speed DODGE NEON 1999 Service Owner's Guide

DESCRIPTION AND OPERATION
HYDRAULIC CLUTCH SYSTEM Ð RIGHT HAND
DRIVE (RHD)
The hydraulic clutch linkage consists of a clutch
master cylinder, remote hydraulic fluid reservoir,
lower clutch slave cylinder, damper, and hydraulic
lines. The clutch master cylinder is connected to the
clutch pedal. The slave cylinder push rod is con-
nected to the clutch release fork. The clutch master
cylinder is mounted on the driver's side of the dash
panel adjacent to the brake master cylinder and
booster assembly.
NOTE: The clutch hydraulic system is serviced as
two separate systems (master cylinder assembly
w/lines and lower slave cylinder assembly w/lines. If
a malfunction occurs within a system, replacement
of that system is required. It is not recommended or
necessary to bleed the clutch hydraulic system. The
service parts are prefilled.
CLUTCH PEDAL POSITION SWITCH Ð RIGHT
HAND DRIVE (RHD)
For description, operation, and diagnosis of the
clutch pedal position switch refer to the Left Hand
Drive (LHD) information for the clutch pedal position
switch.
DIAGNOSIS AND TESTING
CLUTCH DIAGNOSIS Ð RIGHT HAND DRIVE
(RHD)
Problem diagnosis will generally require a road
test to determine the type of fault. Component
inspection will then determine the problem after road
testing.
Drive the vehicle at normal speeds during road
test. Shift the transaxle through all gear ranges and
observe clutch action. If chatter, grab, slip, or
improper release is experienced, remove and inspect
the clutch components. If the problem is noise or
hard shifting, further diagnosis may be needed. The
transaxle or other driveline components may actually
be at fault.
Fig. 2 Clutch Pedal Position Switch and
Components Ð Right Hand Drive (RHD)
6 - 2 CLUTCHPL

SERVICE DIAGNOSISÐCLUTCH SLIPS
CONDITION POSSIBLE CAUSES CORRECTION
DISC FACING WORN OUT Normal wear. Replace w/modular clutch assembly.
Driver frequently rides (slips) clutch,
results in rapid wear and
overheating.Replace w/modular clutch assembly
Insufficient clutch cover diaphragm
spring tensionReplace w/modular clutch assembly
CLUTCH DISC FACING
CONTAMINATED WITH OIL OR
GREASELeak at rear main oil seal or
transaxle input shaft sealReplace leaking seals. Replace
w/modular clutch assembly.
Excessive amount of grease applied
to input shaft splinesApply less grease to input shaft.
Replace w/modular clutch assembly
Road splash, water entering housing Seal housing. Inspect clutch
assembly.
CLUTCH IS RUNNING
PARTIALLY DISENGAGEDRelease bearing sticking or binding,
does not return to normal running
position.Verify that bearing is actually
binding. Then, replace bearing and
transmission front bearing retainer if
sleeve surface is damaged.
Hydraulic clutch mechanism sticking
or binding causing high preloadVerify that clutch slave cylinder and
fork are free to move
CLUTCH DISC FACINGS HAVE
FRACTURED INTO SMALL
PIECESDriver performs a 5-1 downshift at
vehicle speed in excess of 60 miles
per hourAlert driver to problem cause.
Replace w/modular clutch assembly.
Leak at rear main or transaxle input
shaft sealReplace w/modular clutch assembly.
Replace seal.
Excessive heat from slippage Replace w/modular clutch assembly
6 - 4 CLUTCHPL
DIAGNOSIS AND TESTING (Continued)

WATER PUMP DIAGNOSIS
A quick flow test to tell whether or not the pump is
working is to see if the heater warms properly. A
defective pump will not be able to circulate heated
coolant through the long heater hose.
Another flow test to help determine pump opera-
tion.
WARNING: DO NOT remove radiator cap if the cool-
ing system is hot or under pressure.
(1) Remove radiator cap.
(2) Remove a small amount of coolant from the
system, start the engine and warm up until thermo-
stat opens. With the thermostat open and coolant
level low you will see if the water pump is pumping
coolant through the system.
