1998 DODGE RAM 1500 Ignition coil

(2) Apply a small amount of engine oil to sensor
o-ring.
(3) Install sensor into cylinder head with a slight
rocking action. Do not twist sensor into position as
damage to o-ring may result.
CAUTION: Before tightening sensor mounting bolt,
be sure sensor is completely flush to timing chain
cover. If sensor is not flush, damage to sensor
mounting tang may result.
(4) Install mounting bolt and tighten. Refer to
Torque Specifications.
(5) Connect electrical connector to sensor.
5.9L Diesel
The CMP is located on the back of the timing gear
cover (Fig. 14).
(1) Clean out machined hole in back of timing gear
cover.
(2) Apply a small amount of engine oil to sensor
o-ring.
(3) Install sensor into timing gear cover with a
slight rocking action. Do not twist sensor into posi-
tion as damage to o-ring may result.
CAUTION: Before tightening sensor mounting bolt,
be sure sensor is completely flush to back of timing
chain cover. If sensor is not flush, damage to sen-
sor mounting tang may result.
(4) Install mounting bolt and tighten. Refer to
Torque Specifications.
(5) Connect electrical connector to sensor.
IGNITION COIL
DESCRIPTION
3.7L V-6
The 3.7L V-6 engine uses 6 dedicated, and individ-
ually fired coil for each spark plug (Fig. 15). Each
coil is mounted directly into the cylinder head and
onto the top of each spark plug (Fig. 16).
4.7L V-8
The 4.7L V±8 engine uses 8 dedicated, and individ-
ually fired coil (Fig. 15) for each spark plug. Each
coil is mounted directly to the top of each spark plug
(Fig. 17).
5.7L V-8
The 5.7L V±8 engine uses 8 dedicated, and individ-
ually fired coil (Fig. 18) for each pair of spark plugs.
Each coil is mounted directly to the top of each spark
plug (Fig. 19). Each coil is bolted to the valve cover.
Fig. 15 IGNITION COIL - 3.7L V-6/ 4.7L V-8
1 - O-RING
2 - IGNITION COIL
3 - ELECTRICAL CONNECTOR
Fig. 16 IGNITION COIL LOCATION - 3.7L V-6
1 - IGNITION COIL
2 - COIL MOUNTING NUT
DRIGNITION CONTROL 8I - 11
CAMSHAFT POSITION SENSOR (Continued)

OPERATION
3.7L V-6
Battery voltage is supplied to the 6 individual igni-
tion coils from the ASD relay. The Powertrain Con-
trol Module (PCM) opens and closes each ignition coil
ground circuit at a determined time for ignition coil
operation.
Base ignition timing is not adjustable.By con-
trolling the coil ground circuit, the PCM is able to set
the base timing and adjust the ignition timing
advance. This is done to meet changing engine oper-
ating conditions.
The ignition coil is not oil filled. The windings are
embedded in an epoxy compound. This provides heat
and vibration resistance that allows the ignition coil
to be mounted on the engine.
Because of coil design, spark plug cables (second-
ary cables) are not used with the 3.7L V-6 engine.
4.7L V-8
Battery voltage is supplied to the 8 individual igni-
tion coils from the ASD relay. The Powertrain Con-
trol Module (PCM) opens and closes each ignition coil
ground circuit at a determined time for ignition coil
operation.
Fig. 17 IGNITION COIL LOCATION - 4.7L V-8
1 - IGNITION COIL
2 - COIL ELECTRICAL CONNECTOR
3 - COIL MOUNTING STUD/NUT
Fig. 18 IGNITION COIL - 5.7L V-8
1 - IGNITION COIL
2 - MOUNTING BOLTS (2)
3 - BOOT TO SPARK PLUG
Fig. 19 IGNITION COIL R/I Ð 5.7L V-8
1 - SLIDE LOCK (SLIDE OUTWARD TO UNLOCK)
2 - SPARK PLUG CABLE (TO OPPOSITE CYLINDER BANK
SPARK PLUG)
3 - RELEASE LOCK / TAB (PUSH HERE)
4 - ELEC. CONNECTOR
5 - IGNITION COIL
6 - COIL MOUNTING BOLTS (2)
7 - SPARK PLUG CABLE (TO OPPOSITE CYLINDER BANK
IGNITION COIL)
8I - 12 IGNITION CONTROLDR
IGNITION COIL (Continued)

Base ignition timing is not adjustable.By con-
trolling the coil ground circuit, the PCM is able to set
the base timing and adjust the ignition timing
advance. This is done to meet changing engine oper-
ating conditions.
