage above normal
•
0172-04 Int
ake Manifold Air Temperature Sensor
voltage below normal
The followi
ng background information is related
to this procedure:
The trouble
shooting procedures for the diagnostic
codes of each temperature sensor are identical.
The temperature sensors are sensors that have
two termin
als. P2:37 on the Electronic Control
Module (ECM) is the common connection for the
engine temperature sensors. The sensor common
connectio
n is shared between the temperature
sensors. The common line is connected to terminal 2
on each sensor connector. Terminal 1 is the sensor
output. T
he signal voltage from terminal 1 of each
sensor is supplied to the appropriate terminal at ECM
Connector P2/J2.
Pull-up Voltage
The ECM continuously outputs a pull-up voltage on
the circuit for
the sensor signal wire. The ECM uses
this pull-up voltage in order to detect an open in the
signal circuit. When the ECM detects the presence
of a voltage th
at is above a threshold on the signal
circuit, the ECM will generate an open circuit FMI
code (-03) for the sensor.
If the sensor is disconnected at the sensor connector,
the presence of pull-up voltage at the sensor
connector in
dicates that the wires from the sensor
connector to the ECM are not open or shorted to
ground. If the sensor is disconnected at the sensor
connector,
the absence of pull-up voltage at the
sensor connector indicates an open in the signal wire
or a short to ground. If the sensor is disconnected at
the sensor c
onnector and the voltage at the sensor
connector is different from pull-up voltage, the signal
wire is shorted to another wire in the harness.
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