COOLING SYSTEM FLOW CHECK
To determine whether coolant is flowing through
the cooling system, use the following procedures:
(1) If engine is cold, idle engine until normal oper-
ating temperature is reached. Then feel the upper
radiator hose. If it is hot, coolant is circulating.
WARNING: DO NOT REMOVE THE COOLING SYS-
TEM PRESSURE CAP WITH THE SYSTEM HOT AND
UNDER PRESSURE BECAUSE SERIOUS BURNS
FROM COOLANT CAN OCCUR.
(2) Remove pressure cap when engine is cold,
remove small amount of coolant Idle engine until
thermostat opens, you should observe coolant flow
while looking down the filler neck. Once flow is
detected install the pressure cap.
RADIATOR FAN CONTROL
Fan control is accomplished two ways. The fan
always runs when the air conditioning compressor
clutch is engaged. In addition to this control, the fan
is turned on by the temperature of the coolant which
is sensed by the coolant temperature sensor which
sends the message to the Powertrain Control Module
(PCM). The (PCM) turns on the fan through the
Solid State Fan Relay. The Solid State Fan Relay is
located on the left front inner frame just behind the
radiator. See Wiring Diagrams Manual for circuity
and diagnostics provided.
Switching through the (PCM) provides fan control
for the following conditions.
²The fan will not run during cranking until the
engine starts no matter what the coolant tempera-
ture is.
²Fan will run when the air conditioning clutch is
engaged and low pressure cutout switch is closed.
²Fan will run at vehicle speeds above about 40
mph only if coolant temperature reaches 110ÉC(230ÉF). It will turn off when the temperature drops
to 104ÉC (220ÉF). At speeds below 40 mph the fan
switches on at 102ÉC (215ÉF) and off at 93ÉC (200ÉF).
Refer to Radiator Fan Control Module Group 14,
Fuel Injection for more information.
ELECTRIC FAN MOTOR TEST
Refer to Powertrain Diagnostic Manual for procedure.
TESTING COOLING SYSTEM FOR LEAKS
The system should be full. With the engine not
running, wipe the filler neck sealing seat clean.
Attach a radiator pressure tester to the filler neck,
as shown in (Fig. 9) and apply 104 kPa (15 psi) pres-
sure. If the pressure drops more than 2 psi in 2 min-
utes, inspect the system for external leaks.
Move all hoses at the radiator and heater while
system is pressurize at 15 psi, since some leaks occur
due to engine rock while driving.
If there are no external leaks after the gauge dial
shows a drop in pressure, detach the tester. Start the
engine, and run the engine to normal operating tem-
perature in order to open the thermostat and allow
the coolant to expand. Reattach the tester. If the nee-
dle on the dial fluctuates it indicates a combustion
leak, usually a head gasket leak.
WARNING: WITH THE PRESSURE TESTER IN
PLACE PRESSURE BUILDS UP QUICKLY. ANY
EXCESSIVE PRESSURE BUILD-UP DUE TO CON-
TINUOUS ENGINE OPERATION MUST BE
RELEASED TO A SAFE PRESSURE POINT. NEVER
PERMIT PRESSURE TO EXCEED 138 kPa (20 psi).
If the needle on the dial does not fluctuate, race
the engine a few times. If an abnormal amount of
coolant or steam is emitted from the tail pipe, it may
indicate a faulty head gasket, cracked engine block,
or cracked cylinder head.
Fig. 9 Pressure Testing Cooling SystemÐTypical
7 - 14 COOLINGPL
DIAGNOSIS AND TESTING (Continued)

(5) Connect automatic transmission hoses, if
equipped. Tighten hose clamps to 4 N´m (35 in. lbs.).
(6) Slide fan module down into clip(s) on lower
radiator flange (Fig. 21). For dual fan application
install the right fan module first and then the left
fan module. Install retaining screws and tighten to
7.5 N´m (65 in. lbs.).
(7) Connect the cooling fan motor electrical connec-
tor(s).
(8) Install upper radiator hose. Align the hose and
position the clamp so they will not interfere with the
engine or the hood.
(9) For vehicles equipped with dual fans: Install
the battery tray and battery.
(10) Connect negative cable to battery.
(11) Fill cooling system with coolant. Refer to
Cooling System Refillingin this section.