The ignition coil is not oil filled. The windings are
embedded in an epoxy compound. This provides heat
and vibration resistance that allows the ignition coil
to be mounted on the engine.
Because of coil design, spark plug cables (second-
ary cables) are not used with the 4.7L V-8 engine.
5.7L V-8
The ignition system is controlled by the Powertrain
Control Module (PCM) on all engines.
A ªwasted sparkº system is used on the 5.7L
engine combining paired, or dual-firing coils, and 2
spark plugs per cylinder. The coils and spark plugs
are connected with paired, secondary high-voltage
cables.
Each cylinder is equipped with 1 dual-output coil.
Meaning one coil mounts directly over one of the
dual spark plugs for 1 high-voltage output. A second
high-voltage output is supplied directly from the
same coil (using a plug cable) to one of the dual
spark plugs on a corresponding (paired) cylinder on
the opposite cylinder bank.
Each coil fires 2 spark plugs simultaneously on
each of the cylinder banks (one cylinder on compres-
sion stroke and one cylinder on exhaust stroke).
EXAMPLE :When the #1 cylinder is on compression
stroke and ready for spark, the #1 coil will fire one of
the dual spark plugs on the #1 cylinder (directly
below the coil). The other dual spark plug on the #1
cylinder will be fired by the #6 coil. At the same
time, the #1 coil will fire a ªwasted sparkº to one of
the dual spark plugs at the #6 cylinder as coil #6 also
fires a ªwasted sparkº to one of the dual spark plugs
at the #6 cylinder.
The firing order is paired at cylinders 1/6, 2/3, 4/7,
5/8. Basic cylinder firing order is 1±8±4±3±6±5±7±2.
Battery voltage is supplied to all of the ignition
coils positive terminals from the ASD relay. If the
PCM does not see a signal from the crankshaft and
camshaft sensors (indicating the ignition key is ON
but the engine is not running), it will shut down the
ASD circuit.
Base ignition timing is not adjustable on the
5.7L V-8 engine.By controlling the coil ground cir-
cuits, the PCM is able to set the base timing and
adjust the ignition timing advance. This is done to
meet changing engine operating conditions.
The PCM adjusts ignition timing based on inputs it
receives from:
²The engine coolant temperature sensor
²The crankshaft position sensor (engine speed)²The camshaft position sensor (crankshaft posi-
tion)
²The manifold absolute pressure (MAP) sensor
²The throttle position sensor
²Transmission gear selection
REMOVAL
3.7L V-6
An individual ignition coil is used for each spark
plug (Fig. 15). The coil fits into machined holes in the
cylinder head. A mounting stud/nut secures each coil
to the top of the intake manifold (Fig. 16). The bot-
tom of the coil is equipped with a rubber boot to seal
the spark plug to the coil. Inside each rubber boot is
a spring. The spring is used for a mechanical contact
between the coil and the top of the spark plug. These
rubber boots and springs are a permanent part of the
coil and are not serviced separately. An o-ring (Fig.
15) is used to seal the coil at the opening into the cyl-
inder head.
(1) Depending on which coil is being removed, the
throttle body air intake tube or intake box may need
to be removed to gain access to coil.
(2) Disconnect electrical connector from coil by
pushing downward on release lock on top of connec-
tor and pull connector from coil.
(3) Clean area at base of coil with compressed air
before removal.
(4) Remove coil mounting nut from mounting stud
(Fig. 16).
(5) Carefully pull up coil from cylinder head open-
ing with a slight twisting action.
(6) Remove coil from vehicle.
