C1 connector DODGE RAM 2003 Service User Guide

DESCRIPTION N´m Ft. Lbs. In. Lbs.
RWAL Valve
Brake Line Fittings19 Ð 170
Rear Wheel Speed Sensor
Mounting Bolt24 Ð 200
FRONT WHEEL SPEED
SENSOR
DESCRIPTION
The ABS brake system uses 3 wheel speed sensors.
A sensor is mounted to each front hub/bearings. The
third sensor is mounted on top of the rear axle dif-
ferential housing.
OPERATION
The Wheel Speed Sensor consists of a magnet sur-
rounded by windings from a single strand of wire.
The sensor sends a small AC signal to the CAB. This
signal is generated by magnetic induction. The mag-
netic induction is created when a toothed sensor ring
(exciter ring or tone wheel) passes the stationary
magnetic WSS.
When the ring gear is rotated, the exciter ring
passes the tip of the WSS. As the exciter ring tooth
approaches the tip of the WSS, the magnetic lines of
force expand, causing the magnetic field to cut across
the sensor's windings. This, in turn causes current to
flow through the WSS circuit (Fig. 1) in one direc-
tion. When the exciter ring tooth moves away from
the sensor tip, the magnetic lines of force collapse
cutting the winding in the opposite direction. This
causes the current to flow in the opposite direction.
Every time a tooth of the exciter ring passes the tip
of the WSS, an AC signal is generated. Each AC sig-
nal (positive to negative signal or sinewave) is inter-
preted by the CAB. It then compares the frequency of
the sinewave to a time value to calculate vehicle
speed. The CAB continues to monitor the frequency
to determine a deceleration rate that would indicate
a possible wheel-locking tendency.
The signal strength of any magnetic induction sen-
sor is directly affected by:
²Magnetic field strength; the stronger the mag-
netic field, the stronger the signal
²Number of windings in the sensor; more wind-
ings provide a stronger signal
²Exciter ring speed; the faster the exciter ring/
tone wheel rotates, the stronger the signal will be
²Distance between the exciter ring teeth and
WSS; the closer the WSS is to the exciter ring/tone
wheel, the stronger the signal will be
The rear WSS is not adjustable. A clearance speci-
fication has been established for manufacturing toler-ances. If the clearance is not within these
specifications, then either the WSS or other compo-
nents may be damaged. The clearance between the
WSS and the exciter ring is 0.005 ± 0.050 in.
The assembly plant performs a ªRolls Testº on
every vehicle that leaves the assembly plant. One of
the test performed is a test of the WSS. To properly
test the sensor, the assembly plant connects test
equipment to the Data Link Connector (DLC). This
connector is located to the right of the steering col-
umn and attached to the lower portion of the instru-
ment panel (Fig. 2). The rolls test terminal is spliced
to the WSS circuit. The vehicle is then driven on a
set of rollers and the WSS output is monitored for
proper operation.
REMOVAL
(1) Remove the front rotor (Refer to 5 - BRAKES/
HYDRAULIC/MECHANICAL/ROTORS - REMOV-
AL).
(2) Remove the wheel speed sensor mounting bolt
from the hub. (Fig. 3)
Fig. 1 Operation of the Wheel Speed Sensor
1 - MAGNETIC CORE
2 - CAB
3 - AIR GAP
4 - EXCITER RING
5 - COIL
DRBRAKES - ABS 5 - 41
BRAKES - ABS (Continued)

(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)