(12) Operate engine until it reaches normal oper-
ating temperature. Check cooling system and auto-
matic transmission for correct fluid levels.
RADIATOR DRAINCOCK
REMOVAL
(1) Turn the drain cock stem counterclockwise to
unscrew the stem. When the stem is unscrewed to
the end of the threads, pull the stem (Fig. 23) from
the radiator tank.
INSTALLATION
(1) Push the draincock assembly body into the
tank opening.
(2) Tighten the draincock stem by turning clock-
wise to 2.0-2.7 N´m (18-25 in. lbs.).
RADIATOR FANS AND MOTOR
All models use a single speed electric motor driven
cooling system fans. The fan modules includes a
motor, fan blade, and support shroud. The module is
fastened to the radiator by screws.
REMOVAL FAN MODULE
(1) Disconnect fan motor leads from module.
(2) Remove fan module fasteners from radiator
(Fig. 24).
FAN BLADE
There are no repairs to be made to the fan. If the
fan is warped, cracked, or otherwise damaged, it
Fig. 21 Fan Module Mounting
Fig. 22 A/C Condenser to Radiator Mounting Screws
Fig. 23 Draincock
Fig. 24 Servicing Fan Module
7 - 20 COOLINGPL
REMOVAL AND INSTALLATION (Continued)

must be replaced withonlythe recommended part
for adequate strength, performance and safety.
(1) To remove fan from motor shaft, bench support
the motor and motor shaft, while removing the fan
retaining clip, so that the shaft and motor will not be
damaged by excessive force.Surface burr removal
may be required to remove fan from motor
shaft (Fig. 25).Do not permit the fan blades to
touch the bench.
(2) To install fan on motor shaft, slide the fan over
shaft. Support motor and shaft as above while
installing fan retaining clip.
INSTALLATION FAN MODULE
(1) Install module to radiator. Torque shroud to
radiator fasteners to 7.5 N´m (65 in. lbs.).
(2) Connect fan motor lead.For wiring diagrams
of fan motor systems Refer to 8W Wiring Dia-
grams.
ELECTRIC FAN MOTORÐSERVICE
WARNING: Do not disassemble the fan motor from
the support bracket.
Electric fan motor is serviced as an assembly with
the fan module.
FAN SHROUD
Some fan shrouds are equipped with flapped doors
to prevent the shroud from restricting air flow at
high speeds.
All vehicles have fan shrouds to improve fan air
flow efficiency.
The shroud supports the electric fan motor and
fan. For removal and installation procedures, refer to
radiator removal in this Section.
ENGINE BLOCK HEATER
REMOVAL
(1) Drain coolant from radiator and cylinder block.
Refer to Cooling System Drain, Clean, Flush and
Refill of this section for procedure.
(2) Detach power cord plug from heater.
(3) Loosen screw in center of heater. Remove
heater assembly.
INSTALLATION
(1) Thoroughly clean core hole and heater seat.
(2) Insert heater assembly with element loop posi-
tionedupward.
(3) With heater seated, tighten center screw
securely to assure a positive seal.
(4) Fill cooling system with coolant to the proper
level, vent air, and inspect for leaks. Pressurize sys-
tem with Radiator Pressure Tool before looking for
leaks.
ACCESSORY DRIVE BELTS
AIR CONDITIONING COMPRESSOR AND
POWER STEERING PUMP
(1) Loosen the power steering pump locking bolts
A and B and pivot bolt C (Fig. 26) to remove and
install belt and/or adjust belt tension.
(2) Using a 1/2º breaker bar, adjust belt tension by
applying torque to the square D hole on the power
steering pivot bracket. Adjust tension to specification
given in Belt Tension Chart.
(3) Tighten in order, first tighten locking bolt A to
27 N´m (20 ft. lbs.) then, bolt B to 27 N´m (20 ft. lbs.)
Then pivot bolt C to 54 N´m (40 ft. lbs.).
GENERATOR BELT
(1) Loosen pivot bolt E then locking nut F and
adjusting bolt G (Fig. 27) to remove and install belt
and/or adjust belt tension.
(2) Tighten adjusting bolt G, adjust belt tension to
specification shown in Belt Tension Chart.
(3) Tighten pivot bolt E to 54 N´m (40 ft. lbs.).