4.7L V-8
An individual ignition coil is used for each spark
plug (Fig. 15). The coil fits into machined holes in the
cylinder head. A mounting stud/nut secures each coil
to the top of the intake manifold (Fig. 17). The bot-
tom of the coil is equipped with a rubber boot to seal
the spark plug to the coil. Inside each rubber boot is
a spring. The spring is used for a mechanical contact
between the coil and the top of the spark plug. These
rubber boots and springs are a permanent part of the
coil and are not serviced separately. An o-ring (Fig.
15) is used to seal the coil at the opening into the cyl-
inder head.
(1) Depending on which coil is being removed, the
throttle body air intake tube or intake box may need
to be removed to gain access to coil.
(2) Disconnect electrical connector (Fig. 17) from
coil by pushing downward on release lock on top of
connector and pull connector from coil.
(3) Clean area at base of coil with compressed air
before removal.
DRIGNITION CONTROL 8I - 13
IGNITION COIL (Continued)

(4) Remove coil mounting nut from mounting stud
(Fig. 17).
(5) Carefully pull up coil from cylinder head open-
ing with a slight twisting action.
(6) Remove coil from vehicle.
5.7L V-8
Before removing or disconnecting any spark plug
cables, note their original position. Remove cables
one-at-a-time. To prevent ignition crossfire, spark
plug cablesMUSTbe placed in cable tray (routing
loom) into their original position.
An individual ignition coil (Fig. 18) is used at each
cylinder. The coil mounts to the top of the valve cover
with 2 bolts (Fig. 19). The bottom of the coil is
equipped with a rubber boot to seal the spark plug to
the coil. Inside each rubber boot is a spring. The
spring is used for a mechanical contact between the
coil and the top of the spark plug.
(1) Depending on which coil is being removed, the
throttle body air intake tube or intake box may need
to be removed to gain access to coil.
(2) Unlock electrical connector (Fig. 19) by moving
slide lock first. Press on release lock (Fig. 19) while
pulling electrical connector from coil.
(3) Disconnect secondary high-voltage cable from
coil with a twisting action.
(4) Clean area at base of coil with compressed air
before removal.
(5) Remove 2 mounting bolts (note that mounting
bolts are retained to coil).
(6) Carefully pull up coil from cylinder head open-
ing with a slight twisting action.
(7) Remove coil from vehicle.
(8) Before installing spark plug cables to either the
spark plugs or coils, or before installing a coil to a
spark plug, apply dielectric grease to inside of boots.
INSTALLATION
3.7L V-6
(1) Using compressed air, blow out any dirt or con-
taminants from around top of spark plug.
(2) Check condition of coil o-ring and replace as
necessary. To aid in coil installation, apply silicone to
coil o-ring.
(3) Position ignition coil into cylinder head opening
and push onto spark plug. Do this while guiding coil
base over mounting stud.
(4) Install coil mounting stud nut. Refer to torque
specifications.
(5) Connect electrical connector to coil by snapping
into position.
(6) If necessary, install throttle body air tube.
4.7L V-8
(1) Using compressed air, blow out any dirt or con-
taminants from around top of spark plug.
(2) Check condition of coil o-ring and replace as
necessary. To aid in coil installation, apply silicone to
coil o-ring.
(3) Position ignition coil into cylinder head opening
and push onto spark plug. Do this while guiding coil
base over mounting stud.
(4) Install coil mounting stud nut. Refer to torque
specifications.
(5) Connect electrical connector to coil by snapping
into position.
(6) If necessary, install throttle body air tube.
5.7L V-8
(1) Using compressed air, blow out any dirt or con-
taminants from around top of spark plug.
(2) Before installing spark plug cables to either the
spark plugs or coils, or before installing a coil to a
spark plug, apply dielectric grease to inside of boots.
(3) Position ignition coil into cylinder head opening
and push onto spark plug. Twist coil into position.
(4) Install 2 coil mounting bolts. Refer to torque
specifications.
(5) Connect electrical connector to coil by snapping
into position.
