1998 DODGE RAM 1500 4 wheel drive

CONNECTOR NAME/NUMBER COLOR LOCATION FIG.
Glove Box Lamp and Switch BK At Glove Box 35, 39
Governor Pressure Sensor BK Left Rear of Transmission N/S
Hands Free Module Right Instrument Panel 39
Headlamp Switch BK Left Side of Instrument Panel 32, 35, 38
Headlamp-Left BL At Headlamp 23, 28, 29
Headlamp-Right BL At Headlamp 1, 21, 26
Heated Seat Cushion - Driver BL Under Driver Seat N/S
Heated Seat Cushion - Passenger BL Under Passenger Seat N/S
Heated Seat Switch-Driver RD Center of Instrument Panel 33, 35, 36
Heated Seat Switch-Passenger BL Center of Instrument Panel 33, 35, 36
Horn Switch WT In Steering Wheel N/S
Horn-High Note BK Left Front Fender 23, 28, 29
Horn-Low Note BK Left Front Fender 23, 29
Idle Air Control Motor BK On Throttle Body 6
Ignition Coil GY Left Rear of Engine N/S
Ignition Switch BK Steering Column 31
Inlet Air Temperature/Pressure
SensorBK Right Side Engine 10
Input Speed Sensor BK At Transmission 15, 16
Instrument Cluster C1 GY Rear of Instrument Cluster 35
Instrument Cluster C2 GY Rear of Instrument Cluster 35
Instrument Cluster C3 WT Rear of Instrument Cluster 35
Intake Air Heater Relay Right Engine Compartment 2
Intake Air Temperature/Manifold
Absolute Pressure Sensor (Diesel)BK Left rear Engine N/S
Intake Air Temperature Sensor BK On Intake Manifold 5
Integrated Power Module C1 BK Left Front Fender 26, 28
Integrated Power Module C2 WT Left Front Fender 26, 28
Integrated Power Module C3 GR Left Front Fender 26, 28
Integrated Power Module C4 WT Left Front Fender 26, 28
Integrated Power Module C5 BK Left Front Fender 26, 28
Integrated Power Module C6 BK Left Front Fender 25, 26, 28
Integrated Power Module C7 GY Left Front Fender 26, 28
Integrated Power Module FCM BK In IPM N/S
Knock Sensor BK Left Rear of Engine 5, 7, 9
License Lamp-Left BK At Rear Bumper 50, 51
License Lamp-Right BK At Rear Bumper 50, 51
Lift Pump Motor BK Near T/O for WIF Sensor N/S
Line Pressure Sensor BK Right Rear of Transmission 15, 18
Lumbar Motor-Driver DK GY At Driver Seat N/S
Lumbar Motor-Passenger BK At Passenger Seat N/S
Manifold Absolute Pressure Sensor GY Left Front of Intake Manifold 6
Mode Door Actuator 1 BK Right Side of HVAC N/S
DR8W-91 CONNECTOR/GROUND/SPLICE LOCATION 8W - 91 - 5
CONNECTOR/GROUND/SPLICE LOCATION (Continued)

CONNECTOR NAME/NUMBER COLOR LOCATION FIG.
