change time DODGE NEON 1999 Service Owner's Manual

TIRE NOISE OR VIBRATION
Radial-ply tires are sensitive to force impulses
caused by improper mounting, vibration, wheel
defects, or possibly tire imbalance.
To find out if tires are causing the noise or vibra-
tion, drive the vehicle over a smooth road at varying
speeds. Note the noise level during acceleration and
deceleration. The engine, differential and exhaust
noises will change as speed varies, while the tire
noise will usually remain constant.
LEAD CORRECTION CHART
Use the following chart to diagnose a vehicle that
has a complaint of a drift or lead condition. The use
of the chart will help to determine if the lead condi-
tion is the result of a bad tire or is caused by the
front wheel alignment.
SERVICE PROCEDURES
TIRE AND WHEEL ROTATION
NON-DIRECTIONAL TREAD PATTERN TIRES
Tires on the front and rear axles operate at differ-
ent loads and perform different functions. For these
reasons, they wear at unequal rates, and tend to
develop irregular wear patterns. These effects can be
reduced by timely rotation of tires. The benefits of
rotation are especially worthwhile. Rotation will
increase tread life, help to maintain mud, snow, and
wet traction levels, and contribute to a smooth, quiet
ride.
The suggested rotation method is the forward-cross
tire rotation method (Fig. 6). This method takes
advantage of current tire industry practice whichallows rotation of radial-ply tires. Other rotation
methods may be used, but may not have all the ben-
efits of the recommended method.
NOTE: Only the 4 tire rotation method may be used
if the vehicle is equipped with a low mileage or tem-
porary spare tire.
DIRECTIONAL TREAD PATTERN TIRES
Some vehicles are fitted with special high-perfor-
mance tires having a directional tread pattern. These
tires are designed to improve traction on wet pave-
ment. To obtain the full benefits of this design, the
tires must be installed so that they rotate in the cor-
rect direction. This is indicated by arrows on the tire
sidewalls.
When wheels and tires are being installed, extra
care is needed to ensure that this direction of rota-
tion is maintained.
Refer to Owner's Manual for rotation schedule.
REPAIRING TIRE LEAKS
For proper repairing, a radial tire must be removed
from the wheel. Repairs should only be made if the
defect, or puncture, is in the tread area (Fig. 7). The
tire should be replaced if the puncture is located in
the sidewall.
Deflate tire completely before attempting to dis-
mount the tire from the wheel.Use a lubricant
such as a mild soap solution when dismounting
or mounting tire.Use tools free of burrs or sharp
edges which could damage the tire or wheel rim.
Before mounting tire on wheel, make sure all rust
is removed from the rim bead and repaint if neces-
sary.
Fig. 5 Tire Wear Patterns
22 - 4 TIRES AND WHEELSPL
DIAGNOSIS AND TESTING (Continued)

cranking. Whenever the Powertrain Control Module
(PCM) sets a Diagnostic Trouble Code (DTC) that
affects vehicle emissions, it illuminates the MIL. If a
problem is detected, the PCM sends a message over
the CCD Bus to the instrument cluster to illuminate
the lamp. The PCM illuminates the MIL only for
DTC's that affect vehicle emissions. The MIL stays
on continuously when the PCM has entered a
Limp-In mode or identified a failed emission compo-
nent or system. The MIL remains on until the DTC
is erased. Refer to the Diagnostic Trouble Code
charts in this group for emission related codes.
Also, the MIL either flashes or illuminates contin-
uously when the PCM detects active engine misfire.
Refer to Misfire Monitoring in this section.
Additionally, the PCM may reset (turn off) the MIL
when one of the following occur:
²PCM does not detect the malfunction for 3 con-
secutive trips (except misfire and fuel system moni-
tors).
²PCM does not detect a malfunction while per-
forming three successive engine misfire or fuel sys-
tem tests. The PCM performs these tests while the
engine is operating within6375 RPM of and within
10 % of the load of the operating condition at which
the malfunction was first detected.
STATE DISPLAY TEST MODE
The switch inputs to the Powertrain Control Mod-
ule (PCM) have two recognized states; HIGH and
LOW. For this reason, the PCM cannot recognize the
difference between a selected switch position versus
an open circuit, a short circuit, or a defective switch.
If the State Display screen shows the change from
HIGH to LOW or LOW to HIGH, assume the entire
switch circuit to the PCM functions properly. From
the state display screen, access either State Display
Inputs and Outputs or State Display Sensors.
CIRCUIT ACTUATION TEST MODE
The Circuit Actuation Test Mode checks for proper
operation of output circuits or devices the Powertrain
Control Module (PCM) may not internally recognize.