(6) Install cable to coil. To prevent ignition cross-
fire, spark plug cablesMUSTbe placed in cable tray
(routing loom) into their original position. Refer to
Spark Plug Cable Removal for a graphic.
(7) If necessary, install throttle body air tube.
KNOCK SENSOR
DESCRIPTION
The sensors are used only with 3.7L V-6, 4.7L V-8
and 5.7L V-8 engines. On 3.7L V-6 and 4.7L V-8
engines, the 2 knock sensors are bolted into the cyl-
inder block under the intake manifold.
On 5.7L V-8 engines, 2 knock sensors are also
used. These are bolted into each side of the cylinder
block (outside) under the exhaust manifold.
OPERATION
3.7L V-6 / 4.7L V-8 / 5.7L V-8 Engines Only
Two knock sensors are used; one for each cylinder
bank. When the knock sensor detects a knock in one
of the cylinders on the corresponding bank, it sends
an input signal to the Powertrain Control Module
(PCM). In response, the PCM retards ignition timing
for all cylinders by a scheduled amount.
8I - 14 IGNITION CONTROLDR
IGNITION COIL (Continued)

SPARK PLUG OVERHEATING
Overheating is indicated by a white or gray center
electrode insulator that also appears blistered (Fig.
29). The increase in electrode gap will be consider-
ably in excess of 0.001 inch per 2000 miles of opera-
tion. This suggests that a plug with a cooler heat
range rating should be used. Over advanced ignition
timing, detonation and cooling system malfunctions
can also cause spark plug overheating.
REMOVAL
3.7L V-6
Each individual spark plug is located under each
ignition coil. Each individual ignition coil must be
removed to gain access to each spark plug. Refer to
Ignition Coil Removal/Installation.(1) Remove necessary air filter tubing at throttle
body.
(2) Prior to removing ignition coil, spray com-
pressed air around coil base at cylinder head.
(3) Prior to removing spark plug, spray com-
pressed air into cylinder head opening. This will help
prevent foreign material from entering combustion
chamber.
(4) Remove spark plug from cylinder head using a
quality socket with a rubber or foam insert. Also
check condition of ignition coil o-ring and replace as
necessary.
(5) Inspect spark plug condition. Refer to Diagnos-
tics and Testing - Spark Plug Conditions.
4.7L V-8
Each individual spark plug is located under each
ignition coil. Each individual ignition coil must be
removed to gain access to each spark plug. Refer to
Ignition Coil Removal/Installation.
(1) Remove necessary air filter tubing at throttle
body.
(2) Prior to removing ignition coil, spray com-
pressed air around coil base at cylinder head.
(3) Prior to removing spark plug, spray com-
pressed air into cylinder head opening. This will help
prevent foreign material from entering combustion
chamber.
(4) Remove spark plug from cylinder head using a
quality socket with a rubber or foam insert. Also
check condition of ignition coil o-ring and replace as
necessary.
(5) Inspect spark plug condition. Refer to Diagnos-
tics and Testing - Spark Plug Conditions.
5.7L V-8
Eight of the 16 spark plugs are located under an
ignition coil; the other 8 are not. If spark plug being
Fig. 27 CHIPPED ELECTRODE INSULATOR
1 - GROUND ELECTRODE
2 - CENTER ELECTRODE
3 - CHIPPED INSULATOR
Fig. 28 PREIGNITION DAMAGE
1 - GROUND ELECTRODE STARTING TO DISSOLVE
2 - CENTER ELECTRODE DISSOLVED
Fig. 29 SPARK PLUG OVERHEATING
1 - BLISTERED WHITE OR GRAY COLORED INSULATOR
DRIGNITION CONTROL 8I - 19
SPARK PLUG (Continued)

removed is under coil, coil must be removed to gain
access to spark plug. Refer to Ignition Coil Removal/
Installation and observe all CAUTIONS and WARN-
INGS.
Before removing or disconnecting any spark plug
cables, note their original position. Remove cables
one-at-a-time. To prevent ignition crossfire, spark
plug cablesMUSTbe placed in cable tray (routing
loom) into their original position. Refer to Spark Plug
Cable Removal for a graphic.
