2001 DODGE RAM sensor

OPERATION
The heated seat module receives fused battery cur-
rent through the energized heated seat relay in the
Junction Block (JB) only when the engine is running.
The heated seat switches receive battery current
through a fused ignition switch output (run) circuit
only when the ignition switch is in the On position.
The heated seat module shares a common ground cir-
cuit with each of the heated seat elements. The
heated seat elements will only operate when the sur-
face temperature of the seat cushion cover at the
heated seat sensors is below the designed tempera-
ture set points of the system.
The heated seat module will automatically turn off
the heated seat elements if it detects a short in the
heated seat element circuit or a heated seat sensor
value that is out of range. The heated seat system
will also be turned off automatically whenever the
ignition switch is turned to any position except On or
if the engine quits running. If the ignition switch is
turned to the Off position or if the engine quits run-
ning while a heated seat is turned ON, the heated
seat will remain Off after the engine is restarted
until a heated seat switch is depressed again.
The heated seat module monitors inputs from the
heated seat sensors and the heated seat switches. In
response to these inputs the heated seat module uses
its internal programming to control outputs to the
heated seat elements in both front seats and to con-
trol the heated seat LED indicator lamps located in
both of the heated seat switches. The heated seat
module is also programmed to provide a self-diagnos-
tic capability. When the module detects certain fail-
ures within the heated seat system, it will provide a
visual indication of the failure by flashing the indica-
tor lamps in the heated seat switches.
DIAGNOSIS & TESTING - HEATED SEAT
SYSTEM
SELF-DIAGNOSIS
The heated seat system is capable of performing
some self-diagnostics. The following table depicts the
various failure modes which will be reported to the
vehicle operator or technician by flashing the individ-
ual heated seat switch Light Emitting Diode (LED)
indicator lamps. See the Heated Seat System Self-Di-
agnosis table for the diagnostic routines. The driver
side heated seat switch indicator lamps will flash if a
failure occurs in the driver side heated seat, and the
passenger side heated seat switch indicator lamps
will flash for a passenger side heated seat failure. If
a monitored heated seat system failure occurs, the
switch indicator lamps will flash at a pulse rate of
about one-half second on, followed by about one-half
second off for a duration of about one minute afterthe switch for the faulty heated seat is depressed in
either the Low or High direction. This process will
repeat every time the faulty heated seat switch is
actuated until the problem has been corrected.
Heated Seat System Self-Diagnosis
Monitored FailureSwitch High
Indicator LampSwitch Low
Indicator Lamp
Heated Seat
Element ShortedFlashing Flashing
Heated Seat
Element OpenFlashing Off
Heated Seat
Sensor Value Out
of RangeOff Flashing
TESTING
Refer toPower Seatin the index of this service
manual for the location of complete heated seat sys-
tem wiring diagrams. Before testing the individual
components in the heated seat system, perform the
following preliminary checks:
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. DISCONNECT AND ISO-
LATE THE BATTERY NEGATIVE (GROUND) CABLE,
THEN WAIT TWO MINUTES FOR THE AIRBAG SYS-
TEM CAPACITOR TO DISCHARGE BEFORE PER-
FORMING FURTHER DIAGNOSIS OR SERVICE. THIS
IS THE ONLY SURE WAY TO DISABLE THE AIRBAG
SYSTEM. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
²If the heated seat switch back lighting and the
cluster illumination lamps do not illuminate with the
headlamps or park lamps turned On, refer toInstru-
ment Clusterin the index of this service manual for
the location of the proper cluster illumination lamps
diagnosis and testing procedures. If the heated seat
switch back lighting does not illuminate, but the
cluster illumination lamps do illuminate with the
headlamps or park lamps turned On, refer to
Heated Seat Switchin this section for the location
of the proper heated seat switch diagnosis and test-
ing procedure.
²If a single indicator lamp for one heated seat
switch does not operate and the heated seat elements
do heat, refer toHeated Seat Switchin this section
for the location of the proper heated seat switch diag-
nosis and testing procedure.
