Causes DODGE RAM 1500 1998 2.G Repair Manual

loaded pressure relief valve. This valve opens when
system pressure reaches the release range of 97-to-
124 kPa (14-to-18 psi).
A rubber gasket seals the radiator filler neck. This
is done to maintain vacuum during coolant cool-down
and to prevent leakage when system is under pres-
sure.
OPERATION
A vent valve in the center of the cap will remain
shut as long as the cooling system is pressurized. As
the coolant cools, it contracts and creates a vacuum
in the cooling system. This causes the vacuum valve
to open and coolant in the reserve/overflow container
to be drawn through the recovery hose connecting
the filler neck and reserve/overflow container. If the
vacuum valve is stuck shut, or the recovery hose is
kinked, radiator hoses will collapse on cool down.
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - RADIATOR
CAP-TO-FILLER NECK SEAL
The pressure cap upper gasket (seal) pressure
relief can be tested by removing overflow hose from
the radiator filler neck tube. Attach the hose of the
pressure tester tool 7700 (or equivalent) to the tube.
It will be necessary to disconnect hose from its
adapter for the filler neck. Pump air into radiator.
The pressure cap upper gasket should relieve at 69
to 124kPa (10 to 18 psi) and hold pressure at a min-
imum of 55 kPa (8 psi).
WARNING: THE WARNING WORDS, ºDO NOT OPEN
HOTº, ON RADIATOR PRESSURE CAP, ARE A
SAFETY PRECAUTION. WHEN HOT, PRESSURE
BUILDS UP IN COOLING SYSTEM. TO PREVENT
SCALDING OR INJURY, RADIATOR CAP SHOULD
NOT BE REMOVED WHILE SYSTEM IS HOT AND/OR
UNDER PRESSURE.
Do not remove the radiator cap at any timeexcept
for the following purposes:
²Check and adjust antifreeze freeze point.
²Refill the system with new antifreeze.
²Conducting service procedures.
²Checking for vacuum leaks.
WARNING: IF VEHICLE HAS BEEN RUN RECENTLY,
WAIT AT LEAST 15 MINUTES BEFORE REMOVING
RADIATOR CAP. WITH A RAG, SQUEEZE RADIATOR
UPPER HOSE TO CHECK IF SYSTEM IS UNDER
PRESSURE. PLACE A RAG OVER CAP AND WITH-
OUT PUSHING CAP DOWN, ROTATE IT COUNTER-
CLOCKWISE TO FIRST STOP. ALLOW FLUID TO
ESCAPE THROUGH THE COOLANT RESERVE/
OVERFLOW HOSE INTO RESERVE/OVERFLOW
TANK. SQUEEZE RADIATOR UPPER HOSE TO
DETERMINE WHEN PRESSURE HAS BEEN
RELEASED. WHEN COOLANT AND STEAM STOP
BEING PUSHED INTO TANK AND SYSTEM PRES-
SURE DROPS, REMOVE RADIATOR CAP COM-
PLETELY.
DIAGNOSIS AND TESTING - RADIATOR CAP
Remove the cap from the radiator. Be sure that the
sealing surfaces are clean. Moisten the rubber gasket
with water and install the cap on the pressure tester
7700 or an equivalent (Fig. 41).
Operate the tester pump to bring the pressure to
104 kPa (15 psi) on the gauge. If the pressure cap
fails to hold pressure of at least 97 kPa (14 psi)
replace the cap. Refer to the followingCAUTION.
Fig. 40 Radiator Pressure Cap - Typical
1 - FILLER NECK SEAL
2 - VACUUM VENT VALVE
3 - PRESSURE RATING
4 - PRESSURE VALVE
7 - 58 ENGINEDR
RADIATOR PRESSURE CAP (Continued)

The optional navigation radio system receives GPS
signals from up to eight satellites to display the posi-
tion and direction of the vehicle. Map information is
supplied through a DVD-ROM. An electronic gyro-
sensor and the vehicle's speed sensor enable the sys-
tem to display the present vehicle position even in
locations where GPS signals may be blocked.