Locking nut F to 54 N´m (40 ft. lbs.).
CLEANING AND INSPECTION
WATER PUMP
Replace water pump body assembly if it has any of
these defects:
(1) Cracks or damage on the body.
(2) Coolant leaks from the shaft seal, evident by
coolant traces on the pump body.
(3) Loose or rough turning bearing.
(4) Impeller rubs either the pump body or the
engine block.
Fig. 25 Servicing Radiator Fan
PLCOOLING 7 - 21
REMOVAL AND INSTALLATION (Continued)

NOTE: BLACK OR DARK=0to75%state-of-charge
The battery is INADEQUATELY charged and must
be charged until green dot is visible, (12.4 volts or
greater) before the battery is tested or returned to
use. Refer to Causes of Battery Discharging in this
Group for more information.
NOTE: CLEAR COLOR = Replace Battery
WARNING: DO NOT CHARGE, ASSIST BOOST,
LOAD TEST, OR ADD WATER TO THE BATTERY
WHEN CLEAR COLOR DOT IS VISIBLE. PERSONAL
INJURY MAY OCCUR.
A clear color dot shows electrolyte level in battery
is below the test indicator (Fig. 1). Water cannot be
added to a maintenance free battery. The battery
must be replaced. A low electrolyte level may be
caused by an over charging condition. Refer to Gen-
erator Test Procedures on Vehicle.
CAUSES OF BATTERY DISCHARGING
It is normal to have a small 5 to 25 milliamperes
continuous electrical draw from the battery. This
draw will take place with the ignition in the OFF
position, and the courtesy, dome, storage compart-
ments, and engine compartment lights OFF. The con-
tinuous draw is due to various electronic features or
accessories that require electrical current with the
ignition OFF to function properly. When a vehicle is
not used over an extended period of approximately 20
days the IOD fuse should be pulled. The fuse is
located in the power distribution center. removal of
this fuse will reduce the level of battery discharge.
Refer to the Battery Diagnosis and Testing Table for
proper diagnosis.
ABNORMAL BATTERY DISCHARGING
²Corroded battery posts, cables or terminals.
²Loose or worn generator drive belt.
²Electrical loads that exceed the output of the
charging system due to equipment or accessories
installed after delivery.
²Slow driving speeds in heavy traffic conditions
or prolonged idling with high-amperage electrical
systems in use.
²Defective electrical circuit or component causing
excess Ignition Off Draw (IOD). Refer to Battery
Ignition Off Draw (IOD).
²Defective charging system.
²Defective battery.
BATTERY IGNITION OFF DRAW (IOD)
High current draw on the battery with the ignition
OFF will discharge a battery. After a dead battery is
recharged, the vehicle ignition off draw (IOD) shouldbe checked. To determine if a high current draw con-
dition exists first check the vehicle with a test lamp.
(1) Verify that all electrical accessories are OFF.
²Remove key from ignition switch
²Turn off all lights
²Trunk lid is closed
²Engine compartment hood lamp is disconnected
or lamp removed
²Glove box door is closed
²Sun visor vanity lights are OFF
²All doors are closed
²Allow the ignition key lamp system to time out
in approximately 30 seconds, if equipped.
(2) Disconnect battery negative cable (Fig. 4).
(3) Connect a 12 Volt test lamp, with a cold resis-
tance of 5-7 ohms, between the battery negative cable
clamp and the negative post (Fig. 5). If test lamp
goes out system is OK. If test lamp lights and stays
ON, go to Test Lamp Stays ON procedure.
TEST LAMP STAYS ON
There is either a short circuit or a fault in an elec-
tronic module. Two fuses in the Power Distribution
Center (PDC) feed the modules with ignition off
draw.
²Interior lamps fuse (10 Amp) (IOD) PDC.
²Fuel pump fuse (20 Amp) in PDC
(1) Remove interior lamp and fuel pump fuses. By
removing these fuses all ignition off draw from the
vehicle electronics will be disconnected. The test
lamp should go out. If test lamp goes out go to Step
2. If test lamp does not go out there is a current
draw or short circuit. Refer to Group 8W, Wiring Dia-
grams.
(2) Install the fuel pump fuse. If test lamp lights,
there is a current draw or short circuit in the A14
wiring circuit feed.
