sensor CHRYSLER VOYAGER 2001 Service Manual

Euro Stage III OBD MONITOR INFORMATION
Comprehensive Major Monitors Major Monitors
Components Non Fuel Control Fuel Control
Monitor & Non Misfire & Misfire
Run constantly Run Once Per Trip Run Constantly
Includes All Engine Hardware Monitors Entire Emission Monitors Entire System
- Sensors, Switches, System
Solenoids, etc.
One Trip Faults - Turns On Two Trip Faults - Turns On Two Trip Faults - Turns On
The MIL and Sets DTC After The MIL and Sets DTC After The MIL and Sets DTC After
One Failure Two Consecutive Failures Two Consecutive Failures
Priority 3 Priority 1 or 3 Priority 2 or 4
All Checked For Continuity Done Stop Testing = Yes
Fuel Control Monitor
Open Monitors Fuel Control
Short To Ground Oxygen Sensor Heater System For:
Short To Voltage Oxygen Sensor Response
Fuel System Lean
Fuel System Rich
Inputs Checked For
Requires 3 Consecutive Rationality
Catalytic Converter
Fuel System Good TripsTo Efficiency Except EWMA
Extinguish The MIL Outputs Checked For - up to 6 tests per trip
Functionality and a one trip fault
EGR System
Misfire Monitor
Evaporative Emission Monitors For Engine Misfire
System at:
(Purge and Leak) 1000 RPM Counter
Non-LDP (Type B)
or **200 RPM Counter
LDP (Type A)
Requires 3 Consecutive Requires 3 Consecutive Requires 3 Consecutive
Global/Alternate Good Trips Global Good Trips Misfire Good Trips
to Extinguish the MIL* to Extinguish the MIL* To Extinguish the MIL
*40 Warm Up Cyclesare required to erase **Type A misfire is a two
DTC's
afterthe MIL has been extinguished. trip failure. The MIL will
illuminate and blink at
the first failure.
3
GENERAL INFORMATION

3.2.3 OTHER CONTROLS
CHARGING SYSTEM
The charging system is turned on when the
engine is started and ASD relay energized. When
the ASD relay is on, ASD output voltage is supplied
to the ASD sense circuit at the PCM. This voltage is
connected in some cases, through the PCM and
supplied to one of the generator field terminals
(Gen Source +). All others, the Gen field is con-
nected directly to the ASD output voltage. The
amount of current produced by the generator is
controlled by the Electronic Voltage Regulator
(EVR) circuitry, in the PCM. Battery temperature is
determined from IAT. This temperature along with
sensed line voltage, is used by the PCM to vary the
battery charging rate. This is done by cycling the
ground path to the other generator field terminal
(Gen field driver).
SPEED CONTROL SYSTEM
The PCM controls vehicle speed by operation of
the speed control servo vacuum and vent solenoids.
Energizing the vacuum solenoid applies vacuum to
the servo to increase throttle position. Operation of
the vent solenoid slowly releases the vacuum allow-
ing throttle position to decrease. A special dump
solenoid allows immediate release of throttle posi-
tion caused by braking, cruise control switch turned
off, shifting into neutral, excessive RPM (tires spin-
ning) or ignition off.
LEAK DETECTION PUMP SYSTEM (IF EQUIPPED)
The leak detection pump is a device that pressur-
izes the evaporative system to determine if there
are any leaks. When certain conditions are met, the
PCM will activate the pump and start counting
pump strokes. If the pump stops within a calibrated
number of strokes, the system is determined to be
normal. If the pump does not stop or stops too soon,
a DTC will be set.
3.2.4 PCM OPERATING MODES
As input signals to the PCM change, the PCM
adjusts its response to output devices. For example,
the PCM must calculate a different injector pulse
width and ignition timing for idle than it does for
wide open throttle. There are several different
modes of operation that determine how the PCM
responds to the various input signals.
There are two types of engine control operation:
open loopandclosed loop.