When a destination is selected, the navigation sys-
tem uses information from the map to quickly calcu-
late a route. As the vehicle is driven along the chosen
route, the operator is guided with pictorial displays
and voice prompts. For complete operating instruc-
tions, refer to the manual included with the vehicle.
On vehicles that are equipped with the optional
remote radio switches, the Instrument Cluster
receives hard wired resistor multiplexed inputs from
the remote radio switches. The programming in the
Instrument Cluster allows it to process those inputs
and send the proper messages to the radio receiver
over the Programmable Communication Interface
(PCI) bus network to control the radio volume up or
down, station seek up or down, preset station
advance, and mode advance functions.DIAGNOSIS AND TESTING - AUDIO
Any diagnosis of the Audio system should
begin with the use of the DRB IIItdiagnostic
tool. For information on the use of the
DRB IIIt, refer to the appropriate Diagnostic
Service Manual.
Refer to the appropriate wiring information.
WARNING: DISABLE THE AIRBAG SYSTEM
BEFORE ATTEMPTING ANY STEERING WHEEL,
STEERING COLUMN, SEAT BELT TENSIONER, SIDE
AIRBAG, 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.
AUDIO SYSTEM DIAGNOSIS TABLE
CONDITION POSSIBLE CAUSES CORRECTION
NO AUDIO 1. Fuse faulty. 1. Check radio fuse and Ignition-Off Draw (IOD)
fuse in the Integrated Power Module (IPM).
Replace fuses, if required.
2. Radio/amplifier (if
equipped) connector faulty.2. Check for loose or corroded radio/amplifier
connector. Repair, if required.
3. Wiring faulty. 3. Check for shorted or open wires. Repair wiring,
if required.
4. Radio/amplifier (if
equipped) ground faulty.4. Check for continuity between radio chassis and
a known good ground. There should be
continuity. Repair ground, if required.
5. Radio/amplifier (if
equipped) faulty.5. Refer to appropriate Diagnostic Service
Manual.
6. Speakers faulty. 6. Replace speaker as necessary.
NO RADIO DISPLAY 1. Fuse faulty. 1. Check radio fuse and Ignition-Off Draw (IOD)
fuse in Integrated Power Module (IPM). Replace
fuses, if required.
2. Radio connector faulty. 2. Check for loose or corroded radio connector.
Repair, if required.
3. Wiring faulty. 3. Check for battery voltage at radio connector.
Repair wiring, if required.
4. Radio ground faulty. 4. Check for continuity between radio chassis and
a known good ground. There should be
continuity. Repair ground, if required.
5. Radio faulty. 5. Refer to appropriate Diagnostic Service
Manual.
8A - 2 AUDIO/VIDEODR
AUDIO (Continued)

CONDITION POSSIBLE CAUSES CORRECTION
CLOCK WILL NOT KEEP
SET TIME1. Fuse faulty. 1. Check Ignition-Off Draw (IOD) fuse in the
Integrated Power Module (IPM). Replace fuse, if
required.
2. Radio connector faulty. 2. Check for loose or corroded radio connector.
Repair, if required.
3. Wiring faulty. 3. Check for battery voltage at radio connector.
Repair wiring, if required.
4. Radio ground faulty. 4. Check for continuity between radio chassis and
a known good ground. There should be
continuity. Repair ground, if required.
5. Radio faulty. 5. Refer to appropriate Diagnostic Service
Manual.
POOR RADIO RECEPTION 1. Antenna faulty. 1. (Refer to 8 - ELECTRICAL/AUDIO/ANTENNA
BODY & CABLE - DIAGNOSIS AND TESTING).
2. Radio ground faulty. 2. Check for continuity between radio chassis and
a known good ground. There should be
continuity. Repair ground, if required.
3. Radio noise suppression
faulty.3. Repair or replace ground strap as necessary.