The PCM attempts to activate these outputs and
allow an observer to verify proper operation. Most of
the tests provide an audible or visual indication of
device operation (click of relay contacts, fuel spray,
etc.). Except for intermittent conditions, if a device
functions properly during testing, assume the device,
its associated wiring, and driver circuit work cor-
rectly.
DIAGNOSTIC TROUBLE CODES
A Diagnostic Trouble Code (DTC) indicates the
PCM has recognized an abnormal condition in the
system.
²The preferred and most accurate method of
retrieving a DTC is by using the DRB scan tool. The
scan tool supplies detailed diagnostic information
which can be used to more accurately diagnose
causes for a DTC.
Remember that DTC's are the results of a sys-
tem or circuit failure, but do not directly iden-
tify the failed component or components.
NOTE: For a list of DTC's, refer to the charts in this
section.
BULB CHECK
Each time the ignition key is turned to the ON
position, the malfunction indicator (check engine)
lamp on the instrument panel should illuminate for
approximately 2 seconds then go out. This is done for
a bulb check.
OBTAINING DTC'S USING DRB SCAN TOOL
(1) Connect the DRB scan tool to the data link
(diagnostic) connector. This connector is located in
the passenger compartment; at the lower edge of
instrument panel; near the steering column.
(2) Turn the ignition switch on and access the
ªRead Faultº screen.
(3) Record all the DTC's and ªfreeze frameº infor-
mation shown on the DRB scan tool.
(4) To erase DTC's, use the ªErase Trouble Codeº
data screen on the DRB scan tool.Do not erase any
DTC's until problems have been investigated
and repairs have been performed.
* Check Engine Lamp (MIL) will not illuminate if
this Diagnostic Trouble Code was recorded. Cycle
Ignition key as described in manual and observe code
flashed by Check Engine lamp.
Fig. 1 Data Link (Diagnostic) Connector
25 - 2 EMISSION CONTROL SYSTEMSPL
DESCRIPTION AND OPERATION (Continued)

HEX
CODEGENERIC
SCAN
TOOL
CODEDRB SCAN TOOL
DISPLAYDESCRIPTION OF DIAGNOSTIC TROUBLE CODE
20 P0134 Right Rear (or just)
Upstream O2S Stays at
CenterNeither rich or lean condition detected from the oxygen
sensor.
21* P1281 Engine Is Cold Too Long Engine did not reach operating temperature within
acceptable limits.
23 P0500 No Vehicle Speed Sensor
SignalNo vehicle speed sensor signal detected during road
load conditions.
24 P0107 MAP Sensor Voltage Too
LowMAP sensor input below minimum acceptable voltage.
25 P0108 MAP Sensor Voltage Too
HighMAP sensor input above maximum acceptable voltage.
27 P1297 No Change in MAP From
Start to RunNo difference recognized between the engine MAP
reading and the barometric (atmospheric) pressure
reading from start-up.
28* P0320 No Crank Reference
Signal at PCMNo crank reference signal detected during engine
cranking.
2A P0352 Ignition Coil #2 Primary
CircuitPeak primary circuit current not achieved with maximum
dwell time.
2B P0351 Ignition Coil #1 Primary
CircuitPeak primary circuit current not achieved with maximum
dwell time.
2C* P1389 No ASD Relay Output
Voltage at PCMAn Open condition Detected In The ASD Relay Output
Circuit.
2E P0401 EGR System Failure Required change in air/fuel ratio not detected during
diagnostic test.
30* P1697 PCM Failure SRI Miles
Not StoredUnsuccessful attempt to update EMR mileage in the
PCM EEPROM
31 P1696 PCM Failure EEPROM
Write DeniedUnsuccessful attempt to write to an EEPROM location
by the PCM.
39 P0112 Intake Air Temp Sensor
Voltage LowIntake air temperature sensor input below the maximum
acceptable voltage.
3A P0113 Intake Air Temp Sensor
Voltage HighIntake air temperature sensor input above the minimum
acceptable voltage.
3C P0106 Barometric Pressure Out
of RangeMAP sensor has a baro reading below an acceptablr
level.
3D P0204 Injector #4 Control Circuit Injector #4 output driver does not respond properly to
the control signal.
3E P0132 Right Rear (or just)
Upstream O2S Shorted to
VoltageOxygen sensor input voltage maintained above the
normal operating range.
44 P0600 PCM Failure SPI
CommunicationsPCM Internal fault condition detected.
52 P1683 S/C Power Relay Ckt An open or shorted condition detected in the speed
control servo power control circuit
65* P1282 Fuel Pump Relay Control
CircuitAn open or shorted condition detected in the fuel pump
relay control circuit.
25 - 4 EMISSION CONTROL SYSTEMSPL
DESCRIPTION AND OPERATION (Continued)

Following is a description of each system monitor,
and its DTC.
