Chrysler RG Voyager. Manual - part 494

BOOST PRESSURE SENSOR

DESCRIPTION

The boost pressure/ intake air temperature sensor

is mounted to the top of the intake manifold. The
sensor allows the ECM to monitor air pressure
within the intake manifold. This sensor is also used
to monitor the intake air temperature (Fig. 12).

OPERATION

When the intake manifold pressure is low sensor

voltage output is 0.25-1.8 volts at the ECM. When
the intake manifold pressure is high due to turbo
boost, sensor voltage output is 2.0-4.7 volts. The sen-
sor receives a 5-volts reference from the ECM. Sensor
ground is also provides by the ECM. The ECM uses
boost pressure combined with intake air temerature
to determine the volume of air entering the engine.

DIAGNOSIS AND TESTING - BOOST
PRESSURE/INTAKE AIR TEMPERATURE
SENSOR

If the boost pressure sensor fails, the ECM records

a DTC into memory and continues to operate the
engine in one of the three limp-in modes. When the
ECM is operating in this mode, a loss of power will
be present, as if the turbocharger was not operating.
The best method for diagnosing faults with the boost
pressure sensor is with the DRB III

t scan tool. Refer

to the Diesel Powertrain Diagnostic Manual for more
information.

Refer to On-Board Diagnostics in Emissions Con-

trol System for a list of Diagnostic Trouble Codes
(DTC’s) for certain fuel system components.

INTAKE AIR TEMPERATURE
SENSOR

DESCRIPTION

The boost pressure sensor/intake air temperature

sensor is located in the top of the intake manifold
(Fig. 13). The intake air temperature sensor is used
to measure the intake air temperature. The intake
air temperture sensor is a dual purpose sensor. It is
also used as a boost pressure sensor.

OPERATION

The intake air temperature sensor is a negative

temperature coefficient (NTC) thermistor (resistance
varies inversly with temperature). This means at
cold air temperature its resistance is high, so the
voltage signal will be high. As intake air temperature
increases, sensor resistance decreases and the signal
voltage will be low. This allows the sensor to provide
an analog voltage signal (0.2-4.8 volts) to the ECM.

Fig. 12 BOOST PRESSURE SENSOR / INTAKE AIR

TEMPERATURE SENSOR

Fig. 13 BOOST PRESSURE SENSOR/INTAKE AIR

TEMPERATURE SENSOR LOCATION

1 - FUEL RAIL
2 - FUEL PRESSURE SENSOR
3 - BOOST PRESSURE/INTAKE AIR TEMPERATURE SENSOR
4 - CYLINDER HEAD COVER/INTAKE MANIFOLD

14a - 24

FUEL INJECTION

REMOVAL

(1) Disconnect negative battery cable.
(2) Remove engine cover retaining bolts and cover-

(Refer to 9 - ENGINE - REMOVAL).

(3) Disconnect intake air temperature electrical

connector.

(4) Remove intake air temperature sensor retain-

ing screws and sensor (Fig. 13).

INSTALLATION

(1) Install intake air temperature sensor and

retaining bolts (Fig. 13). Torque to 5.4 N·m.

(2) Connect intake air temperature sensor.
(3) Install engine cover and retaining bolts (Refer

to 9 - ENGINE - INSTALLATION).

CRANKSHAFT POSITION
SENSOR

DESCRIPTION

The crankshaft position sensor is mounted in the

right rear of the engine block below the turbocharger
(Fig. 14). This sensor is used to detect engine speed.

OPERATION

The crankshaft position sensor is a magnetic pickup

type sensor that generates an A/C signal. The sensor
contains a permanent magnet and a coil of wire. The
sensor generates an A/C signal each time a notch in the
reluctor wheel on the crankshaft passes across the per-
manent magnet. The ECM calculates engine speed based
on the frequency of the A/C signal.

MASS AIR FLOW (MAF)
SENSOR

DESCRIPTION

The Mass Air Flow (MAF) Sensor is mounted

inline in the air intake between the air filter and the
turbocharger (Fig. 15).

OPERATION

The ECM uses the mass air flow (MAF) sensor to

measure air density. The MAF sensor contains a
ceramic element. A signal voltage is provided to the
element. As engine speed increases, airflow across
the ceramic element increases. Changes in air flow
and air density cause the temperature of the ceramic
element to fluxuate. The ceramic element changes
resistance respectively to changes in temperature.
The change in resistance varies the signal voltage
output to the ECM. The ECM/PCM relay supplies
battery power the to MAF sensor. Ground is provided
by the ECM. The MAF sensor signal is provided to
the ECM.

REMOVAL

(1) Disconnect negative battery cable.
(2) Disconnect MAF sensor electrical connector

(Fig. 16).

(3) Loosen MAF sensor retaining clamps (Fig. 16).
(4) Remove MAF sensor from airduct (Fig. 16).

Fig. 14 CRANKSHAFT POSITION SENSOR

Fig. 15 MASS AIR FLOW (MAF) SENSOR

FUEL INJECTION

14a - 25

INTAKE AIR TEMPERATURE SENSOR (Continued)