8G - 6 HEATED SEAT SYSTEMBR/BE
HEATED SEAT SYSTEM (Continued)

(3) Reconnect the two instrument panel wire har-
ness connectors to the connector receptacles on the
backs of the heated seat switches.
(4) Position the heated seat switch bezel and both
switches in the instrument panel mounting hole as a
unit.
(5) Install and tighten the three screws that secure
the heated seat switch bezel to the instrument panel.
Tighten the screws to 2.2 N´m (20 in. lbs.).
(6) Install the cluster bezel onto the instrument
panel. Refer toCluster Bezelin the index of this
service manual for the location of the proper cluster
bezel installation procedures.
(7) Reconnect the battery negative cable.
HEATED SEAT ELEMENT
DESCRIPTION
Vehicles equipped with the optional heated seat
system have two sets of electrically operated heating
element grids located in each outboard seating posi-
tion of the front seat, one set for the seat cushion
and the other set for the seat back. Each of the
heated seat element grids consists of a single length
of resistor wire that is routed in a zigzag pattern and
captured between the leather trim cover and the
foam rubber backing on the underside of its respec-
tive seat cushion trim cover and seat back trim cover
assembly. Short pigtail wires with connectors (Fig. 5)
are soldered to each end of each resistor wire ele-
ment grid, which connect all of the element grids foreach seating position to each other in series with the
heated seat module through the seat wire harness.
One temperature sensor is used for each outboard
seating position of the front seat, and it is located in
the center insert area of the seat cushion cover. The
heated seat sensors and their pigtail wires are also
captured between the leather trim cover and the
foam rubber backing on the underside of their
respective seat cushion trim cover assemblies. The
heated seat sensors are Negative Thermal Coefficient
(NTC) thermistors. The sensors for both front seats
receive a voltage feed from a single output of the
heated seat module, but the module receives individ-
ual sensor inputs from the driver side and passenger
side sensors.
The heated seat elements and sensors cannot be
repaired. If damaged or faulty, the front seat cushion
trim cover or front seat back trim cover assembly
must be replaced. Refer toFront Seat Cushion
Cover - Quad CaborFront Seat Back Cover -
Quad Cabin the index of this service manual for
the location of the proper front seat trim cover
removal and installation procedures.
OPERATION
One end of the heated seat element resistor wire is
connected to a ground feed at all times through a
splice in the heated seat module ground circuit. Bat-
tery current is directed to the other end of the heated
seat element resistor wire by the energized N-chan-
nel Field Effect Transistor (N-FET) located within
the heated seat module. The heated seat module will
energize the N-FET only when the heated seat
switch is in the Low or High position and the heated
seat sensor indicates that the seat cushion surface
temperature is below the selected (Low or High) tem-
perature set point. As electrical current passes
through the heating element grid, the resistance of
the wire used in the element disperses some of that
electrical current in the form of heat. The heat pro-
duced by the heated seat element grid then radiates
through the underside of the seat cushion and seat
back trim covers, warming the seat cover and its
occupant.
The resistance of the heated seat sensor increases
and decreases as the surface temperature of the seat
cushion cover changes. The heated seat module sup-
plies each sensor with a voltage feed, then detects
the sensor resistance by monitoring the voltage of the
separate sensor return circuits. The heated seat mod-
ule compares the heated seat sensor resistance (seat
cushion surface temperature) with the heated seat
switch resistance (Low or High set point) to deter-
mine when the heated seat element grids need to be
cycled on or off in order to maintain the selected tem-
perature set point.
Fig. 5 Heated Seat Cushion Trim Cover
1 - TO SEAT BACK COVER
2 - TO SEAT WIRE HARNESS
3 - FOAM PADDING
4 - HEATED SEAT CUSHION TRIM COVER
5 - TO ELEMENT GRIDS
6 - TO ELEMENT GRIDS AND SENSOR
8G - 10 HEATED SEAT SYSTEMBR/BE
DRIVER SEAT HEATER SWITCH (Continued)

DIAGNOSIS & TESTING - HEATED SEAT
ELEMENT AND SENSOR
The heated seat module will self-diagnose shorted
or open heated seat element circuits and the sensor
circuits. Refer toHeated Seat Systemin this sec-
tion for the location of the proper heated seat system
diagnosis and testing procedures. To manually check
the heated seat element and sensor circuits, proceed
as follows. The wire harness connectors for the seat
cushion heated seat element and sensor and for the
seat back heated seat element are located under the
seat, near the rear edge of the seat cushion frame.