Inopen loopoperation, the PCM receives input
signals and responds according to preset program-
ming. Inputs from the heated oxygen sensors are
not monitored.Inclosed loopoperation, the PCM monitors the
inputs from the heated oxygen sensors. This input
indicates to the PCM whether or not the calculated
injector pulse width results in the ideal air-fuel
ratio of 14.7 parts air to 1 part fuel. By monitoring
the exhaust oxygen content through the oxygen
sensor, the PCM can fine tune injector pulse width.
Fine tuning injector pulse width allows the PCM to
achieve the lowest emission levels while maintain-
ing optimum fuel economy.
The engine start-up (crank), engine warm-up,
and wide open throttle modes are open loop modes.
Under most operating conditions, closed loop modes
occur with the engine at operating temperature.
IGNITION SWITCH ON (ENGINE OFF) MODE
When the ignition switch activates the fuel injec-
tion system, the following actions occur:
1. The PCM determines atmospheric air pressure
from the MAP sensor input to determine basic
fuel strategy.
2. The PCM monitors the engine coolant tempera-
ture sensor and throttle position sensor input.
The PCM modifies fuel strategy based on this
input.
When the key is in the on position and the engine
is not running (zero rpm), the auto shutdown relay
and fuel pump relay are not energized. Therefore,
voltage is not supplied to the fuel pump, ignition
coil, and fuel injectors.
Engine Start-up ModeÐ This is an open loop
mode. The following actions occur when the starter
motor is engaged:
1. The auto shutdown and fuel pump relays are
energized. If the PCM does not receive the cam-
shaft and crankshaft signal within approxi-
mately one second, these relays are de-
energized.
2. The PCM energizes all fuel injectors until it
determines crankshaft position from the cam-
shaft and crankshaft signals. The PCM deter-
mines crankshaft position within one engine
revolution. After the camshaft position has been
determined, the PCM energizes the fuel injectors
in sequence. The PCM adjusts the injector pulse
width and synchronizes the fuel injectors by
controlling the fuel injectors' ground paths.
3. Once the engine idles within 64 rpm of its target
engine speed, the PCM compares the current
MAP sensor value with the value received dur-
ing the ignition switch on (zero rpm) mode. A
diagnostic trouble code is written to PCM mem-
ory if a minimum difference between the two
values is not found.
4
GENERAL INFORMATION

Once the auto shutdown and fuel pump relays
have been energized, the PCM determines the fuel
injector pulse width based on the following:
± engine coolant temperature
± manifold absolute pressure
± intake air temperature
± engine revolutions
± throttle position
The PCM determines the spark advance based on
the following:
± engine coolant temperature
± crankshaft position
± intake air temperature
± manifold absolute pressure
± throttle position
Engine Warm-Up Modeþ This is an open loop
mode. The PCM adjusts injector pulse width and
controls injector synchronization by controlling the
fuel injectors' ground paths. The PCM adjusts igni-
tion timing and engine idle speed. The PCM adjusts
the idle speed by controlling the idle air control
motor.
Cruise or Idle Modeþ When the engine is at
normal operating temperature, this is a closed loop
mode.
Acceleration Modeþ This is a closed loop mode.
The PCM recognizes an increase in throttle position
and a decrease in Manifold Vacuum as engine load
increases. In response, the PCM increases the in-
jector pulse width to meet the increased load. The
A/C compressor may be de-energized for a short
period of time.
Decelerationþ This is a closed loop mode. The
PCM recognizes a decrease in throttle position and
an increase in Manifold Vacuum as engine load
decreases. In response, the PCM decreases the
injector pulse width to meet the decreased load.
Full injector shut off may be obtained during high
speed deceleration.
Wide Open Throttle Modeþ This is an open
loop mode. The throttle position sensor notifies the
PCM of a wide open throttle condition. Once a wide
open throttle is sensed, the PCM de-energizes the
A/C compressor clutch relay for 20 seconds.
