2003 DODGE RAM Wiring harness

(3) Remove the wheel speed sensor from the hub.
(4) Remove the wiring from the clips and discon-
nect the electrical connector.
INSTALLATION
(1) Install the wiring to the clips and Reconnect
the electrical connector.
(2) Install the wheel speed sensor to the hub.
(3) Install the wheel speed sensor mounting bolt to
the hub. Tighten the bolt to 21 N´m (190 in. lbs.).
(4) Install the front rotor and brake caliper assem-
bly (Refer to 5 - BRAKES/HYDRAULIC/MECHANI-
CAL/ROTORS - INSTALLATION).
REAR WHEEL SPEED SENSOR
DIAGNOSIS AND TESTING - REAR WHEEL
ANTILOCK
Diagnosis of base brake conditions which are
mechanical in nature should be performed first. This
includes brake noise, lack of power assist, parking
brake, or vehicle vibration during normal braking.
The RWAL brake system performs several self-
tests every time the ignition switch is turned on and
the vehicle is driven. The CAB monitors the system
inputs and outputs circuits to verify the system is
operating properly. If the CAB senses a malfunction
in the system it will set a DTC into memory and trig-
ger the warning lamp.
NOTE: The MDS or DRB III scan tool is used to
diagnose the RWAL system. For test procedures
refer to the Chassis Diagnostic Manual.
REMOVAL
(1) Raise the vehicle on a hoist.
(2) Remove the brake line mounting nut and
remove the brake line from the sensor stud.
(3) Remove the mounting stud from the sensor and
shield (Fig. 4).
(4) Remove the sensor and shield from the differ-
ential housing.
(5) Disconnect the sensor wire harness and remove
the sensor.
Fig. 2 Data Link Connector - Typical
1 - 16±WAY DATA LINK CONNECTOR
Fig. 3 WHEEL SPEED SENSOR
1 - WHEEL SPEED SENSOR MOUNTING BOLT
2 - WHEEL SPEED SENSOR
3 - HUB/BEARING
Fig. 4 REAR WHEEL SPEED SENSOR
1 - WHEEL SPEED SENSOR
2 - MOUNTING BOLT
3 - AXLE HOUSING
5 - 42 BRAKES - ABSDR
FRONT WHEEL SPEED SENSOR (Continued)

INSTALLATION
(1) Connect the harness to the sensor.Be sure
the seal is securely in place between the sensor
and the wiring connector.
(2) Install the O-ring on the sensor (if removed).
(3) Insert the sensor in the differential housing.
(4) Install the sensor shield.
(5) Install the sensor mounting stud and tighten to
24 N´m (200 in. lbs.).
(6) Install the brake line on the sensor stud and
install the nut.
(7) Lower the vehicle.
TONE WHEEL
DIAGNOSIS AND TESTING - REAR WHEEL
SPEED SENSOR
Diagnosis of base brake conditions which are
mechanical in nature should be performed first. This
includes brake noise, lack of power assist, parking
brake, or vehicle vibration during normal braking.
The Antilock brake system performs several self-
tests every time the ignition switch is turned on and
the vehicle is driven. The CAB monitors the system
inputs and outputs circuits to verify the system is
operating properly. If the CAB senses a malfunction
in the system it will set a DTC into memory and trig-
ger the warning lamp.
NOTE: The MDS or DRB III scan tool is used to
diagnose the Antilock Brake system. For test proce-
dures refer to the Chassis Diagnostic Manual.
HYDRAULIC/MECHANICAL
DESCRIPTION - ELECTRONIC VARIABLE
BRAKE PROPORTIONING
Vehicles equipped with ABS use electronic variable
brake proportioning (EVBP) to balance front-to-rear
braking. The EVBP is used in place of a rear propor-
tioning valve. The EVBP system uses the ABS sys-
tem to control the slip of the rear wheels in partial
braking range. The braking force of the rear wheels
is controlled electronically by using the inlet and out-
let valves located in the integrated control unit
(ICU).
OPERATION - ELECTRONIC VARIABLE BRAKE
PROPORTIONING
EVBP is able to decrease, hold and increase rear
brake pressure without activating full ABS control.
Upon entry into EVBP the inlet valve for the rear
brake circuit is switched on so that the fluid supplyfrom the master cylinder is shut off. In order to
decrease the rear brake pressure, the outlet valve for
the rear brake circuit is pulsed. This allows fluid to
enter the low pressure accumulator (LPA) in the
hydraulic control unit (HCU) resulting in a drop in
fluid pressure to the rear brakes. In order to increase
the rear brake pressure, the outlet valve is switched
off and the inlet valve is pulsed. This increases the
pressure to the rear brakes.