Refer toWiring Diagramsfor the location of com-
plete heated seat system wiring diagrams.
HEATED SEAT ELEMENT
(1) Disconnect and isolate the battery negative
cable. Disconnect the 4-way heated seat wire harness
connector. Check for continuity between the two
heated seat element circuit cavities in the seat cush-
ion trim cover half of the 4-way heated seat wire har-
ness connector. There should be continuity. If OK, go
to Step 2. If not OK, go to Step 3.
(2) Check for continuity between one of the heated
seat element circuit cavities in the seat cushion trim
cover half of the 4-way heated seat wire harness con-
nector and the seat cushion frame. There should be
no continuity. If OK, go to Step 5. If not OK, go to
Step 4.
(3) Disconnect the 2-way heated seat wire harness
connector between the seat cushion trim cover and
the seat back trim cover. Check for continuity
between the heated seat element circuit cavity and
the ground circuit cavity in the seat back trim cover
half of the 2-way heated seat wire harness connector.
There should be continuity. If OK, go to Step 5. If not
OK, replace the faulty seat back trim cover unit.
(4) Check for continuity between the heated seat
element circuit cavity in the seat back trim cover half
of the 2-way heated seat wire harness connector and
the seat back frame. There should be no continuity. If
OK, go to Step 5. If not OK, replace the faulty seat
back trim cover unit.
(5) Test the seat wire harness between the heated
seat module connector and the 4-way heated seat
wire harness connectors for shorted or open circuits.
If OK, replace the faulty seat cushion trim cover
unit. If not OK, repair the shorted or open seat wire
harness as required.
HEATED SEAT SENSOR
(1) Disconnect and isolate the battery negative
cable. Disconnect the 4-way heated seat wire harness
connector. Using an ohmmeter, check the resistance
between the heated seat sensor input circuit cavity
and the heated seat sensor feed circuit cavity in theseat cushion cover half of the 4-way heated seat wire
harness connector. The heated seat sensor resistance
should be between 1 kilohm and 200 kilohms. If OK,
go to Step 2. If not OK, replace the faulty seat cush-
ion trim cover unit.
(2) Test the seat wire harness between the heated
seat module connector and the 4-way heated seat
wire harness connector for shorted or open circuits. If
OK, refer toHeated Seat Modulein Electronic
Control Modules for the location of the proper heated
seat module diagnosis and testing procedures. Also
refer to the Body Diagnostic Manual for additional
diagnosis and testing procedures. If not OK, repair
the shorted or open heated seat wire harness as
required.
HEATED SEAT RELAY
DESCRIPTION
The heated seat relay is an electromechanical
device that switches battery current to the heated
seat module when the relay control coil is energized.