PTO Switch Near G107 N/S
Radio C1 (Base) GY Rear of Radio 35, 36
Radio C1 (Premium) BK Rear of Radio 36
Radio C2 (Premium) BK Rear of Radio 36
Radio Antenna - At Antenna Base 37
Radio Antenna Cable - Right Kick Panel 36, 37
Recirculation Door Actuator BK Right Side of HVAC N/S
Red Brake Warning Indicator
SwitchBK Near Master Cylinder 22, 25, 29
Remote Radio Switch-Left BK At Steering Wheel N/S
Remote Radio Switch-Right BK At Steering Wheel N/S
Seat Belt Pretensioner-Left YL Left B-Pillar 44, 46
Seat Belt Pretensioner-Right YL Right B-Pillar 45, 47
Seat Belt Switch-Driver DK GY Left B-Pillar N/S
Seat Belt Tension Reducer
(Standard Cab)YL Left B-Pillar 44
Seat Heater Interface Module GN Under Driver Seat N/S
Sentry Key Immobilizer Module BK On Steering Column 30
Side Marker - Left Front (Dual
Wheels)BK Front of Left Rear Fender 52
Side Marker - Left Rear (Dual
Wheels)BK Rear of Left Rear Fender 52
Side Marker - Right Front (Dual
Wheels)BK Front of Right Rear Fender 52
Side Marker - Right Rear (Dual
Wheels)BK Rear of Right Rear Fender 52
Speaker-Center Instrument Panel WT Center of Instrument Panel 35, 36
Speaker-Left Front Door WT In Left Front Door 41
Speaker-Left Instrument Panel BK Left Side of Instrument Panel 35, 38
Speaker-Left Rear (Standard Cab) WT In Lower Left B-Pillar 44
Speaker-Left Rear Door (Quad
Cab)WT In Left Rear Door 43
Speaker-Right Front Door WT In Right Front Door 42
Speaker-Right Instrument Panel BK Right Side of Instrument Panel 35, 39
Speaker-Right Rear (Standard
Cab)BK In Lower Right B-Pillar 45
Speaker-Right Rear Door (Quad
Cab)BK In Right Rear Door 43
Speed Control Servo BK Left Front Side of Engine
Compartment23, 25
Speed Control Switch - Left
(Except ETC)GN Steering Wheel N/S
Speed Control Switch - Right
(Except ETC)GN Steering Wheel N/S
Speed Control Switch-Left (ETC) WT At Steering Wheel N/S
DR8W-91 CONNECTOR/GROUND/SPLICE LOCATION 8W - 91 - 7
CONNECTOR/GROUND/SPLICE LOCATION (Continued)

CONNECTOR NAME/NUMBER COLOR LOCATION FIG.
Speed Control Switch-Right (ETC) WT At Steering Wheel N/S
Starter Solenoid Left Engine 23
Tail/Stop/Turn Signal Lamp-Left BK At Lamp 50, 51
Tail/Stop/Turn Signal Lamp-Right BK At Lamp 50, 51
Throttle Position Sensor NAT Throttle Body 6
Trailer Tow Connector BK At Trailer Hitch 51
Trailer Tow Connector-Add On BK At Trailer Hitch 51, 53
Transfer Case Control Module C1 BK Left Side of Instrument Panel 35, 38
Transfer Case Control Module C2 GY Left Side of Instrument Panel 35, 38
Transfer Case Control Module C3 BK Left Side of Instrument Panel 35, 38
Transfer Case Mode Sensor BK Left Front Side of Transfer Case 13, 14, 16, 20
Transfer Case Position Sensor BK Front Middle of Transfer Case 20
Transfer Case Selector Switch BK Center of Instrument Panel 11, 12, 33, 35, 36
Transfer Case Shift Motor BK Left Rear of Transmission 13, 14, 20
Transmission Range Sensor BK Left side of Transmission 11, 14
Transmission Solenoid Assembly BK Left Side of Transmission 14, 11
Transmission Solenoid/TRS
Assembly (3.7L/4.7L)BK Left Side of Transmission 15, 16
Underhood Lamp BK Underside of Hood 29
Vacuum Pump (Diesel) Right Rear Engine Compartment 21
Vistronic Fan Drive Front Engine Compartment 28
Washer Fluid Level Switch BK At Reservoir 21, 23, 26, 28
Washer Pump Motor-Front BK At Washer Fluid Reservoir 21, 23, 26, 28
Water In Fuel Sensor (Diesel) BK Right Side Engine 10
Wheel Speed Sensor-Left Front BK Left Rear Lower Side of Engine
Compartment22, 29
Wheel Speed Sensor-Rear BK Right Rear of Body 51
Wheel Speed Sensor-Right Front GY Right Rear Lower Side of Engine
Compartment21
Wiper Motor-Front BK Left Side of Cowl 22, 25
8W - 91 - 8 8W-91 CONNECTOR/GROUND/SPLICE LOCATIONDR
CONNECTOR/GROUND/SPLICE LOCATION (Continued)

(6) Air ingested into oil due to broken or cracked
oil pump pick up.
(7) Worn valve guides.
(8) Rocker arm ears contacting valve spring
retainer.
(9) Rocker arm loose, adjuster stuck or at maxi-
mum extension and still leaves lash in the system.