The EVBP will remain functional during many
ABS fault modes. If both the red BRAKE and amber
ABS warning indicators are illuminated, the EVBP
may not be functioning.
HCU (HYDRAULIC CONTROL
UNIT)
DESCRIPTION
The HCU consists of a valve body, pump motor, low
pressure accumulators, inlet valves, outlet valves and
noise attenuators.
OPERATION
Accumulators in the valve body store extra fluid
released to the system for ABS mode operation. The
pump provides the fluid volume needed and is oper-
ated by a DC type motor. The motor is controlled by
the CAB.
The valves modulate brake pressure during
antilock braking and are controlled by the CAB.
The HCU provides three channel pressure control
to the front and rear brakes. One channel controls
the rear wheel brakes in tandem. The two remaining
channels control the front wheel brakes individually.
During antilock braking, the solenoid valves are
opened and closed as needed.
During normal braking, the HCU solenoid valves
and pump are not activated. The master cylinder and
power booster operate the same as a vehicle without
an ABS brake system.
NOTE: The three modes mentioned below do occur
but not necessarily in the order listed everytime.
During antilock braking, solenoid valve pressure
modulation occurs in three stages, pressure increase,
pressure hold, and pressure decrease. The valves are
all contained in the valve body portion of the HCU.
PRESSURE DECREASE
The outlet valve is opened and the inlet valve is
closed during the pressure decrease cycle.
A pressure decrease cycle is initiated when speed
sensor signals indicate high wheel slip at one or
more wheels. At this point, the CAB closes the inlet
DRBRAKES - ABS 5 - 43
REAR WHEEL SPEED SENSOR (Continued)

RADIATOR FAN - 5.9L DIESEL
REMOVAL
CAUTION: If the electronically controlled viscous
fan drive is replaced because of mechanical dam-
age, the cooling fan blades should also be
inspected. Inspect for fatigue cracks, or loose rivets
that could have resulted from excessive vibration.
Replace fan blade assembly if any of these condi-
tions are found. Also inspect wiring harness and
connectors for damage.
(1) Disconnect the battery negative cables.
(2) Remove the fan shroud lower half. by unsnap-
ping the fastening tabs.
CAUTION: Do not remove the fan pulley bolts. This
pulley is under spring tension.
(3) Disconnect electrical connector.
(4) The electronically controlled viscous fan drive/
fan blade assembly is attached (threaded) to the fan
hub shaft (Fig. 5). Remove the fan blade/fan drive
assembly from fan pulley by turning the mounting
nut counterclockwise (as viewed from front). Threads
on the viscous fan drive areRIGHT-HAND.A
Snap-On 36 MM Fan Wrench (number SP346 from
Snap-On Cummins Diesel Tool Set number 2017DSP)
can be used. Place a bar or screwdriver between the
fan pulley bolts to prevent pulley from rotating.
(5) Remove the fan shroud and the fan blade/vis-
cous drive as an assembly from vehicle from under
the vehicle.
(6) Remove fan blade-to-viscous fan drive mount-
ing bolts.
(7) Inspect the fan for cracks, loose or bent fan
blades.
CAUTION: Some engines equipped with serpentine
drive belts have reverse rotating fans and viscous
fan drives. Installation of the wrong fan or viscous
fan drive can result in engine overheating.
CLEANING
Clean the fan blades using a mild soap and water.
Do not use an abrasive to clean the blades.
INSPECTION
WARNING: DO NOT ATTEMPT TO BEND OR
STRAIGHTEN FAN BLADES IF FAN IS NOT WITHIN
SPECIFICATIONS.CAUTION: If fan blade assembly is replaced
because of mechanical damage, water pump and
viscous fan drive should also be inspected. These
components could have been damaged due to
excessive vibration.
(1) Remove fan blade assembly from viscous fan
drive unit (six bolts).
(2) Lay fan on a flat surface with leading edge fac-
ing down. With tip of blade touching flat surface,
replace fan if clearance between opposite blade and
surface is greater than 2.0 mm (.090 inch). Rocking
motion of opposite blades should not exceed 2.0 mm
(.090 inch). Test all blades in this manner.
(3) Inspect fan assembly for cracks, bends, or bro-
ken welds. Replace fan if any damage is found.
INSTALLATION
(1) Install fan blade assembly to electrically con-
trolled viscous fan drive. Tighten mounting bolts to
23 N´m (17 ft. lbs.) torque.
(2) Position the fan blade/viscous fan drive to the
vehicle as an assembly.