The heated seat relay is located in the Junction
Block (JB), on the left end of the instrument panel in
the passenger compartment (Fig. 6). The heated seat
relay is a International Standards Organization
(ISO) micro-relay. Relays conforming to the ISO spec-
Fig. 6 Heated Seat Relay
1 - JUNCTION BLOCK
2 - HEATED SEAT RELAY
3 - INSTRUMENT PANEL
4 - COMBINATION FLASHER
BR/BEHEATED SEAT SYSTEM 8G - 11
HEATED SEAT ELEMENT (Continued)

IGNITION CONTROL
TABLE OF CONTENTS
page page
IGNITION CONTROL
DESCRIPTION............................1
OPERATION.............................1
SPECIFICATIONS.........................2
AUTOMATIC SHUT DOWN RELAY
DESCRIPTION............................3
OPERATION.............................3
DIAGNOSIS AND TESTING..................3
ASD AND FUEL PUMP RELAYS.............3
REMOVAL...............................4
INSTALLATION............................5
CAMSHAFT POSITION SENSOR
DESCRIPTION............................5
OPERATION.............................5
REMOVAL...............................7
INSTALLATION............................8
DISTRIBUTOR
DESCRIPTION...........................10
OPERATION.............................11
REMOVAL..............................11
INSTALLATION...........................11
DISTRIBUTOR CAP
DIAGNOSIS AND TESTING.................12
DISTRIBUTOR CAP.....................12DISTRIBUTOR ROTOR
DIAGNOSIS AND TESTING.................13
DISTRIBUTOR ROTOR...................13
IGNITION COIL
DESCRIPTION...........................13
OPERATION.............................14
REMOVAL..............................14
INSTALLATION...........................15
SPARK PLUG
DESCRIPTION...........................16
OPERATION.............................16
DIAGNOSIS AND TESTING.................16
SPARK PLUG CONDITIONS...............16
REMOVAL..............................18
CLEANING..............................19
INSTALLATION...........................19
SPARK PLUG CABLE
DESCRIPTION...........................19
OPERATION.............................19
DIAGNOSIS AND TESTING.................19
SPARK PLUG CABLES...................19
REMOVAL..............................20
INSTALLATION...........................20
IGNITION CONTROL
DESCRIPTION - 8.0L V-10
The ignition system used on the 8.0L V±10 engine
does not use a conventional mechanical distributor.
The system will be referred to as a distributor-less
ignition system.
DESCRIPTION - V-6/V-8
The ignition systems used on the 3.9L V-6, the
5.2L V-8 and the 5.9L V-8 are basically identical.
OPERATION - 8.0L V-10
The ignition coils are individually fired, but each
coil is a dual output. Refer to Ignition Coil for addi-
tional information.
The ignition system is controlled by the Powertrain
Control Module (PCM) on all engines.
The ignition system consists of:
²Spark Plugs
²Ignition Coil packs containing individual coils²Secondary Ignition Cables
²Powertrain Control Module (PCM)
²Also to be considered part of the ignition system
are certain inputs from the Crankshaft Position,
Camshaft Position, Throttle Position and MAP Sen-
sors
OPERATION - V-6/V-8
The ignition system is controlled by the Powertrain
Control Module (PCM) on all engines.
The ignition system consists of:
²Spark Plugs
²Ignition Coil
²Secondary Ignition Cables
²Distributor (contains rotor and camshaft position
sensor)
²Powertrain Control Module (PCM)
²Also to be considered part of the ignition system
are certain inputs from the Crankshaft Position,
Camshaft Position, Throttle Position and MAP Sen-
sors
BR/BEIGNITION CONTROL 8I - 1

SPECIFICATIONS
SPECIFICATIONS - TORQUE - IGNITION
DESCRIPTION N´m Ft. Lbs. In. Lbs.
Camshaft Position SensorÐ8.0L Engine 6 50
Crankshaft Position SensorÐAll Engines 8 70
Distributor Hold Down Bolt 23 17
Ignition Coil MountingÐ3.9L/5.2L/5.9L
EnginesÐif tapped bolts are used550
Ignition Coil MountingÐ3.9L/5.2L/5.9L
EnginesÐif nuts/bolts are used11 100
Ignition Coil MountingÐ8.0L Engine 10 90
Spark Plugs (all engines) 41 30
SPARK PLUG CABLE ORDERÐ8.0L V-10
ENGINEENGINE FIRING ORDERÐ5.2L/5.9L V-8
ENGINES
ENGINE FIRING ORDERÐ3.9L V-6 ENGINE
Spark Plug Cable OrderÐ8.0L V-10 Engine
8I - 2 IGNITION CONTROLBR/BE
IGNITION CONTROL (Continued)

SPARK PLUG CABLE RESISTANCE
MINIMUM MAXIMUM
250 Ohms Per Inch 1000 Ohms Per Inch
3000 Ohms Per Foot 12,000 Ohms Per Foot
SPARK PLUGS
ENGINE PLUG TYPE ELECTRODE GAP
3.9L V-6 RC12LC4 1.01 mm (.040 in.)