4. Radio faulty. 4. Refer to appropriate Diagnostic Service
Manual.
NO/POOR TAPE
OPERATION1. Faulty tape. 1. Insert known good tape and test operation.
2. Foreign objects behind
tape door.2. Remove foreign objects and test operation.
3. Dirty cassette tape head. 3. Clean head with Mopar Cassette Head
Cleaner.
4. Faulty tape deck. 4. Exchange or replace radio, if required.
NO COMPACT DISC
OPERATION1. Faulty CD. 1. Insert known good CD and test operation.
2. Foreign material on CD. 2. Clean CD and test operation.
3. Condensation on CD or
optics.3. Allow temperature of vehicle interior to stabilize
and test operation.
4. Faulty CD player. 4. Refer to appropriate Diagnostic Service
Manual.
AMPLIFIER
DESCRIPTION
The optional Infinity premium speaker system
includes a separate Infinity audio power amplifier.
The amplifier is a six channel unit and is rated at
240 total output watts. The amplifier is located
behind the glove box.
OPERATION
The power amplifier electronically increases the
frequency response of the normal audio signal output
from the radio amplifier in order to improve the
acoustic performance of the speakers. On vehiclesequipped with an amplifier, the amplifier section of
the radio becomes a pre-amplifier.
The amplifier receives audio signal inputs for
speaker channels from the radio, then sends ampli-
fied audio outputs through six separate channels
with dedicated feed and return circuits to the indi-
vidual speakers.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove glove box (Refer to 23 - BODY/IN-
STRUMENT PANEL/GLOVE BOX - REMOVAL).
DRAUDIO/VIDEO 8A - 3
AUDIO (Continued)

CONDITION POSSIBLE CAUSES CORRECTION
NO SEAT BELT WARNING
CHIME WITH SEAT BELT
UNBUCKLED, BUT OTHER
CHIME FEATURES OK1. Seat belt switch ground
circuit open.1. Check for continuity between the ground
circuit for the driver seat belt switch and a good
ground. Repair open ground circuit, if required.
2. Seat belt switch sense
circuit open.2. Check for continuity between the seat belt
switch sense circuit for the driver seat belt switch
and the instrument cluster connector. Repair the
open seat belt switch sense circuit, if required.
3. Faulty seat belt switch. 3. Check for continuity between the ground
circuit and the driver seat belt switch sense
circuit of the seat belt switch. There should be
continuity with the seat belt unbuckled. Replace
the faulty seat belt, if required.
SEAT BELT WARNING
CHIME WITH SEAT BELT
BUCKLED1. Seat belt switch sense
circuit shorted.1. With the driver seat belt switch and the
instrument cluster connector disconnected, there
should be no continuity between the seat belt
switch sense circuit and a good ground. Repair
the shorted seat belt switch sense circuit, if
required.
2. Faulty seat belt switch. 2. Check for continuity between the ground
circuit cavity and the seat belt switch sense
circuit of the driver seat belt switch. There should
be no continuity with the seat belt buckled.
Replace the faulty seat belt, if required.
NO KEY-IN IGNITION
WARNING CHIME, BUT
OTHER CHIME FEATURES
OK1. Driver door ajar switch
sense circuit open.1. Check for continuity between the driver door
ajar switch sense circuit connector and the
instrument cluster connector. Repair the open
driver door ajar switch sense circuit, if required.
2. Key-in ignition switch
sense circuit open.2. Check for continuity between the key-in
ignition switch sense circuit connector and
instrument cluster connector. Repair the open
key-in ignition switch sense circuit, if required.
3. Key-in ignition switch
ground circuit open.3. Check for continuity between the ground
circuit cavity of the ignition switch connector and
a good ground. Repair the open ground circuit, if
required
4. Faulty ignition switch. 4. Check for continuity between the ground
circuit terminal and the key-in ignition switch
sense circuit terminal in the ignition switch
connector. There should be continuity with a key
in the ignition lock cylinder. Replace the faulty
ignition switch, if required.