(a) Disconnect Powertrain Control Module.
(b) If test lamp goes out, replace Powertrain
Control Module.
(c) If test lamp does not go out, there is a cur-
rent draw or short circuit in the A14 circuit feed.
Refer to Group 8W, Wiring Diagrams.
(3) Install the interior lamp fuse. If test lamp
lights, there is a current draw or short circuit in the
M01 circuit. Refer to Group 8W, Wiring Diagrams. If
test lamp stays out, go to Step 4
(4) Use a multi-meter that has at least a range of
200 milliamperes. Install meter between the battery
negative cable and battery negative post (Fig. 6).
Carefully remove the test lamp without disconnecting
the meter. After all modules time-out the total vehi-
cle IOD should be less than 10 milliamperes. If igni-
tion off draw is more than 10 milliamperes go to Step
5.
(5) Remove both fuses from the Power Distribution
Center:
PLBATTERY 8A - 3
DIAGNOSIS AND TESTING (Continued)

These tests will show the amount of voltage drop
across the generator output wire from the generator
output (B+) terminal to the battery positive post.
They will also show the amount of voltage drop from
the ground (-) terminal on the generator (Fig. 2) to
the battery negative post.
A voltmeter with a 0±18 volt DC scale should be
used for these tests. By repositioning the voltmeter
test leads, the point of high resistance (voltage drop)
can easily be found.
Test points on the generator may be reached by
either removing the air cleaner housing or below by
raising the vehicle on a hoist.
PREPARATION
(1) Before starting test, make sure battery is in
good condition and is fully-charged. See Group 8A,
Battery for more information.
(2) Check condition of battery cables at battery.
Clean if necessary.
(3) Start the engine and allow it to reach normal
operating temperature.
(4) Shut engine off.
(5) Connect an engine tachometer.
(6) Fully engage the parking brake.
TEST
(1) Start engine.
(2) Place heater blower in high position.
(3) Turn on headlamps and place in high-beam
position.
(4) Turn vehicle interior lamps on.
(5) Start engine. Bring engine speed up to 2400
rpm and hold.
(6) Testing (- ground) circuitry:
(a) Touch the negative lead of voltmeter directly
to battery positivePOST(Fig. 4).
(b) Touch the positive lead of voltmeter to the
B+ output terminal stud on the generator (not the
terminal mounting nut). Voltage should be no
higher than 0.6 volts. If voltage is higher than 0.6
volts, touch test lead to terminal mounting stud
nut and then to the wiring connector. If voltage is
now below 0.6 volts, look for dirty, loose or poor
connection at this point. Refer to Group 8, Wiring
for connector location. A voltage drop test may be
Fig. 2 Generator Terminals
Fig. 3 Electrical Resistance Test
Fig. 4 Battery Voltage Test
PLCHARGING SYSTEM 8C - 7
DIAGNOSIS AND TESTING (Continued)

performed at each (- ground) connection in this cir-
cuit to locate the excessive resistance.
(7) Testing (+ positive) circuitry:
(a) Touch the positive lead of voltmeter directly
to battery negativePOST.
(b) Touch the negative lead of voltmeter to the
ground terminal stud on the generator case (not
the terminal mounting nut). Voltage should be no
higher than 0.3 volts. If voltage is higher than 0.3
volts, touch test lead to terminal mounting stud
nut and then to the wiring connector. If voltage is
now below 0.3 volts, look for dirty, loose or poor
connection at this point. A voltage drop test may be
performed at each (+ positive) connection in this
circuit to locate the excessive resistance. This test
can also be performed between the generator case
and the engine. If test voltage is higher than 0.3
volts, check for corrosion at generator mounting
points or loose generator mounting.
CURRENT OUTPUT TEST
The current output test will determine if the
charging system can deliver its minimum test cur-
rent (amperage) output. Refer to the Specifications
section at the end of this group for minimum test
current (amperage) requirements.
The first part of this test will determine the com-
bined amperage output of both the generator and the
Electronic Voltage Regulator (EVR) circuitry.
PREPARATION
(1) Determine if any Diagnostic Trouble Codes
(DTC) exist. To determine a DTC, refer to On-Board
Diagnostics in this group. For repair, refer to the
appropriate Powertrain Diagnostic Procedures man-
ual.