then opens the outlet valve, which also opens the
return circuit to the accumulators. Fluid pressure is
allowed to bleed off (decrease) as needed to prevent
wheel lock.
Once the period of high wheel slip has ended, the
CAB closes the outlet valve and begins a pressure
increase or hold cycle as needed.
PRESSURE HOLD
Both solenoid valves are closed in the pressure
hold cycle but only the inlet valve is energized. Fluid
apply pressure in the control channel is maintained
at a constant rate. The CAB maintains the hold cycle
until sensor inputs indicate a pressure change is nec-
essary.
PRESSURE INCREASE
The inlet valve is open and the outlet valve is
closed during the pressure increase cycle. The pres-
sure increase cycle is used to reapply thew brakes.
This cycle controls re-application of fluid apply pres-
sure.
REMOVAL
(1) Install a prop rod on the brake pedal to keep
pressure on the brake system.
(2) Disconnect the battery cables from the battery.
(3) Remove the battery.
(4) Disconnect the two electrical harness connec-
tors (Fig. 5).
(5) Remove the five brake lines from the HCU
(Fig. 5).
(6) Remove HCU/CAB mounting bolts and remove
the HCU/CAB (Fig. 5).
INSTALLATION
NOTE: If the CAB is being replaced with a new CAB
is must be reprogrammed with the use of a DRB III.
(1) Install HCU/CAB on the mounts and Tighten
the bolts to 15N´m (11 ft. lbs.) (Fig. 5).
(2) Install the five brake lines to the HCU and
tighten to 19 N´m (170 in. lbs.) (Fig. 5).
(3) Install the two electrical harness connectors to
the HCU/CAB and push down on the release to
secure the connectors.
(4) Install the battery.
(5) Install the battery cables to the battery.
(6) Remove the prop rod on the brake pedal.
(7) Bleed ABS brake system (Refer to 5 - BRAKES
- STANDARD PROCEDURE).
RWAL VALVE
DESCRIPTION
Rear Wheel Antilock (RWAL) brake system is stan-
dard equipment on 1500 series vehicles. The RWAL
brake system is designed to prevent rear wheel
lock-up on virtually all types of road surfaces. RWAL
braking is desirable because a vehicle which is
stopped without locking the rear wheels will retain
directional stability. This allows the driver to retain
greater control of the vehicle during braking.
The valve is located on the drivers side inner
fender under the hood. The valve modulates hydrau-
lic pressure to the rear brakes.
The RWAL components include:
²RWAL Valve
²Controller Antilock brake (CAB)
²Rear Wheel Speed Sensor (WSS)
OPERATION
When the brakes are applied, hydraulic fluid is
routed from the master cylinder's secondary circuit to
the RWAL valve. From there hydraulic fluid is routed
to the rear brakes. The Controller Antilock Brake
(CAB) contains an Electronic Variable Brake Propor-
tioning (EVBP) control algorithm, which proportions
the applied braking force to the rear wheels during
braking. The EVBP function of the RWAL system
takes the place of a conventional hydraulic propor-
tioning valve. The CAB monitors the rear wheel
speed through the rear wheel speed sensor and cal-
culates an estimated vehicle deceleration. When an
established deceleration threshold is exceeded, an
isolation valve is closed to hold the applied brake
pressure to the rear brakes constant. Upon further
increases in the estimated vehicle deceleration, the
isolation valve is selectively opened to increase rear
Fig. 5 HYDRAULIC CONTROL UNIT
1 - HYDRAULIC CONTROL UNIT
2 - MOUNTING BOLTS
5 - 44 BRAKES - ABSDR
HCU (HYDRAULIC CONTROL UNIT) (Continued)

brake pressure in proportion to the front brake pres-
sure. If impending rear wheel lock-up is sensed, the
CAB signals the RWAL valve to modulate hydraulic
brake pressure to the rear wheels to prevent lock-up.
NORMAL BRAKING Since the RWAL valve also
performs the EVBP or proportioning function, vehicle
deceleration under normal braking may be sufficient
to trigger the EVBP function of the RWAL system
without full RWAL activity as would normally occur
during an impending rear wheel lock-up. As previ-
ously mentioned, the isolation valve is selectively
closed and opened to increase rear brake pressure in
proportion to the front brake pressure under EVBP
control. Slight brake pedal pulsations may be noticed
as the isolation valve is opened.
REMOVAL
(1) Install a prop rod on the brake pedal to keep
pressure on the brake system.
(2) Disconnect the battery cables from the battery.
(3) Remove the battery.
(4) Disconnect the electrical harness connector
(Fig. 6).
(5) Remove the brake lines from the rwal valve
(Fig. 6).
(6) Remove rwal valve mounting nuts and remove
the rwal valve (Fig. 6).
INSTALLATION
(1) Install rwal valve and Tighten the nuts to 15
N´m (11 ft. lbs.) (Fig. 6).(2) Install the brake lines to the rwal valve and
tighten to 19 N´m (170 in. lbs.) (Fig. 6).
(3) Install the electrical harness connector to the
rwal valve and secure the connector.
(4) Install the battery.
(5) Install the battery cables to the battery.
(6) Remove the prop rod on the brake pedal.
(7) Bleed ABS brake system (Refer to 5 - BRAKES
- STANDARD PROCEDURE).
Fig. 6 RWAL VALVE
1 - RWAL VALVE
2 - MOUNTING NUTS
DRBRAKES - ABS 5 - 45
RWAL VALVE (Continued)