5.2L/5.9L V-8 RC12LC4 1.01 mm (.040 in.)
8.0L V-10 QC9MC4 1.14 mm (.045 in.)
IGNITION COIL RESISTANCEÐ3.9L/5.2L/5.9L ENGINES
COIL MANUFACTURERPRIMARY RESISTANCE
21-27ÉC (70-80ÉF)SECONDARY RESISTANCE 21-27ÉC
(70-80ÉF)
Diamond 0.97 - 1.18 Ohms 11,300 - 15,300 Ohms
Toyodenso 0.95 - 1.20 Ohms 11,300 - 13,300 Ohms
IGNITION COIL RESISTANCEÐ8.0L V-10
ENGINE
Primary Resistance: 0.53-0.65 Ohms. Test across the
primary connector. Refer to text for test procedures.
Secondary Resistance: 10.9-14.7K Ohms. Test
across the individual coil towers. Refer to text for test
procedures.
IGNITION TIMING
Ignition timing is not adjustable on any engine.
AUTOMATIC SHUT DOWN
RELAY
DESCRIPTION - PCM OUTPUT
The 5±pin, 12±volt, Automatic Shutdown (ASD)
relay is located in the Power Distribution Center
(PDC). Refer to label on PDC cover for relay location.
OPERATION - PCM OUTPUT
The ASD relay supplies battery voltage (12+ volts)
to the fuel injectors and ignition coil(s). With certain
emissions packages it also supplies 12±volts to the
oxygen sensor heating elements.
The ground circuit for the coil within the ASD
relay is controlled by the Powertrain Control Module
(PCM). The PCM operates the ASD relay by switch-
ing its ground circuit on and off.The ASD relay will be shut±down, meaning the
12±volt power supply to the ASD relay will be de-ac-
tivated by the PCM if:
²the ignition key is left in the ON position. This
is if the engine has not been running for approxi-
mately 1.8 seconds.
²there is a crankshaft position sensor signal to
the PCM that is lower than pre-determined values.
OPERATION - ASD SENSE - PCM INPUT
A 12 volt signal at this input indicates to the PCM
that the ASD has been activated. The relay is used to
connect the oxygen sensor heater element, ignition
coil and fuel injectors to 12 volt + power supply.
This input is used only to sense that the ASD relay
is energized. If the Powertrain Control Module
(PCM) does not see 12 volts at this input when the
ASD should be activated, it will set a Diagnostic
Trouble Code (DTC).
DIAGNOSIS AND TESTING - ASD AND FUEL
PUMP RELAYS
The following description of operation and
tests apply only to the Automatic Shutdown
(ASD) and fuel pump relays. The terminals on the
bottom of each relay are numbered. Two different
types of relays may be used, (Fig. 1) or (Fig. 2).
²Terminal number 30 is connected to battery volt-
age. For both the ASD and fuel pump relays, termi-
nal 30 is connected to battery voltage at all times.
BR/BEIGNITION CONTROL 8I - 3
IGNITION CONTROL (Continued)

INSTALLATION
The ASD relay is located in the Power Distribution
Center (PDC) (Fig. 3). Refer to label on PDC cover
for relay location.
(1) Install relay to PDC.
(2) Install cover to PDC.
CAMSHAFT POSITION
SENSOR
DESCRIPTION - DIESEL
The three-wire Camshaft Position Sensor (CMP) is
located below the fuel injection pump (Fig. 4). It is
attached to the back of the timing gear cover hous-
ing.
DESCRIPTION - 3.9L/5.2L/5.9L
The Camshaft Position (CMP) sensor is located in
the distributor.
DESCRIPTION - 8.0L
The Camshaft Position (CMP) sensor is located on
the timing chain case/cover on the left-front side of
the engine (Fig. 5).