8B - 4 CHIME/BUZZERDR
CHIME WARNING SYSTEM (Continued)

CONDITION POSSIBLE CAUSES CORRECTION
1. Driver door ajar switch
sense circuit open.1. Check for continuity between the driver door
ajar switch sense circuit connector and the
instrument cluster connector. Repair the open
driver door ajar switch sense circuit, if required.
2. Headlamp switch signal
circuit open.2. Check for continuity between the headlamp
switch output circuit connector and the and the
instrument cluster connector. Repair the open
headlamp switch signal circuit, if required.
NO CHIMES AND OTHER
INSTRUMENT CLUSTER
FEATURES ERRATIC OR
DISABLED1. Instrument cluster ground
circuit(s) open.1. Check for continuity between the ground
circuits of the instrument cluster connector and a
good ground. Repair the open ground circuits(s),
if required.
2. Instrument cluster fused
B(+) circuit(s) open.2. Check for battery voltage at the B(+) circuits of
the instrument cluster connector. Repair the open
fused B(+) circuit(s), if required.
3. Instrument cluster fused
ignition switch output
(run-start) circuit open.3. With the ignition switch in the On position,
check for battery voltage at the fused ignition
switch output (run-start) circuit of the instrument
cluster connector. Repair the open fused ignition
switch output (run-start) circuit, if required.
4. Faulty instrument cluster. 4. Replace the faulty instrument cluster, if
required.
NO CHIMES, BUT ALL
OTHER INSTRUMENT
CLUSTER FEATURES OK1. Faulty instrument cluster. 1. Replace the faulty instrument cluster, if
required.
DRCHIME/BUZZER 8B - 5
CHIME WARNING SYSTEM (Continued)

BATTERY SYSTEM DIAGNOSIS
CONDITION POSSIBLE CAUSES CORRECTION
THE BATTERY SEEMS
WEAK OR DEAD WHEN
ATTEMPTING TO START
THE ENGINE.1. The electrical system
ignition-off draw is excessive.1. Refer to the IGNITION-OFF DRAW TEST
Standard Procedure for the proper test
procedures. Repair the excessive ignition-off
draw, as required.
2. The charging system is
faulty.2. Determine if the charging system is performing
to specifications. Refer to Charging System for
additional charging system diagnosis and testing
procedures. Repair the faulty charging system, as
required.
3. The battery is discharged. 3. Determine the battery state-of-charge using the
Micro 420 battery tester. Refer to the Standard
Procedures in this section for additional test
procedures. Charge the faulty battery, as
required.
4. The battery terminal
connections are loose or
corroded.4. Refer to Battery Cables for the proper battery
cable diagnosis and testing procedures. Clean
and tighten the battery terminal connections, as
required.
5. The battery has an
incorrect size or rating for
this vehicle.5. Refer to Battery System Specifications for the
proper size and rating. Replace an incorrect
battery, as required.
6. The battery is faulty. 6. Determine the battery cranking capacity using
the Micro 420 battery tester. Refer to the
Standard Procedures in this section for additional
test procedures. Replace the faulty battery, as
required.
7. The starting system is
faulty.7. Determine if the starting system is performing
to specifications. Refer to Starting System for the
proper starting system diagnosis and testing
procedures. Repair the faulty starting system, as
required.
8. The battery is physically
damaged.8. Inspect the battery for loose terminal posts or a
cracked and leaking case. Replace the damaged
battery, as required.
DRBATTERY SYSTEM 8F - 3
BATTERY SYSTEM (Continued)

BATTERY SYSTEM DIAGNOSIS
CONDITION POSSIBLE CAUSES CORRECTION
THE BATTERY STATE OF
CHARGE CANNOT BE
MAINTAINED.1. The battery has an
incorrect size or rating for
this vehicle.1. Refer to Battery System Specifications for the
proper specifications. Replace an incorrect
battery, as required.
