Dodge Ram Truck 1500-2500-3500. Manual — part 1473

SENSOR - OXYGEN

DESCRIPTION

The Oxygen Sensors (O2S) are attached to, and protrude into the vehicle exhaust system. Depending on the
engine or emission package, the vehicle may use a total of either 2 or 4 sensors.

Federal Emission Packages : Two sensors are used: upstream (referred to as 1/1) and downstream (referred to as
1/2). With this emission package, the upstream sensor (1/1) is located just before the main catalytic convertor. The
downstream sensor (1/2) is located just after the main catalytic convertor.

California Emission Packages: On this emissions package, 4 sensors are used: 2 upstream (referred to as 1/1
and 2/1) and 2 downstream (referred to as 1/2 and 2/2). With this emission package, the right upstream sensor (2/1)
is located in the right exhaust downpipe just before the mini-catalytic convertor. The left upstream sensor (1/1) is
located in the left exhaust downpipe just before the mini-catalytic convertor. The right downstream sensor (2/2) is
located in the right exhaust downpipe just after the mini-catalytic convertor, and before the main catalytic convertor.
The left downstream sensor (1/2) is located in the left exhaust downpipe just after the mini-catalytic convertor, and
before the main catalytic convertor.

REMOVAL

CAUTION: Never apply any type of grease to the oxygen sensor electrical connector, or attempt any sol-
dering of the sensor wiring harness.

WARNING: THE EXHAUST MANIFOLD, EXHAUST PIPES AND CATALYTIC CONVERTER BECOME VERY HOT
DURING ENGINE OPERATION. ALLOW ENGINE TO COOL BEFORE REMOVING OXYGEN SENSOR.

1. Raise and support vehicle.

2. Disconnect wire connector from O2S sensor.

CAUTION: When disconnecting sensor electrical
connector, do not pull directly on wire going into
sensor.

3. Remove O2S sensor with an oxygen sensor

removal and installation tool.

4. Clean threads in exhaust pipe using appropriate

tap.

INSTALLATION

Threads of new oxygen sensors are factory coated
with anti-seize compound to aid in removal. DO NOT
add any additional anti-seize compound to threads
of a new oxygen sensor.

1. Install O2S sensor. Tighten to 30 N·m (22 ft. lbs.)

torque.

2. Connect O2S sensor wire connector.

3. Lower vehicle.

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SWITCH - PTO

DESCRIPTION

This Powertrain Control Module (PCM) input is used only on models equipped with aftermarket Power Take Off
(PTO) units.

OPERATION

The input is used only to tell the PCM (or ECM-Diesel) that the PTO has been engaged. The PCM (or ECM) will
disable (temporarily shut down) certain OBD II diagnostic trouble codes when the PTO is engaged.

JTEC and NGC Engine Controllers: When the aftermarket PTO switch has been engaged, a 12V + signal is sent
through circuit G113 to PCM pin A13. The PCM will then sense and determine that the PTO has been activated.

CM 845 or CM 848 Diesel Engine Controllers: When the aftermarket PTO switch has been engaged, a 12V +
signal is sent through circuit G113 to ECM pin B38. The ECM will then sense and determine that the PTO has been
activated.

THROTTLE BODY

DESCRIPTION

The throttle body is located on the intake manifold. Fuel does not enter the intake manifold through the throttle body.
Fuel is sprayed into the manifold by the fuel injectors.

OPERATION

Filtered air from the air cleaner enters the intake manifold through the throttle body. The throttle body contains an air
control passage controlled by an Idle Air Control (IAC) motor. The air control passage is used to supply air for idle
conditions. A throttle valve (plate) is used to supply air for above idle conditions.

5.7L V-8 Engine:

The throttle body on the 5.7L engine is an electrically controlled unit. A mechanical cable is not used to connect the
throttle body to the accelerator pedal. The Accelerator Pedal Position Sensor (APPS) along with inputs from other
sensors sets the throttle blade to pre-determined positions.

Except 5.7L V-8 Engine:

Certain sensors are attached to the throttle body. The accelerator pedal cable, speed control cable and transmission
control cable (when equipped) are connected to the throttle body linkage arm.

A (factory adjusted) set screw is used to mechanically limit the position of the throttle body throttle plate. Never
attempt to adjust the engine idle speed using this screw. All idle speed functions are controlled by the PCM.

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REMOVAL

3.7L V-6

A (factory adjusted) set screw is used to mechanically
limit the position of the throttle body throttle plate.
Never attempt to adjust the engine idle speed
using this screw. All idle speed functions are con-
trolled by the Powertrain Control Module (PCM).

1. Remove air cleaner tube at throttle body.

2. Disconnect throttle body electrical connectors at

IAC motor and TPS.

3. Remove all control cables from throttle body (lever)

arm. Refer to the Accelerator Pedal and Throttle
Cable section for removal/installation procedures.

4. Disconnect necessary vacuum lines at throttle

body.

5. Remove 3 throttle body mounting bolts (2).

6. Remove throttle body from intake manifold.

7. Check condition of old throttle body-to-intake man-

ifold o-ring.

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4.7L V-8

1. Remove air duct and air resonator box at throttle

body.

2. Disconnect throttle body electrical connectors at

IAC motor and TPS.

3. Remove vacuum line at throttle body.

4. Remove all control cables from throttle body (lever)

arm. Refer to Accelerator Pedal and Throttle Cable.

5. Remove three throttle body mounting bolts (1).

6. Remove throttle body from intake manifold.

5.7L V-8

CAUTION: Do not use spray (carb) cleaners on any part of the throttle body. Do not apply silicone lubri-
cants to any part of the throttle body.

1. Remove air duct and air resonator box at throttle

body.

2. Disconnect electrical connector (2) at throttle body.

3. Remove 4 throttle body mounting bolts (4).

4. Remove throttle body from intake manifold.

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