(3) Install viscous fan drive assembly on fan hub
shaft (Fig. 5). Tighten mounting nut to 33 N´m (24 ft.
lbs.) torque.
(4) Connect electrical connector.
Fig. 5 Fan Blade/Viscous Fan Drive
1 - ELECTRICAL CONNECTOR
2 - VISCOUS FAN DRIVE
3 - FAN BLADE
4 - BOLT
5 - FAN DRIVE
DRENGINE 7 - 41

(2) Disconnect the electrical connector from the
sensor.
(3) Remove the sensor from the cylinder head.
5.9L V-8 Gas
WARNING: HOT, PRESSURIZED COOLANT CAN
CAUSE INJURY BY SCALDING. COOLING SYSTEM
MUST BE PARTIALLY DRAINED BEFORE REMOV-
ING THE COOLANT TEMPERATURE SENSOR.
REFER TO GROUP 7, COOLING.
(1) Partially drain the cooling system. Refer to 7,
COOLING.
(2) Disconnect the electrical connector from the
sensor (Fig. 16).
(3)Engines with air conditioning:When
removing the connector from the sensor, do not pull
directly on the wiring harness. The connector is
snapped onto the sensor. It is not equipped with a
lock type tab.
(4) Remove the sensor from the intake manifold.
8.0L V-10
The Engine Coolant Temperature (ECT) sensor on
the 8.0L V-10 engine is threaded into the thermostat
housing (Fig. 17).
WARNING: HOT, PRESSURIZED COOLANT CAN
CAUSE INJURY BY SCALDING. COOLING SYSTEM
MUST BE PARTIALLY DRAINED BEFORE REMOV-
ING THE COOLANT TEMPERATURE SENSOR.
(1) Partially drain the cooling system.
(2) Disconnect the electrical connector from the
sensor.
(3) Remove the sensor from the cylinder head.
Fig. 14 ECT REMOVE / INSTALL 5.7L V-8
1 - FRONT OF INTAKE MANIFOLD
2 - ELECTRICAL CONNECTOR
3 - ECT SENSOR
Fig. 15 ECT LOCATION - 5.9L DIESEL
1 - THERMOSTAT HOUSING
2 - ELECTRICAL CONNECTOR
3 - ECT SENSOR
Fig. 16 ECT SENSOR - 5.9L V-8
1 - GENERATOR
2 - A/C COMPRESSOR
3 - ENGINE COOLANT TEMPERATURE SENSOR
4 - ELEC. CONN.
7 - 46 ENGINEDR
ENGINE COOLANT TEMPERATURE SENSOR (Continued)

OPERATION
The wax pellet is located in a sealed container at
the spring end of the thermostat. When heated, the
pellet expands, overcoming closing spring tension
and water pump pressure to force the valve to open.
DIAGNOSIS AND TESTINGÐTHERMOSTAT
ON-BOARD DIAGNOSTICS
Allgasoline powered modelsare equipped with
On-Board Diagnostics for certain cooling system com-
ponents. Refer to On-Board Diagnostics (OBD) in the
Diagnosis section of this group for additional infor-
mation. If the powertrain control module (PCM)
detects low engine coolant temperature, it will record
a Diagnostic Trouble Code (DTC) in the PCM mem-
ory. Do not change a thermostat for lack of heat as
indicated by the instrument panel gauge or by poor
heater performance unless a DTC is present. Refer to
the Diagnosis section of this group for other probable
causes.
The DTC can also be accessed through the
DRBIIItscan tool. Refer to the appropriate Power-
train Diagnostic Procedures information for diagnos-
tic information and operation of the DRBIIItscan
tool.
REMOVAL
WARNING: DO NOT LOOSEN THE RADIATOR
DRAINCOCK WITH THE COOLING SYSTEM HOT
AND PRESSURIZED. SERIOUS BURNS FROM THE
COOLANT CAN OCCUR.
Do not waste reusable coolant. If the solution is
clean, drain the coolant into a clean container for
reuse.
If the thermostat is being replaced, be sure that
the replacement is the specified thermostat for the
vehicle model and engine type.
Factory installed thermostat housings on 5.9L
engine is installed on a gasket with an anti-stick
coating. This will aid in gasket removal and clean-up.
(1) Disconnect the negative battery cable.
(2) Drain the cooling system until the coolant level
is below the thermostat (Refer to 7 - COOLING -
STANDARD PROCEDURE).
(3) Air Conditioned vehicles: Remove the support
bracket (generator mounting bracket-to-intake mani-
fold) located near the rear of the generator (Fig. 19).
NOTE: On air conditioning equipped vehicles, the
generator must be partially removed.