Before installing spark plug cables to either the
spark plugs or coils, apply dielectric grease to inside
of boots.
(1) Remove necessary air filter tubing at throttle
body.
(2) Prior to removing ignition coil (if coil removal
is necessary), spray compressed air around coil base
at cylinder head cover.
(3) Prior to removing spark plug, spray com-
pressed air into cylinder head opening. This will help
prevent foreign material from entering combustion
chamber.
(4) Remove spark plug from cylinder head using a
quality socket with a rubber or foam insert.
(5) Inspect spark plug condition. Refer to Diagnos-
tics and Testing - Spark Plug Conditions.
CLEANING
CLEANING AND ADJUSTMENT
The plugs may be cleaned using commercially
available spark plug cleaning equipment. After clean-
ing, file center electrode flat with a small point file or
jewelers file before adjusting gap.
CAUTION: Never use a motorized wire wheel brush
to clean spark plugs. Metallic deposits will remain
on spark plug insulator and will cause plug misfire.
Adjust spark plug gap with a gap gauging tool
(Fig. 30).
INSTALLATION
3.7L V-6
Special care should be taken when installing spark
plugs into the cylinder head spark plug wells. Be
sure the plugs do not drop into the plug wells as elec-
trodes can be damaged.
Always tighten spark plugs to the specified torque.
Over tightening can cause distortion resulting in a
change in the spark plug gap or a cracked porcelain
insulator.
(1) Start the spark plug into the cylinder head by
hand to avoid cross threading.(2) Tighten spark plugs. Refer to torque specifica-
tions.
(3) Before installing ignition coil(s), check condi-
tion of coil o-ring and replace as necessary. To aid in
coil installation, apply silicone to coil o-ring.
(4) Install ignition coil(s). Refer to Ignition Coil
Removal/Installation.
4.7L V-8
CAUTION: The 4.7L V±8 engine is equipped with
copper core ground electrode spark plugs. They
must be replaced with the same type/number spark
plug as the original. If another spark plug is substi-
tuted, pre-ignition will result.
Special care should be taken when installing spark
plugs into the cylinder head spark plug wells. Be
sure the plugs do not drop into the plug wells as elec-
trodes can be damaged.
Always tighten spark plugs to the specified torque.
Over tightening can cause distortion resulting in a
change in the spark plug gap or a cracked porcelain
insulator.
(1) Start the spark plug into the cylinder head by
hand to avoid cross threading.
(2) Tighten spark plugs. Refer to torque specifica-
tions.
(3) Before installing ignition coil(s), check condi-
tion of coil o-ring and replace as necessary. To aid in
coil installation, apply silicone to coil o-ring.
Fig. 30 SETTING SPARK PLUG GAP - TYPICAL
1 - GAUGE TOOL
2 - SPARK PLUG
8I - 20 IGNITION CONTROLDR
SPARK PLUG (Continued)

(4) Install ignition coil(s). Refer to Ignition Coil
Removal/Installation.
5.7L V-8
(1) Special care should be taken when installing
spark plugs into the cylinder head spark plug wells.
Be sure the plugs do not drop into the plug wells as
electrodes can be damaged.
(2) Start the spark plug into cylinder head by
hand to avoid cross threading aluminum threads. To
aid in installation, attach a piece of rubber hose, or
an old spark plug boot to spark plug.
(3) The 5.7L V-8 is equipped with torque critical
design spark plugs. Do not exceed 15 ft. lbs. torque.
Tighten spark plugs. Refer to torque specifications.
(4) Before installing spark plug cables to either the
spark plugs or coils, apply dielectric grease to inside
of boots.
(5) To prevent ignition crossfire, spark plug cables
MUSTbe placed in cable tray (routing loom) into
their original position. Refer to Spark Plug Cable
Removal for a graphic.
(6) Install ignition coil(s) to necessary spark plugs.
Refer to Ignition Coil Installation.
(7) Install spark plug cables to remaining spark
plugs. Remember to apply dielectric grease to inside
of boots.