OPERATION - DIESEL
The Camshaft Position Sensor (CMP) performs
multiple functions. One function is to detect engine
speed (rpm). Another function is to relate crankshaft
position and Top Dead Center (TDC) of the number 1
cylinder. Because the CMP is now used to relate
crankshaft position,the Crankshaft Position Sen-
sor (CKP) is no longer used.The CMP (Fig. 6) contains a hall effect device
called a sync signal generator to generate a sync sig-
nal.
The CMP uses three wires (circuits) for operation.
One wire supplies a 5±volt signal from the Engine
Control Module (ECM). Another wire supplies a sen-
sor ground. The third wire supplies a signal back to
the ECM relating engine speed and crankshaft posi-
tion.
Fig. 3 Power Distribution Center (PDC)
1 - POWER DISTRIBUTION CENTER (PDC)
Fig. 4 Camshaft Position Sensor (CMP) Location
1 - CAMSHAFT POSITION SENSOR (CMP)
2 - BOTTOM OF FUEL INJECTION PUMP
Fig. 5 CMP Sensor LocationÐ8.0L V-10 Engine
1 - CAMSHAFT POSITION SENSOR
2 - MOUNTING BOLT
3 - TIMING CHAIN CASE/COVER
BR/BEIGNITION CONTROL 8I - 5
AUTOMATIC SHUT DOWN RELAY (Continued)

The sensor detects machined notches on the rear
face of the camshaft drive gear (Fig. 7) to sense
engine speed.The CMP also detects an area on the camshaft
drive gear that has no notch (Fig. 7). When the sen-
sor passes this area, it tells the Engine Control Mod-
ule (ECM) that Top Dead Center (TDC) of the
number 1 cylinder is occurring. The ECM will then
adjust fuel timing accordingly.
As the tip of the sensor passes the notches, the
interruption of magnetic field causes voltage changes
from 5 volts to 0 volts.
OPERATION - 3.9L/5.2L/5.9L
The sensor contains a hall effect device called a
sync signal generator to generate a fuel sync signal.
This sync signal generator detects a rotating pulse
ring (shutter) on the distributor shaft. The pulse ring
rotates 180 degrees through the sync signal genera-
tor. Its signal is used in conjunction with the Crank-
shaft Position (CKP) sensor to differentiate between
fuel injection and spark events. It is also used to syn-
chronize the fuel injectors with their respective cylin-
ders.
When the leading edge of the pulse ring (shutter)
enters the sync signal generator, the following occurs:
The interruption of magnetic field causes the voltage
to switch high resulting in a sync signal of approxi-
mately 5 volts.
When the trailing edge of the pulse ring (shutter)
leaves the sync signal generator, the following occurs:
The change of the magnetic field causes the sync sig-
nal voltage to switch low to 0 volts.
OPERATION - 8.0L
The CMP sensor is used in conjunction with the
crankshaft position sensor to differentiate between
fuel injection and spark events. It is also used to syn-
chronize the fuel injectors with their respective cylin-
ders. The sensor generates electrical pulses. These
pulses (signals) are sent to the Powertrain Control
Module (PCM). The PCM will then determine crank-
shaft position from both the camshaft position sensor
and crankshaft position sensor.
A low and high area are machined into the cam-
shaft drive gear (Fig. 8). The sensor is positioned in
the timing gear cover so that a small air gap (Fig. 8)
exists between the face of sensor and the high
machined area of cam gear.
When the cam gear is rotating, the sensor will
detect the machined low area. Input voltage from the
sensor to the PCM will then switch from a low
(approximately 0.3 volts) to a high (approximately 5
volts). When the sensor detects the high machined
area, the input voltage switches back low to approx-
imately 0.3 volts.
Fig. 6 Camshaft Position Sensor (CMP)
1 - GEAR HOUSING
2 - O-RING
3 - CMP SENSOR
4 - CMP HEX HEAD BOLT
Fig. 7 Notches at Rear Of Camshaft Drive Gear
1 - CAMSHAFT DRIVE GEAR
2 - NOTCHES
3 - CAMSHAFT POSITION SENSOR (CKP)
4 - NO NOTCH
8I - 6 IGNITION CONTROLBR/BE
CAMSHAFT POSITION SENSOR (Continued)