(4) Remove the accessory drive belt (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
REMOVAL) (Fig. 20).
(5) Remove the generator mounting bolts. Do not
remove any of the wiring at the generator. If
equipped with 4WD, unplug the 4WD indicator lamp
wiring harness (located near rear of generator).
(6) Remove the generator. Position the generator
to gain access for the thermostat gasket removal.
Fig. 18 Thermostat - 5.7L/5.9L Gas Powered
Engines
1 - THERMOSTAT HOUSING
2 - GASKET
3 - INTAKE MANIFOLD
4 - THERMOSTAT
5 - MACHINED GROOVE
Fig. 19 Generator Support Bracket ± 5.9L Engine
1 - IDLER PULLEY BUSHING
2 - A/C AND/OR GENERATOR MOUNTING BRACKET
3 - IDLER PULLEY
4 - SCREW AND WASHER
7 - 48 ENGINEDR
ENGINE COOLANT THERMOSTAT- 5.7L/5.9L (Continued)

WARNING: CONSTANT TENSION HOSE CLAMPS
ARE USED ON MOST COOLING SYSTEM HOSES.
WHEN REMOVING OR INSTALLING, USE ONLY
TOOLS DESIGNED FOR SERVICING THIS TYPE OF
CLAMP. ALWAYS WEAR SAFETY GLASSES WHEN
SERVICING CONSTANT TENSION CLAMPS.
CAUTION: A number or letter is stamped into the
tongue of the constant tension clamps (Fig. 21). If
replacement is necessary, use only an original
equipment clamp with a matching number, letter
and width.
(7) Remove the radiator upper hose clamp and
upper hose at the thermostat housing.
(8) Position the wiring harness (behind thermostat
housing) to gain access to the thermostat housing.
(9) Remove the thermostat housing mounting
bolts, thermostat housing, gasket and thermostat
(Fig. 22). Discard old gasket.
INSTALLATION
(1) Clean the mating areas of the intake manifold
and thermostat housing.
(2) Install the thermostat (spring side down) into
the recessed machined groove on the intake manifold
(Fig. 22).
(3) Install the gasket on the intake manifold and
over the thermostat (Fig. 22).(4) Position the thermostat housing to the intake
manifold.Note:The word FRONT stamped on hous-
ing (Fig. 23). For adequate clearance, thismustbe
placed towards the front of the vehicle. The housing
is slightly angled forward after the installation to the
intake manifold.
(5) Install the housing-to-intake manifold bolts.
Tighten the bolts to 23 N´m (200 in. lbs.).
Fig. 20 Automatic Belt Tensioner ± 5.9L Engines
1 - IDLER PULLEY
2 - TENSIONER
3 - FAN BLADE
Fig. 21 SPRING CLAMP SIZE LOCATION
1 - SPRING CLAMP SIZE LOCATION
Fig. 22 Thermostat ± 5.9L Engines
1 - THERMOSTAT HOUSING
2 - GASKET
3 - INTAKE MANIFOLD
4 - THERMOSTAT
5 - MACHINED GROOVE
DRENGINE 7 - 49
ENGINE COOLANT THERMOSTAT- 5.7L/5.9L (Continued)

INSPECTION
Visually inspect the water pump and replace if it
has any of the following conditions:
²The body is cracked or damaged
²Water leaks from the shaft seal. This is evident
by traces of coolant below the vent hole
²Loose or rough turning bearing.
²Impeller rubbing the pump body
INSTALLATION
(1) Install new O-ring seal in groove on water
pump (Fig. 51).
(2) Install water pump. Tighten mounting bolts to
24 N´m (18 ft. lbs.) torque.
(3) Install accessory drive belt. Refer to procedure
in this group.
(4) Install the bolt retaining the wiring harness
near top of water pump.
(5) Fill cooling system. Refer to Refilling Cooling
System in this section.
(6) Connect both battery cables.
(7) Start and warm the engine. Check for leaks.
WATER PUMP INLET TUBE -
5.9L
REMOVAL
REMOVAL - WATER PUMP BYPASS HOSE
WITH AIR CONDITIONING
If equipped with A/C, the generator and A/C com-
pressor along with their common mounting bracket
(Fig. 52) must be partially removed. Removing thegenerator or A/C compressor from their mounting
bracket is not necessary. Also, discharging the A/C
system is not necessary.Do notremove any refriger-
ant lines from A/C compressor.
WARNING: THE A/C SYSTEM IS UNDER PRESSURE
EVEN WITH THE ENGINE OFF. REFER TO REFRIG-
ERANT WARNINGS IN SECTION 24 - HEATING AND
AIR CONDITIONING.