(2) Before starting test, make sure battery is in
good condition and is fully-charged. See Group 8A,
Battery for more information.
(3) Check condition of battery cables at battery.
Clean if necessary.
(4) Perform the Voltage Drop Test. This will
ensure clean and tight generator/battery electrical
connections.
(5) Be sure the generator drive belt is properly
tensioned. Refer to Group 7, Cooling System for
information.
(6) A volt/amp tester equipped with both a battery
load control (carbon pile rheostat) and an inductive-
type pickup clamp (ammeter probe) will be used for
this test. Refer to operating instructions supplied
with tester. When using a tester equipped with an
inductive-type clamp, removal of wiring at the gener-
ator will not be necessary.
(7) Start the engine and allow it to reach operating
temperature.
(8) Shut engine off.(9) Turn off all electrical accessories and all vehicle
lighting.
(10) Connect the volt/amp tester leads to the bat-
tery. Be sure the carbon pile rheostat control is in the
OPEN or OFF position before connecting leads. See
Load Test in Group 8A, Battery for more information.
Also refer to the operating instructions supplied with
test equipment.
(11) Connect the inductive clamp (ammeter probe).
Refer to the operating instructions supplied with test
equipment.
(12) If volt/amp tester is not equipped with an
engine tachometer, connect a separate tachometer to
the engine.
TEST
(1) Perform the previous test Preparation.
(2) Fully engage the parking brake.
(3) Start engine.
(4) Bring engine speed to 2500 rpm.
(5) With engine speed held at 2500 rpm, slowly
adjust the rheostat control (load) on the tester to
obtain the highest amperage reading. Do not allow
voltage to drop below 12 volts. Record the reading.
This load test must be performed within 15 sec-
onds to prevent damage to test equipment.On
certain brands of test equipment, this load will be
applied automatically. Refer to the operating manual
supplied with test equipment.
(6) The ammeter reading must meet the Minimum
Test Amps specifications as displayed in the Genera-
tor Ratings chart. This can be found in the Specifica-
tions section at the end of this group. A label stating
a part reference number is attached to the generator
case. On some engines this label may be located on
the bottom of the case. Compare this reference num-
ber to the Generator Ratings chart.
(7) Rotate the load control to the OFF position.
(8) Continue holding engine speed at 2500. If EVR
circuitry is OK, amperage should drop below 15±20
amps. With all electrical accessories and vehicle
lighting off, this could take several minutes of engine
operation. If amperage did not drop, refer to the
appropriate Powertrain Diagnostic Procedures man-
ual for testing.
(9) Remove volt/amp tester.
If minimum amperage could not be met, refer to
the appropriate Powertrain Diagnostic Procedures
manual for testing.
BATTERY TEMPERATURE SENSOR
To perform a complete test of this sensor and its
circuitry, refer to the appropriate Powertrain Diag-
nostic Procedures manual. To test the sensor only,
refer to the following:
(1) The sensor is located under the battery and is
attached to the battery tray (Fig. 5). A two-wire pig-
8C - 8 CHARGING SYSTEMPL
DIAGNOSIS AND TESTING (Continued)

Plastic clips in various locations protect the cables
from damage. When the cables are replaced the clips
must be used to prevent damage to the cables. The
#1 cable must be routed under the PCV hose and
clipped to the #2 cable.
ELECTRONIC IGNITION COILS
WARNING: THE DIRECT IGNITION SYSTEM GEN-
ERATES APPROXIMATELY 40,000 VOLTS. PER-
SONAL INJURY COULD RESULT FROM CONTACT
WITH THIS SYSTEM.
The coil pack consists of 2 coils molded together.
The coil pack is mounted on the valve cover (Fig. 3)
or (Fig. 4). High tension leads route to each cylinder
from the coil. The coil fires two spark plugs every
power stroke. One plug is the cylinder under com-
pression, the other cylinder fires on the exhaust
stroke. Coil number one fires cylinders 1 and 4. Coil
number two fires cylinders 2 and 3. The PCM deter-
mines which of the coils to charge and fire at the cor-
rect time.