2. The battery terminal
connections are loose or
corroded.2. Refer to Battery Cable for the proper cable
diagnosis and testing procedures. Clean and
tighten the battery terminal connections, as
required.
3. The electrical system
ignition-off draw is excessive.3. Refer to the IGNITION-OFF DRAW TEST
Standard Procedure for the proper test
procedures. Repair the faulty electrical system, as
required.
4. The battery is faulty. 4. Test the battery using the Micro 420 battery
tester. Refer to Standard Procedures for
additional test procedures. Replace the faulty
battery, as required.
5. The starting system is
faulty.5. Determine if the starting system is performing
to specifications. Refer to Starting System for the
proper starting system diagnosis and testing
procedures. Repair the faulty starting system, as
required.
6. The charging system is
faulty.6. Determine if the charging system is performing
to specifications. Refer to Charging System for
additional charging system diagnosis and testing
procedures. Repair the faulty charging system, as
required.
7. Electrical loads exceed the
output of the charging
system.7. Inspect the vehicle for aftermarket electrical
equipment which might cause excessive electrical
loads.
8. Slow driving or prolonged
idling with high-amperage
draw systems in use.8. Advise the vehicle operator, as required.
THE BATTERY WILL NOT
ACCEPT A CHARGE.1. The battery is faulty. 1. Test the battery using the Micro 420 battery
tester. Charge or replace the faulty battery, as
required.
ABNORMAL BATTERY DISCHARGING
Any of the following conditions can result in abnor-
mal battery discharging:
1. A faulty or incorrect charging system compo-
nent. Refer to Charging System for additional charg-
ing system diagnosis and testing procedures.
2. A faulty or incorrect battery. Use Micro 420 bat-
tery tester and refer to Battery System for additional
battery diagnosis and testing procedures.
3. A faulty circuit or component causing excessive
ignition-off draw.4. Electrical loads that exceed the output of the
charging system. This can be due to equipment
installed after manufacture, or repeated short trip
use.
5. A faulty or incorrect starting system component.
Refer to Starting System for the proper starting sys-
tem diagnosis and testing procedures.
6. Corroded or loose battery posts and/or terminal
clamps.
7. Slow driving speeds (heavy traffic conditions) or
prolonged idling, with high-amperage draw systems
in use.
8F - 4 BATTERY SYSTEMDR
BATTERY SYSTEM (Continued)

BATTERY CHARGING TIME TABLE
Charging
Amperage5 Amps10
Amps20 Amps
Open Circuit
VoltageHours Charging @ 21É C (70É
F)
12.25 to 12.49 6 hours 3 hours 1.5
hours
12.00 to 12.24 10 hours 5 hours 2.5
hours
10.00 to 11.99 14 hours 7 hours 3.5
hours
Below 10.00 18 hours 9 hours 4.5
hours
STANDARD PROCEDURE - BUILT-IN
INDICATOR TEST
If equipped, an indicator (hydrometer) built into
the top of the battery case provides visual informa-
tion for battery testing (Fig. 6). Like a hydrometer,
the built-in indicator measures the specific gravity of
the battery electrolyte. The specific gravity of the
electrolyte reveals the battery state-of-charge; how-
ever, it will not reveal the cranking capacity of the
battery. A load test must be performed to determine
the battery cranking capacity. Refer to Standard Pro-
cedures for the proper battery load test procedures.
Before testing, visually inspect the battery for any
damage (a cracked case or cover, loose posts, etc.)
that would cause the battery to be faulty. In order to
obtain correct indications from the built-in indicator,
it is important that the battery be level and have a
clean sight glass. Additional light may be required to
view the indicator.Do not use open flame as a
source of additional light.To read the built-in indicator, look into the sight
glass and note the color of the indication (Fig. 7). The
battery condition that each color indicates is
described in the following list:
²Green- Indicates 75% to 100% battery state-of-
charge. The battery is adequately charged for further
testing or return to service. If the starter will not
crank for a minimum of fifteen seconds with a fully-
charged battery, the battery must be load tested.