(10) Oil leak or excessive cam bore wear in cylin-
der head.
(11) Faulty lash adjuster.
a. Check lash adjusters for sponginess while
installed in cylinder head and cam on camshaft at
base circle. Depress part of rocker arm over adjuster.
Normal adjusters should feel very firm. Spongy
adjusters can be bottomed out easily.
b. Remove suspected lash adjusters, and replace.
c. Before installation, make sure adjusters are at
least partially full of oil. This can be verified by little
or no plunger travel when lash adjuster is depressed.
REMOVAL
(1) Disconnect battery negative cable.
(2) Raise the vehicle on a hoist.
(3) Disconnect the exhaust pipe at the right side
exhaust manifold.
(4) Drain the engine coolant(Refer to 7 - COOL-
ING - STANDARD PROCEDURE).
(5) Lower the vehicle.
(6) Remove the intake manifold(Refer to 9 -
ENGINE/MANIFOLDS/INTAKE MANIFOLD -
REMOVAL).
(7) Remove the cylinder head cover(Refer to 9 -
ENGINE/CYLINDER HEAD - REMOVAL).
(8) Remove the fan shroud(Refer to 7 - COOLING/
ENGINE/RADIATOR FAN - REMOVAL).
(9) Remove oil fill housing from cylinder head.
(10) Remove accessory drive belt(Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
REMOVAL).
(11) Rotate the crankshaft until the damper timing
mark is aligned with TDC indicator mark.
(12) Verify the V6 mark on the camshaft sprocket
is at the 12 o'clock position. Rotate the crankshaft
one turn if necessary.
(13) Remove the crankshaft damper(Refer to 9 -
ENGINE/ENGINE BLOCK/VIBRATION DAMPER -
REMOVAL).
(14) Remove the timing chain cover(Refer to 9 -
ENGINE/VALVE TIMING/TIMING BELT / CHAIN
COVER(S) - REMOVAL).
(15) Lock the secondary timing chains to the idler
sprocket using Special Tool 8429 Timing Chain Hold-
ing Fixture.NOTE: Mark the secondary timing chain prior to
removal to aid in installation.
(16) Mark the secondary timing chain, one link on
each side of the V6 mark on the camshaft drive gear.
(17) Remove the right side secondary chain ten-
sioner(Refer to 9 - ENGINE/VALVE TIMING/TIM-
ING BELT/CHAIN AND SPROCKETS - REMOVAL).
(18) Remove the cylinder head access plug.
(19) Remove the right side secondary chain
guide(Refer to 9 - ENGINE/VALVE TIMING/TIMING
BELT/CHAIN AND SPROCKETS - REMOVAL).
CAUTION: The nut on the right side camshaft
sprocket should not be removed for any reason, as
the sprocket and camshaft sensor target wheel is
serviced as an assembly. If the nut was removed,
torque nut to 5 N´m (44 in. lbs.).
(20) Remove the retaining bolt and the camshaft
drive gear.
CAUTION: Do not allow the engine to rotate. severe
damage to the valve train can occur.
CAUTION: Do not overlook the four smaller bolts at
the front of the cylinder head. Do not attempt to
remove the cylinder head without removing these
four bolts.
CAUTION: Do not hold or pry on the camshaft tar-
get wheel for any reason. A damaged target wheel
can result in a vehicle no start condition.
NOTE: The cylinder head is attached to the cylinder
block with twelve bolts.
(21) Remove the cylinder head retaining bolts.
(22) Remove the cylinder head and gasket. Discard
the gasket.
CAUTION: Do not lay the cylinder head on its gas-
ket sealing surface, do to the design of the cylinder
head gasket any distortion to the cylinder head
sealing surface may prevent the gasket from prop-
erly sealing resulting in leaks.
DRENGINE - 3.7L 9 - 33
CYLINDER HEAD - RIGHT (Continued)

CAUTION: The nut on the right side camshaft
sprocket should not be removed for any reason, as
the sprocket and camshaft sensor target wheel is
serviced as an assembly. If the nut was removed,
torque nut to 5 NM ( 60 in. lbs.).