IGNITION COIL CAPACITOR
DESCRIPTION
One coil capacitor is used. It is located in the right-
rear section of the engine compartment.
OPERATION
The coil capacitor(s) help dampen the amount of
conducted electrical noise to the camshaft position
sensor, crankshaft position sensor, and throttle posi-
tion sensor. This noise is generated on the 12V sup-
ply wire to the ignition coils and fuel injectors.
REMOVAL
The coil capacitor is located in the right-rear sec-
tion of the engine compartment. It is attached with a
mounting stud and nut.
(1) Disconnect electrical connector at capacitor
(Fig. 31).
(2) Remove mounting nut and remove ground
strap.
(3) Remove capacitor.
INSTALLATION
(1) Position capacitor to mounting stud.
(2) Position ground strap to mounting stud.
(3) Tighten nut to 7 N´m (60 in. lbs.) torque.
(4) Connect electrical connector to coil capacitor.
SPARK PLUG CABLE
DESCRIPTION
Spark plug cables are sometimes referred to as sec-
ondary ignition wires, or secondary ignition cables.
Plug cables are used only on the 5.7L V-8 engine.
OPERATION
The spark plug cables transfer electrical current
from the ignition coil(s) and/or distributor, to individ-
ual spark plugs at each cylinder. The resistive spark
plug cables are of nonmetallic construction. The
cables provide suppression of radio frequency emis-
sions from the ignition system.
Plug cables are used only on the 5.7L V-8 engine.
Fig. 31 CAPACITOR LOCATION
1 - COIL CAPACITOR
2 - MOUNTING STUD
3 - GROUND STRAP
4 - MOUNTING NUT
5 - ELEC. CONNECT.
DRIGNITION CONTROL 8I - 21
SPARK PLUG (Continued)

REMOVAL
5.7L V-8
Spark plug cables on the 5.7L engine are paired on
cylinders 1/6, 2/3, 4/7 and 5/8. Before removing or
disconnecting any spark plug cables, note their orig-
inal position (Fig. 32). Remove cables one-at-a-time.
To prevent ignition crossfire, spark plug cables
MUSTbe placed in cable tray (routing loom) into
their original position. The cable retention clips (Fig.
32) must also be securly locked.
Before installing spark plug cables to either the
spark plugs or coils, apply dielectric grease to inside
of boots.
If cable tray removal is necessary, release the 4
tray-to-manifold retention clips (Fig. 32).
INSTALLATION
Install cables into the proper engine cylinder firing
order sequence. Refer to Specifications.
When replacing the spark plug and coil cables,
route the cables correctly and secure them in the
proper retainers. Failure to route the cables properly
may cause the radio to reproduce ignition noise. It
could also cause cross-ignition of the plugs, or, may
short-circuit the cables to ground.
When installing new cables, make sure a positive
connection is made. A snap should be felt when a
good connection is made.
5.7L V-8
Refer to Spark Plug Cable Removal for
information.
Fig. 32 5.7L SPARK PLUG CABLE ROUTING
1 - #8 COIL-TO- #5 SPARK PLUG (MARKED 5/8) 7 - CABLE TRAY
2 - #5 COIL-TO- #8 SPARK PLUG (MARKED 5/8) 8 - CLIPS (SPARK PLUG CABLE-TO-TRAY- RETENTION)
3 - #7 COIL-TO- #4 SPARK PLUG (MARKED 4/7) 9 - #2 COIL-TO- #3 SPARK PLUG (MARKED 2/3)
4 - #3 COIL-TO- #2 SPARK PLUG (MARKED 2/3) 10 - #6 COIL-TO- #1 SPARK PLUG (MARKED 1/6)
5 - #1 COIL-TO- #6 SPARK PLUG (MARKED 1/6) 11 - #4 COIL-TO- #7 SPARK PLUG (MARKED 4/7)
6 - CLIPS (TRAY-TO-MANIFOLD RETENTION)
8I - 22 IGNITION CONTROLDR
SPARK PLUG CABLE (Continued)