Refer to Standard Procedures for the proper battery
load test procedures.
²Black or Dark- Indicates 0% to 75% battery
state-of-charge. The battery is inadequately charged
and must be charged until a green indication is visi-
ble in the sight glass (12.4 volts or more), before the
battery is tested further or returned to service. Refer
to Standard Procedures for the proper battery charg-
ing procedures. Also refer to Diagnosis and Testing
for more information on the possible causes of the
discharged battery condition.
²Clear or Bright- Indicates a low battery elec-
trolyte level. The electrolyte level in the battery is
below the built-in indicator. A maintenance-free bat-
tery with non-removable cell caps must be replaced if
the electrolyte level is low. Water must be added to a
low-maintenance battery with removable cell caps
before it is charged. Refer to Standard Procedures for
the proper battery filling procedures. A low electro-
lyte level may be caused by an overcharging condi-
tion. Refer to Charging System for the proper
charging system diagnosis and testing procedures.
STANDARD PROCEDURE - OPEN-CIRCUIT
VOLTAGE TEST
A battery open-circuit voltage (no load) test will
show the approximate state-of-charge of a battery.
This test can be used in place of the hydrometer test
when a hydrometer is not available, or for mainte-
nance-free batteries with non-removable cell caps.
Before proceeding with this test, completely charge
the battery (Refer to 8 - ELECTRICAL/BATTERY
SYSTEM/BATTERY - STANDARD PROCEDURE).
Fig. 6 Built-In Indicator
1 - SIGHT GLASS
2 - BATTERY TOP
3 - GREEN BALL
4 - PLASTIC ROD
Fig. 7 Built-In Indicator Sight Glass Chart
8F - 10 BATTERY SYSTEMDR
BATTERY (Continued)

If the vehicle is equipped with an automatic trans-
mission, battery voltage is supplied through the low-
amperage control circuit to the coil battery terminal
of the starter relay when the ignition switch is
turned to the Start position. The park/neutral posi-
tion switch is installed in series between the starter
relay coil ground terminal and ground. This normally
open switch prevents the starter relay from being
energized and the starter motor from operating
unless the automatic transmission gear selector is in
the Neutral or Park positions.
When the starter relay coil is energized, the nor-
mally open relay contacts close. The relay contacts
connect the relay common feed terminal to the relay
normally open terminal. The closed relay contacts
energize the starter solenoid coil windings.
The energized solenoid pull-in coil pulls in the sole-
noid plunger. The solenoid plunger pulls the shift
lever in the starter motor. This engages the starter
overrunning clutch and pinion gear with the starter
ring gear.
As the solenoid plunger reaches the end of its
travel, the solenoid contact disc completes the high-
amperage starter feed circuit and energizes the sole-
noid plunger hold-in coil. Current now flows between
the solenoid battery terminal and the starter motor,
energizing the starter.Once the engine starts, the overrunning clutch pro-
tects the starter motor from damage by allowing the
starter pinion gear to spin faster than the pinion
shaft. When the ignition switch is released to the On
position, the starter relay coil is de-energized. This
causes the relay contacts to open. When the relay
contacts open, the starter solenoid plunger hold-in
coil is de-energized.
When the solenoid plunger hold-in coil is de-ener-
gized, the solenoid plunger return spring returns the
plunger to its relaxed position. This causes the con-
tact disc to open the starter feed circuit, and the shift
lever to disengage the overrunning clutch and pinion
gear from the starter ring gear.
DIAGNOSIS AND TESTING - STARTING
SYSTEM
The battery, starting, and charging systems oper-
ate in conjunction with one another, and must be
tested as a complete system. For correct starting/
charging system operation, all of the components
involved in these 3 systems must perform within
specifications.
Starting System Diagnosis
CONDITION POSSIBLE CAUSE CORRECTION
STARTER FAILS TO
OPERATE.1. Battery discharged or
faulty.1. Refer to Battery. Charge or replace battery, if required.