The Auto Shutdown (ASD) relay provides battery
voltage to the ignition coil. The PCM provides a
ground contact (circuit) for energizing the coil. When
the PCM breaks the contact, the energy in the coil
primary transfers to the secondary causing the
spark. The PCM will de-energize the ASD relay if it
does not receive the crankshaft position sensor and
camshaft position sensor inputs. Refer to Auto Shut-
down (ASD) RelayÐPCM Output, in this section for
relay operation.
AUTOMATIC SHUTDOWN RELAY
The Automatic Shutdown (ASD) relay supplies bat-
tery voltage to the fuel injectors, electronic ignition
coil and the heating elements in the oxygen sensors.
A buss bar in the Power Distribution Center (PDC)
supplies voltage to the solenoid side and contact sideof the relay. The ASD relay power circuit contains a
20 amp fuse between the buss bar in the PDC and
the relay. The fuse also protects the power circuit for
the fuel pump relay and pump. The fuse is located in
the PDC. Refer to Group 8W, Wiring Diagrams for
circuit information.
The PCM controls the ASD relay by switching the
ground path for the solenoid side of the relay on and
off. The PCM turns the ground path off when the
ignition switch is in the Off position. When the igni-
tion switch is in On or Start, the PCM monitors the
crankshaft and camshaft position sensor signals to
determine engine speed and ignition timing (coil
dwell). If the PCM does not receive crankshaft and
camshaft position sensor signals when the ignition
switch is in the Run position, it will de-energize the
ASD relay.
The ASD relay is located in the PDC (Fig. 5). The
inside top of the PDC cover has label showing relay
and fuse identification.
Fig. 3 Ignition Coil PackÐSOHC
Fig. 4 Ignition Coil PackÐDOHC
Fig. 5 Power Distribution Center (PDC)
PLIGNITION SYSTEM 8D - 3
DESCRIPTION AND OPERATION (Continued)

CRANKSHAFT POSITION SENSOR
The PCM determines what cylinder to fire from the
crankshaft position sensor input and the camshaft
position sensor input. The second crankshaft counter-
weight has machined into it two sets of four timing
reference notches including a 60 degree signature
notch (Fig. 6). From the crankshaft position sensor
input the PCM determines engine speed and crank-
shaft angle (position).
The notches generate pulses from high to low in
the crankshaft position sensor output voltage. When
a metal portion of the counterweight aligns with the
crankshaft position sensor, the sensor output voltage
goes low (less than 0.5 volts). When a notch aligns
with the sensor, voltage goes high (5.0 volts). As a
group of notches pass under the sensor, the output
voltage switches from low (metal) to high (notch)
then back to low.
If available, an oscilloscope can display the square
wave patterns of each voltage pulse. From the fre-
quency of the output voltage pulses, the PCM calcu-
lates engine speed. The width of the pulses represent
the amount of time the output voltage stays high
before switching back to low. The period of time the
sensor output voltage stays high before switching
back to low is referred to as pulse-width. The faster
the engine is operating, the smaller the pulse-width
on the oscilloscope.
By counting the pulses and referencing the pulse
from the 60 degree signature notch, the PCM calcu-
lates crankshaft angle (position). In each group of
timing reference notches, the first notch represents
69 degrees before top dead center (BTDC). The sec-
ond notch represents 49 degrees BTDC. The third
notch represents 29 degrees. The last notch in eachset represents 9 degrees before top dead center
BTDC.
The timing reference notches are machined at 20É
increments. From the voltage pulse-width the PCM
tells the difference between the timing reference
notches and the 60 degree signature notch. The 60
degree signature notch produces a longer pulse-width
than the smaller timing reference notches. If the
camshaft position sensor input switches from high to
low when the 60 degree signature notch passes under
the crankshaft position sensor, the PCM knows cylin-
der number one is the next cylinder at TDC.
The crankshaft position sensor mounts to the
engine block behind the generator, just above the oil
filter (Fig. 7).
CAMSHAFT POSITION SENSOR
The PCM determines fuel injection synchronization
and cylinder identification from inputs provided by
Fig. 6 Timing Reference Notches
Fig. 7 Crankshaft Position Sensor
8D - 4 IGNITION SYSTEMPL
DESCRIPTION AND OPERATION (Continued)