(7) Position the secondary chain onto the camshaft
drive gear, making sure one marked chain link is on
either side of the V6 mark on the gear then using
Special Tool 8428 Camshaft Wrench, position the
gear onto the camshaft.
CAUTION: Remove excess oil from camshaft
sprocket retaining bolt before reinstalling bolt. Fail-
ure to do so may cause over-torquing of bolt result-
ing in bolt failure.
(8) Install the camshaft drive gear retaining bolt.
(9) Install the right side secondary chain guide(Re-
fer to 9 - ENGINE/VALVE TIMING/TIMING BELT/
CHAIN AND SPROCKETS - INSTALLATION).
(10) Install the cylinder head access plug.
(11) Re-set and install the right side secondary
chain tensioner(Refer to 9 - ENGINE/VALVE TIM-
ING/TIMING BELT/CHAIN AND SPROCKETS -
INSTALLATION).
(12) Remove Special Tool 8429.
(13) Install the timing chain cover(Refer to 9 -
ENGINE/VALVE TIMING/TIMING BELT / CHAIN
COVER(S) - REMOVAL).
(14) Install the crankshaft damper(Refer to 9 -
ENGINE/ENGINE BLOCK/VIBRATION DAMPER -
INSTALLATION). Tighten damper bolt 175 N´m (130
Ft. Lbs.).
(15) Install accessory drive belt(Refer to 7 - COOL-
ING/ACCESSORY DRIVE/DRIVE BELTS - INSTAL-
LATION).
(16) Install the fan shroud(Refer to 7 - COOLING/
ENGINE/RADIATOR FAN - INSTALLATION).
(17) Install the cylinder head cover(Refer to 9 -
ENGINE/CYLINDER HEAD/CYLINDER HEAD
COVER(S) - INSTALLATION).
(18) Install the intake manifold(Refer to 9 -
ENGINE/MANIFOLDS/INTAKE MANIFOLD -
INSTALLATION).
(19) Install oil fill housing onto cylinder head.
(20) Refill the cooling system(Refer to 7 - COOL-
ING - STANDARD PROCEDURE).
(21) Raise the vehicle.
(22) Install the exhaust pipe onto the right
exhaust manifold.
(23) Lower the vehicle.
(24) Reconnect battery negative cable.
(25) Start the engine and check for leaks.CAMSHAFT(S)
DESCRIPTION
The camshafts consist of powdered metal steel
lobes which are sinter-bonded to a steel tube. Four
bearing journals are machined into the camshaft.
Camshaft end play is controlled by two thrust walls
that border the nose piece journal. Engine oil enters
the hollow camshafts at the third journal and lubri-
cates every intake lobe rocker through a drilled pas-
sage in the intake lobe.
REMOVAL
CAUTION: When the timing chain is removed and
the cylinder heads are still installed, DO NOT force-
fully rotate the camshafts or crankshaft indepen-
dently of each other. Severe valve and/or piston
damage can occur.
CAUTION: When removing the cam sprocket, timing
chains or camshaft, Failure to use special tool 8379
will result in hydraulic tensioner ratchet over exten-
sion, Requiring timing chain cover removal to re-set
the tensioner ratchet.
(1) Remove the cylinder head cover(Refer to 9 -
ENGINE/CYLINDER HEAD/CYLINDER HEAD
COVER(S) - REMOVAL).
(2) Set engine to TDC cylinder No. 1, camshaft
sprocket V6 marks at the 12 o'clock position.
(3) Mark one link on the secondary timing chain
on both sides of the V6 mark on the camshaft
sprocket to aid in installation.
CAUTION: Do not hold or pry on the camshaft tar-
get wheel for any reason, Severe damage will occur
to the target wheel. A damaged target wheel could
cause a vehicle no start condition.
(4) Loosen butDO NOTremove the camshaft
sprocket retaining bolt. Leave bolt snug against
sprocket.
NOTE: The timing chain tensioners must be
secured prior to removing the camshaft sprockets.
Failure to secure tensioners will allow the tension-
ers to extend, requiring timing chain cover removal
in order to reset tensioners.
CAUTION: Do not force wedge past the narrowest
point between the chain strands. Damage to the
tensioners may occur.