(1) Disconnect the negative battery cable.
(2) Partially drain the cooling system (Refer to 7 -
COOLING - STANDARD PROCEDURE).Do not
waste reusable coolant. If the solution is clean, drain
the coolant into a clean container for reuse.
(3) Remove the upper radiator hose clamp at the
radiator. A special clamp tool must be used to remove
the constant tension clamps. Removethe hose at the
radiator.
(4) Unplug the wiring harness from the A/C com-
pressor.
(5) Remove the air cleaner assembly.
(6) Remove the accessory drive belt (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
REMOVAL).
(7) The drive belt idler pulley must be removed to
gain access to one of the A/C compressor/generator
bracket mounting bolts. Remove the idler pulley bolt
and remove idler pulley (Fig. 53).
(8) Remove the engine oil dipstick tube mounting
bolt at the side of the A/C-generator mounting
bracket.
(9) Disconnect the throttle body control cables.
Fig. 51 Pump O-ring Seal
1 - O-RING SEAL
2 - GROOVE
3 - WATER PUMP
Fig. 52 Generator - A/C Compressor Mounting
Bracket - Typical
7 - 68 ENGINEDR
WATER PUMP - 5.9L DIESEL (Continued)

CAUTION: A number or letter is stamped into the
tongue of the constant tension clamps. If replace-
ment is necessary, use only an original equipment
clamp with a matching number or letter and width.
(2) Loosen both of the bypass hose clamps and
position them to the center of the hose.
(3) Removethe hose from the vehicle.
INSTALLATION
INSTALLATION - WATER PUMP BYPASS HOSE
WITH AIR CONDITIONING
(1) Position the bypass hose clamps to the center
of the bypass hose.
(2) Install the bypass hose to the engine.
(3) Secure both of the hose clamps.
(4) Install the generator-A/C mounting bracket
assembly to the engine. Tighten bolt number 1 (Fig.
53) to 41 N´m (30 ft. lbs.). Tighten bolt number 2
(Fig. 53) to 28 N´m (20 ft. lbs.). Tighten bracket
mounting bolts (Fig. 53) (Fig. 53) to 40 N´m (30 ft.
lbs.).
(5) Install a new O-ring to the heater hose coolant
return tube. Coat the new O-ring with antifreeze
before installation.
(6) Install the coolant return tube and its mount-
ing bolt to the engine.
(7) Connect the throttle body control cables.
(8) Install the oil dipstick mounting bolt.
(9) Install the idler pulley. Tighten the bolt to 41
N´m (30 ft. lbs.) (Fig. 57).
(10) Install the drive belt (Refer to 7 - COOLING/
ACCESSORY DRIVE/DRIVE BELTS - INSTALLA-
TION).CAUTION: When installing the serpentine accessory
drive belt, the belt must be routed correctly. If not,
the engine may overheat due to the water pump
rotating in the wrong direction (Refer to 7 - COOL-
ING/ACCESSORY DRIVE/DRIVE BELTS - INSTALLA-
TION). The correct belt with the correct length must
be used.
(11) Install the air cleaner assembly.
(12) Install the upper radiator hose to the radiator.
(13) Connect the throttle cable to the clip at the
radiator fan shroud.
(14) Connect the wiring harness to the A/C com-
pressor.
(15) Fill the cooling system (Refer to 7 - COOLING
- STANDARD PROCEDURE).
(16) Start and warm the engine. Check for leaks.
INSTALLATION - WATER PUMP BYPASS HOSE
WITHOUT AIR CONDITIONING
(1) Position the bypass hose clamps to the center
of the bypass hose.
(2) Install the bypass hose tothe engine.
(3) Secure both of the hose clamps.
(4) Fill the cooling system (Refer to 7 - COOLING
- STANDARD PROCEDURE).
(5) Start and warm the engine. Check for leaks.
WATER PUMP - 5.7L
REMOVAL
(1) Disconnect negative battery cable.
(2) Drain coolant.
(3) Remove serpentine belt.
(4) Remove fan clutch assembly.
(5) Remove coolant fill bottle.
Fig. 56 Water Pump Bypass Hose - Typical
1 - WATER PUMP BYPASS HOSE
2 - FAN BLADE ASSEMBLY
3 - VISCOUS FAN DRIVE
4 - WATER PUMP AND PULLEY
Fig. 57 Tensioner Mounting
1 - DOWEL PIN HOLE
2 - TENSIONER MOUNTING BRACKET
7 - 70 ENGINEDR
WATER PUMP INLET TUBE - 5.9L (Continued)