Refer to the appropriate Powertrain Diagnos-
tics Procedures manual for diagnostic proce-
dures.
HEX 66, and 7AÐOXYGEN SENSOR (O2S)
MONITOR
Effective control of exhaust emissions is achieved
by an oxygen feedback system. The most important
element of the feedback system is the O2S. The O2S
is located in the exhaust path. Once it reaches oper-
ating temperature 300É to 350ÉC (572É to 662ÉF), the
sensor generates a voltage that is inversely propor-
tional to the amount of oxygen in the exhaust. The
information obtained by the sensor is used to calcu-
late the fuel injector pulse width. This maintains a
14.7 to 1 air fuel (A/F) ratio. At this mixture ratio,
the catalyst works best to remove hydrocarbons (HC),
carbon monoxide (CO) and nitrous oxide (NOx) from
the exhaust.
The O2S is also the main sensing element for the
EGR, Catalyst and Fuel Monitors.
The O2S may fail in any or all of the following
manners:
²Slow response rate
²Reduced output voltage
²Dynamic shift
²Shorted or open circuits
Response rate is the time required for the sensor to
switch from lean to rich once it is exposed to a richer
than optimum A/F mixture or vice versa. As the sen-
sor starts malfunctioning, it could take longer to
detect the changes in the oxygen content of the
exhaust gas.
The output voltage of the O2S ranges from 0 to 1
volt. A good sensor can easily generate any output
voltage in this range as it is exposed to different con-
centrations of oxygen. To detect a shift in the A/F
mixture (lean or rich), the output voltage has to
change beyond a threshold value. A malfunctioning
sensor could have difficulty changing beyond the
threshold value.
HEX 67, 69, 7C, and 7DÐOXYGEN SENSOR
HEATER MONITOR
If there is an oxygen sensor (O2S) DTC as well as
a O2S heater DTC, the O2S fault MUST be repaired
first. After the O2S fault is repaired, verify that the
heater circuit is operating correctly.
Effective control of exhaust emissions is achieved
by an oxygen feedback system. The most important
element of the feedback system is the O2S. The O2S
is located in the exhaust path. Once it reaches oper-
ating temperature 300É to 350ÉC (572 Éto 662ÉF), the
sensor generates a voltage that is inversely propor-
tional to the amount of oxygen in the exhaust. Theinformation obtained by the sensor is used to calcu-
late the fuel injector pulse width. This maintains a
14.7 to 1 Air Fuel (A/F) ratio. At this mixture ratio,
the catalyst works best to remove hydrocarbons (HC),
carbon monoxide (CO) and nitrogen oxide (NOx) from
the exhaust.
The voltage readings taken from the O2S are very
temperature sensitive. The readings are not accurate
below 300ÉC. Heating of the O2S is done to allow the
engine controller to shift to closed loop control as
soon as possible. The heating element used to heat
the O2S must be tested to ensure that it is heating
the sensor properly.
The O2S circuit is monitored for a drop in voltage.
The sensor output is used to test the heater by iso-
lating the effect of the heater element on the O2S
output voltage from the other effects.
HEX 2EÐEGR MONITOR
The Powertrain Control Module (PCM) performs
an on-board diagnostic check of the EGR system.
The EGR system consists of two main components:
a vacuum solenoid back pressure transducer and a
vacuum operated valve. The EGR monitor is used to
test whether the EGR system is operating within
specifications. The diagnostic check activates only
during selected engine/driving conditions. When the
conditions are met, the EGR is turned off (solenoid
energized) and the O2S compensation control is mon-
itored. Turning off the EGR shifts the air fuel (A/F)
ratio in the lean direction. The O2S data should indi-
cate an increase in the O2 concentration in the com-
bustion chamber when the exhaust gases are no
longer recirculated. While this test does not directly
measure the operation of the EGR system, it can be
inferred from the shift in the O2S data whether the
EGR system is operating correctly. Because the O2S
is being used, the O2S test must pass its test before
the EGR test.
HEX 6A,6B, 6C, 6D, 6E, AE, and AFÐMISFIRE
MONITOR
Excessive engine misfire results in increased cata-
lyst temperature and causes an increase in HC emis-
sions. Severe misfires could cause catalyst damage.
To prevent catalytic convertor damage, the PCM
monitors engine misfire.
The Powertrain Control Module (PCM) monitors
for misfire during most engine operating conditions
(positive torque) by looking at changes in the crank-
shaft speed. If a misfire occurs the speed of the
crankshaft will vary more than normal.
HEX 76, 77, 78, and 79ÐFUEL SYSTEM
MONITOR
To comply with clean air regulations, vehicles are
equipped with catalytic converters. These converters
PLEMISSION CONTROL SYSTEMS 25 - 7
DESCRIPTION AND OPERATION (Continued)