DRENGINE - 3.7L 9 - 35
CYLINDER HEAD - RIGHT (Continued)

VALVE TIMING
DESCRIPTION
The timing drive system has been designed to pro-
vide quiet performance and reliability to support a
non-free wheelingengine. Specifically the intake
valves are non-free wheeling and can be easily dam-
aged with forceful engine rotation if camshaft-to-
crankshaft timing is incorrect. The timing drive
system consists of a primary chain, two secondary
timing chain drives (Fig. 94) and a counterbalance
shaft drive.
OPERATION
The primary timing chain is a single inverted tooth
chain type. The primary chain drives the large 50
tooth idler sprocket directly from a 25 tooth crank-shaft sprocket. Primary chain motion is controlled by
a pivoting leaf spring tensioner arm and a fixed
guide. The arm and the guide both use nylon plastic
wear faces for low friction and long wear. The pri-
mary chain receives oil splash lubrication from the
secondary chain drive and designed oil pump leak-
age. The idler sprocket assembly connects the pri-
mary chain drive, secondary chain drives, and the
counterbalance shaft. The idler sprocket assembly
consists of two integral 26 tooth sprockets a 50 tooth
sprocket and a helical gear that is press-fit to the
assembly. The spline joint for the 50 tooth sprocket is
a non serviceable press fit anti rattle type. A spiral
ring is installed on the outboard side of the 50 tooth
sprocket to prevent spline disengagement. The idler
sprocket assembly spins on a stationary idler shaft.
The idler shaft is a light press-fit into the cylinder
Fig. 94 Timing Drive System
1 - RIGHT CAMSHAFT SPROCKET AND SECONDARY CHAIN
2 - SECONDARY TIMING CHAIN TENSIONER (LEFT AND RIGHT
SIDE NOT INTERCHANGEABLE)
3 - SECONDARY TENSIONER ARM
4 - LEFT CAMSHAFT SPROCKET AND SECONDARY CHAIN
5 - CHAIN GUIDE (LEFT AND RIGHT SIDE ARE NOT
INTERCHANGEABLE)6 - PRIMARY CHAIN
7 - IDLER SPROCKET
8 - CRANKSHAFT SPROCKET
9 - PRIMARY CHAIN TENSIONER
9 - 76 ENGINE - 3.7LDR

block. A large washer on the idler shaft bolt and the
rear flange of the idler shaft are used to control
sprocket thrust movement. Pressurized oil is routed
through the center of the idler shaft to provide lubri-
cation for the two bushings used in the idler sprocket
assembly.
There are two secondary drive chains, both are
roller type, one to drive the camshaft in each SOHC
cylinder head. There are no shaft speed changes in
the secondary chain drive system. Each secondary
chain drives a 26 tooth cam sprocket directly from
the 26 tooth sprocket on the idler sprocket assembly.
A fixed chain guide and a hydraulic oil damped ten-
sioner are used to maintain tension in each second-
ary chain system. The hydraulic tensioners for the
secondary chain systems are fed pressurized oil from
oil reservoir pockets in the block. Each tensioner
incorporates a controlled leak path through a device
known as a vent disc located in the nose of the piston
to manage chain loads. Each tensioner also has a
mechanical ratchet system that limits chain slack if
the tensioner piston bleeds down after engine shut
down. The tensioner arms and guides also utilize
nylon wear faces for low friction and long wear. The
secondary timing chains receive lubrication from a
small orifice in the tensioners. This orifice is pro-
tected from clogging by a fine mesh screen which is
located on the back of the hydraulic tensioners.
STANDARD PROCEDURE
MEASURING TIMING CHAIN WEAR
NOTE: This procedure must be performed with the
timing chain cover removed.
(1) Remove the timing chain cover (Refer to 9 -
ENGINE/VALVE TIMING/TIMING BELT/CHAIN
AND SPROCKETS - REMOVAL).
(2) To determine if the secondary timing chains
are worn, rotate the engine clockwise until maximum
tensioner piston extension is obtained. Measure the
distance between the secondary timing chain ten-
sioner housing and the step ledge on the piston. The
measurement at point (A) must be less than 15mm
(.5906 inches) (Fig. 95).