(3) Install clutch disc, pressure plate and trans-
mission.
LINKAGE
REMOVAL
CAUTION: The hydraulic linkage has a quick dis-
connect at the slave cylinder. This fitting should
never be disconnected or tampered with. Once the
hydraulic line is connected to the slave cylinder, it
should never be disconnected.
(1) Raise and support vehicle.
(2) Remove nuts attaching slave cylinder to studs
on clutch housing (Fig. 20).
(3) Remove slave cylinder from clutch housing.
(4) Remove plastic clip securing the hydraulic line
to the dash panel from the lower dash panel flange.
(5) Remove plastic clip securing hydraulic line to
the dash panel from the upper dash panel stud.
(6) Lower vehicle.
(7) Disconnect clutch pedal interlock switch wires
(Fig. 21).
(8) Remove clutch master cylinder rod pin.
(9) Verify that cap on clutch master cylinder reser-
voir is tight. This will avoid spillage during removal.
(10) Remove clutch master cylinder nuts holding
the to the dash panel.(11) Remove clutch cylinders, reservoir and con-
necting lines from vehicle.
INSTALLATION
(1) Position cylinders and connecting line in vehi-
cle engine compartment. Position clutch hydraulic
line against the dash panel and behind all engine
hoses and wiring.
(2) Apply a light coating of grease to the inside
diameter of the master cylinder push rod eye.
(3) Install clutch master cylinder on dash panel
and tighten clutch master cylinder nuts to 28 N´m
(21 ft. lbs.).
(4) Install clutch master cylinder push rod pin.
(5) Connect clutch pedal position interlock switch
wires.
Fig. 19 PILOT BEARING
1 - PILOT BEARING
2 - ALIGNMENT TOOL
3 - LETTER SIDE MUST FACE TRANSMISSION
Fig. 20 SLAVE CYLINDER
1 - MOUNTING NUTS
2 - SLAVE CYLINDER
Fig. 21 CLUTCH MASTER CYLINDER
1 - MASTER CYLINDER
2 - INTERLOCK CONNECTOR
3 - ROD PIN
DRCLUTCH 6 - 13
PILOT BEARING (Continued)

(6) Install plastic clip securing hydraulic line to
the dash panel into the lower dash panel flange.
(7) Install plastic clip securing hydraulic line to
the dash panel onto the upper dash panel stud.
(8) Raise vehicle.
(9) Install slave cylinder and verify cylinder rod is
properly seated in release lever.
(10) Install and tighten slave cylinder nuts to 23
N´m (17 ft. lbs.).
(11) Ifnewclutch linkage is being installed, con-
nect the clutch hydraulic line to the clutch slave cyl-
inder.
CAUTION: Once the clutch hydraulic line is con-
nected to the slave cylinder, it should never be dis-
connected.
(12) Lower vehicle.
(13) Operate linkage several times to verify proper
operation.
CLUTCH PEDAL POSITION
SWITCH
DESCRIPTION
A clutch pedal position (interlock) switch is
mounted on the clutch master cylinder push rod (Fig.
22). The switch is actuated by clutch pedal move-
ment.
OPERATION
The clutch pedal position switch is used to prevent
starter motor engagement unless the clutch pedal is
depressed.
An input from this switch is also used to either
shut down and/or prevent operation of the speed con-
trol system when the clutch pedal is depressed.
The position switch is an integral part of the clutch
master cylinder push rod and is not serviced sepa-
rately.
DIAGNOSIS AND TESTING
(1) Locate clutch switch 2-wire electrical connector.
This will be the test point. This connector is attached
to pedal support bracket located under instrument
panel to left of clutch pedal (Fig. 23). Disconnect wir-
ing at this point.
(2) Check for switch continuity with an ohmmeter
while operating clutch pedal up and down. Continu-
ity should be broken and reapplied each time pedal is
pressed.
(3) If continuity is not present, or is always
present at any pedal position, replace switch. Switch
is not serviced separately. Replace clutch master
cylinder.
Fig. 22 LOCATION, CLUTCH PEDAL POSITION
SWITCH
1 - CLUTCH MASTER CYLINDER
2 - CLUTCH PEDAL POSITION SWITCH
Fig. 23 CLUTCH SWITCH TEST POINT
1 - PEDAL SUPPORT BRACKET
2 - ELECTRICAL CONNECTOR
6 - 14 CLUTCHDR
LINKAGE (Continued)