2. Starting circuit wiring
faulty.2. Refer to 8, Wiring Diagrams. Test and repair starter
feed and/or control circuits, if required.
3. Starter relay faulty. 3. Refer to Starter Relay in Diagnosis and Testing.
Replace starter relay if required.
4. Ignition switch faulty. 4. Refer to Ignition Switch and Key Lock Cylinder.
Replace ignition switch if required.
5. Clutch pedal position
switch faulty.5. Refer to Clutch Pedal Position Switch.
6. Park/Neutral position
switch faulty or
misadjusted.6. Refer to Park/Neutral Position Switch. Replace
park/neutral position switch if required.
7. Starter solenoid faulty. 7. Refer to Starter Motor. Replace starter motor assembly
if required.
8. Starter motor faulty. 8. If all other starting system components and circuits test
OK, replace starter motor.
DRSTARTING 8F - 27
STARTING (Continued)

CAMSHAFT POSITION SENSOR
DESCRIPTION
3.7L V-6
The Camshaft Position Sensor (CMP) on the 3.7L
6-cylinder engine is bolted to the right-front side of
the right cylinder head.
4.7L V-8
The Camshaft Position Sensor (CMP) on the 4.7L
V-8 engine is bolted to the right-front side of the
right cylinder head.
5.7L V-8
The Camshaft Position Sensor (CMP) on the 5.7L
V-8 engine is located below the generator on the tim-
ing chain / case cover on the right/front side of
engine.
5.9L Diesel
The Camshaft Position Sensor (CMP) on the 5.9L
diesel engine is located below the fuel injection
pump. It is bolted to the back of the timing gear
cover.
OPERATION
3.7L V-6
The Camshaft Position Sensor (CMP) sensor on the
3.7L V-6 engine contains a hall effect device referred
to as a sync signal generator. A rotating target wheel
(tonewheel) for the CMP is located at the front of the
camshaft for the right cylinder head (Fig. 6). This
sync signal generator detects notches located on a
tonewheel. As the tonewheel rotates, the notches
pass through the sync signal generator. The signal
from the CMP sensor is used in conjunction with the
Crankshaft Position Sensor (CKP) to differentiate
between fuel injection and spark events. It is also
used to synchronize the fuel injectors with their
respective cylinders.
When the leading edge of the tonewheel notch
enters the tip of the CMP, the interruption of mag-
netic field causes the voltage to switch high, result-
ing in a sync signal of approximately 5 volts.
When the trailing edge of the tonewheel notch
leaves then tip of the CMP, the change of the mag-
netic field causes the sync signal voltage to switch
low to 0 volts.
4.7L V-8
The CMP sensor on the 4.7L engine contains a hall
effect device called a sync signal generator to gener-
ate a fuel sync signal. This sync signal generator
detects notches located on a tonewheel. The tone-wheel is located at the front of the camshaft for the
right cylinder head (Fig. 7). As the tonewheel rotates,
the notches pass through the sync signal generator.
The pattern of the notches (viewed counter-clockwise
from front of engine) is: 1 notch, 2 notches, 3 notches,
3 notches, 2 notches 1 notch, 3 notches and 1 notch.
The signal from the CMP sensor is used in conjunc-
tion with the crankshaft position sensor to differenti-
ate between fuel injection and spark events. It is also
used to synchronize the fuel injectors with their
respective cylinders.
5.7L V-8
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.
The tonewheel is located at the front of the cam-
shaft (Fig. 8). As the tonewheel rotates, notches (Fig.
8) pass through the sync signal generator.
When the cam gear is rotating, the sensor will
detect the notches. 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 a notch has passed, the input voltage
switches back low to approximately 0.3 volts.
Fig. 6 CMP OPERATION- 3.7L V-6
1 - NOTCHES
2 - RIGHT CYLINDER HEAD
3 - CMP
4 - TONEWHEEL (TARGET WHEEL)
DRIGNITION CONTROL 8I - 7