(3) If the measurement exceeds the specification
the secondary timing chains are worn and require
replacement (Refer to 9 - ENGINE/VALVE TIMING/
TIMING BELT/CHAIN AND SPROCKETS -
REMOVAL).
SERVICE PROCEDURE - TIMING VERIFICATION
CAUTION: The 3.7L is a non free-wheeling design
engine. Therefore, correct engine timing is critical.
NOTE: Components referred to as left hand or right
hand are as viewed from the drivers position inside
the vehicle.
NOTE: The blue link plates on the chains and the
dots on the camshaft drive sprockets may not line
up during the timing verification procedure. The
blue link plates are lined up with the sprocket dots
only when re-timing the complete timing drive.
Once the timing drive is rotated blue link-to-dot
alignment is no longer valid.
Engine base timing can be verified by the following
procedure:
(1) Remove the cylinder head covers. Refer to the
procedure in this section.
Fig. 95 Measuring Secondary Timing Chains For
Wear
1 - SECONDARY TENSIONER ARM
2 - SECONDARY CHAIN TENSIONER PISTON
DRENGINE - 3.7L 9 - 77
VALVE TIMING (Continued)

IDLER SHAFT
REMOVAL
(1) Remove the primary and secondary timing
chains and sprockets. Refer to procedure in this sec-
tion.
NOTE: To remove the idler shaft, it is necessary to
tap threads into the shaft, to install the removal
tool.
(2) Using a 12 mm X 1.75 tap, cut threads in the
idler shaft center bore.
(3) Cover the radiator core with a suitable cover.
CAUTION: Use care when removing the idler shaft,
Do not strike the radiator cooling fins with the slide
hammer.
(4) Using Special Tool 8517 Slide Hammer, remove
the idler shaft.
INSTALLATION
(1) Thoroughly clean the idler shaft bore.
(2) Position the idler shaft in the bore.
NOTE: The two lubrication holes in the idler shaft
do not require any special alignment.
NOTE: Before using the retaining bolt to install the
idler shaft, coat the threads and the pilot on the
idler shaft, with clean engine oil.
(3) Using the primary idler sprocket retaining bolt
and washer, carefully draw the idler shaft into the
bore until fully seated.
(4) Coat the idler shaft with clean engine oil.
(5) Install the timing chains and sprockets. Refer
to procedure in this section.
TIMING BELT / CHAIN
COVER(S)
REMOVAL
(1) Disconnect the battery negative cable.
(2) Drain cooling system (Refer to 7 - COOLING -
STANDARD PROCEDURE).
(3) Remove electric cooling fan and fan shroud
assembly.
(4) Remove fan and fan drive assembly (Refer to 7
- COOLING/ENGINE/FAN DRIVE VISCOUS
CLUTCH - REMOVAL).
(5) Disconnect both heater hoses at timing cover.
(6) Disconnect lower radiator hose at engine.(7) Remove accessory drive belt tensioner assembly
(Fig. 103).
(8) Remove crankshaft damper (Refer to 9 -
ENGINE/ENGINE BLOCK/VIBRATION DAMPER -
REMOVAL).
(9) Remove the generator (Refer to 8 - ELECTRI-
CAL/CHARGING/GENERATOR - REMOVAL).
(10) Remove A/C compressor (Refer to 24 - HEAT-
ING & AIR CONDITIONING/PLUMBING/A/C COM-
PRESSOR - REMOVAL).
CAUTION: The 3.7L engine uses an anerobic sealer
instead of a gasket to seal the front cover to the
engine block, from the factory. For service, MoparT
Engine RTV sealant must be substituted.
NOTE: It is not necessary to remove the water
pump for timing cover removal.
(11) Remove the bolts holding the timing cover to
engine block (Fig. 104).
(12) Remove the timing cover.
INSTALLATION
CAUTION: Do not use oil based liquids to clean tim-
ing cover or block surfaces. Use only rubbing alco-
hol, along with plastic or wooden scrapers. Use no
wire brushes or abrasive wheels or metal scrapers,
or damage to surfaces could result.
Fig. 103 ACCESSORY DRIVE BELT TENSIONER
1 - TENSIONER ASSEMBLY
2 - FASTENER TENSIONER TO FRONT COVER
DRENGINE - 3.7L 9 - 81