COOLING SYSTEM DIAGNOSIS CHART
CONDITION POSSIBLE CAUSES CORRECTION
TEMPERATURE GAUGE
READS LOW1. Has a Diagnostic Trouble
Code (DTC) been set indicating
a stuck open thermostat?1. (Refer to 25 - EMISSIONS CONTROL -
DESCRIPTION) for On-Board Diagnostics
and DTC information. Replace thermostat
if necessary.
2. Is the temperature sending
unit connected?2. Check the temperature sensor
connector. (Refer to 8 - ELECTRICAL/
INSTRUMENT CLUSTER - SCHEMATIC -
ELECTRICAL) Repair connector if
necessary.
3. Is the temperature gauge
operating OK?3. Check gauge operation. (Refer to 8 -
ELECTRICAL/INSTRUMENT CLUSTER/
ENGINE TEMPERATURE GAUGE -
DESCRIPTION). Repair as necessary.
4. Coolant level low in cold
ambient temperatures
accompanied with poor heater
performance.4. Check coolant level in the coolant
reserve/overflow tank or degas bottle and
the radiator. Inspect system for leaks.
Repair leaks as necessary. Refer to the
Coolant section of the manual text for
WARNINGS and CAUTIONS associated
with removing the radiator cap.
5. Improper operation of internal
heater doors or heater controls.5. Inspect heater and repair as necessary.
(Refer to 24 - HEATING & AIR
CONDITIONING - DIAGNOSIS AND
TESTING) for procedures.
DRCOOLING 7 - 11
COOLING (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

(4) Using a suitable size socket, loosen and remove
the block heater element (Fig. 10).
INSTALLATION
(1) Clean and inspect the threads in the cylinder
block.
(2) Coat heater element threads with Mopart
Thread Sealer with Teflon.
(3) Screw block heater into cylinder block and
tighten to 43 N´m (32 ft. lbs.).
(4) Connect block heater cord and tighten retain-
ing cap.
(5) Fill cooling system with recommended coolant
(Refer to 7 - COOLING - STANDARD PROCE-
DURE).
(6) Start and warm the engine.
(7) Check block heater for leaks.
ENGINE COOLANT
TEMPERATURE SENSOR
DESCRIPTION
The Engine Coolant Temperature (ECT) sensor is
used to sense engine coolant temperature. The sensor
protrudes into an engine water jacket.
The ECT sensor is a two-wire Negative Thermal
Coefficient (NTC) sensor. Meaning, as engine coolant
temperature increases, resistance (voltage) in the
sensor decreases. As temperature decreases, resis-
tance (voltage) in the sensor increases.
OPERATION
At key-on, the Powertrain Control Module (PCM)
sends out a regulated 5 volt signal to the ECT sensor.
The PCM then monitors the signal as it passes
through the ECT sensor to the sensor ground (sensor
return).When the engine is cold, the PCM will operate in
Open Loop cycle. It will demand slightly richer air-
fuel mixtures and higher idle speeds. This is done
until normal operating temperatures are reached.
The PCM uses inputs from the ECT sensor for the
following calculations:
²for engine coolant temperature gauge operation
through CCD or PCI (J1850) communications
²Injector pulse-width
²Spark-advance curves
²ASD relay shut-down times
²Idle Air Control (IAC) motor key-on steps
²Pulse-width prime-shot during cranking
²O2 sensor closed loop times
²Purge solenoid on/off times
²EGR solenoid on/off times (if equipped)
²Leak Detection Pump operation (if equipped)
²Radiator fan relay on/off times (if equipped)
²Target idle speed
REMOVAL
3.7L V-6
The Engine Coolant Temperature (ECT) sensor on
the 3.7L engine is installed into a water jacket at
front of intake manifold near rear of generator (Fig.
11).
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 intake manifold.
4.7L V-8
WARNING: HOT, PRESSURIZED COOLANT CAN
CAUSE INJURY BY SCALDING. COOLING SYSTEM
MUST BE PARTIALLY DRAINED BEFORE REMOV-
ING THE ENGINE COOLANT TEMPERATURE (ECT)
SENSOR.
The Engine Coolant Temperature (ECT) sensor on
the 4.7L V-8 engine is located near the front of the
intake manifold (Fig. 12).
(1) Partially drain the cooling system. Refer to 7,
COOLING.
(2) Disconnect the electrical connector from the
ECT sensor.
(3) Remove the sensor from the intake manifold.
Fig. 10 Block Heater-Diesel Engine
1 - BLOCK HEATER
7 - 44 ENGINEDR
ENGINE BLOCK HEATER - 5.9L DIESEL (Continued)