3.2.5 NON-MONITORED CIRCUITS
The PCM does not monitor the following circuits,
systems, and conditions even though they could
have malfunctions that result in driveability prob-
lems. A diagnostic code may not be displayed for the
following conditions. However, problems with these
systems may cause a diagnostic code to be displayed
for other systems. For example, a fuel pressure
problem will not register a diagnostic code directly,
but could cause a rich or lean condition. This couldcause an oxygen sensor, fuel system, or misfire
monitor trouble code to be stored in the PCM.
Engine Timingþ The PCM cannot detect an
incorrectly indexed timing chain, camshaft
sprocket, or crankshaft sprocket. The PCM also
cannot detect an incorrectly indexed distributor.(*)
Fuel Pressureþ Fuel pressure is controlled by
the fuel pressure regulator. The PCM cannot detect
a clogged fuel pump inlet filter, clogged in-line filter,
or a pinched fuel supply.(*)
Fuel Injectorsþ The PCM cannot detect if a fuel
injector is clogged, the pintle is sticking, or the
wrong injectors are installed.(*)
Fuel Requirementsþ Poor quality gasoline can
cause problems such as hard starting, stalling, and
stumble. Use of methanol-gasoline blends may re-
sult in starting and driveability problems. See indi-
vidual symptoms and their definitions in Section
6.0 (Glossary of Terms).
PCM Groundsþ The PCM cannot detect a poor
system ground. However, a diagnostic trouble code
may be stored in the PCM as a result of this
condition.
Throttle Body Air Flowþ The PCM cannot
detect a clogged or restricted air cleaner inlet or
filter element.(*)
Exhaust Systemþ The PCM cannot detect a
plugged, restricted, or leaking exhaust system.(*)
Cylinder Compressionþ The PCM cannot de-
tect uneven, low, or high engine cylinder compres-
sion.(*)
Excessive Oil Consumptionþ Although the
PCM monitors the exhaust stream oxygen content
through the oxygen sensor when the system is in a
closed loop, it cannot determine excessive oil con-
sumption.
NOTE: ANY OF THESE CONDITIONS
COULD RESULT IN A RICH OR LEAN
CONDITION CAUSING AN OXYGEN SENSOR
TROUBLE CODE TO BE STORED IN THE
PCM, OR THE VEHICLE MAY EXHIBIT ONE
OR MORE OF THE DRIVEABILITY
SYMPTOMS LISTED IN THE TABLE OF
CONTENTS.
3.2.6 SKIS OVERVIEW
The Sentry Key Immobilizer System (SKIS) is
designed to prevent unauthorized vehicle opera-
tion. The system consists of a Sentry Key Immobi-
lizer Module (SKIM), ignition key(s) equipped with
a transponder chip and PCM. When the ignition
switch is turned on, the SKIM interrogates the
ignition key. If the ignition key is Valid or Invalid,
the SKIM sends a PCI Bus message to the PCM
indicating ignition key status. Upon receiving this
5
GENERAL INFORMATION

message the PCM will terminate engine operation,
or allow the engine to continue to operate.
3.2.7 SKIM ON-BOARD DIAGNOSTICS
The SKIM has been programmed to transmit and
monitor many different coded messages as well as
PCI Bus messages. This monitoring is called On
Board Diagnosis.
Certain criteria must be met for a diagnostic
trouble code to be entered into the SKIM memory.
The criteria may be a range of; Input voltage, PCI
Bus message, or coded messages to the SKIM. If all
of the criteria for monitoring a circuit or function
are met and a fault is sensed, a diagnostic trouble
code will be stored in the SKIM memory.
3.2.8 SKIS OPERATION
When ignition power is supplied to the SKIM, the
SKIM performs an internal self-test. After the self-
test is completed, the SKIM energizes the antenna
(this activates the transponder chip) and sends a
challenge to the transponder chip. The transponder
chip responds to the challenge by generating an
encrypted response message using the following:
Secret Key -This is an electronically stored
value (identification number) that is unique to each
SKIS. The secret key is stored in the SKIM, PCM
and all ignition key transponders.
Challenge- This is a random number that is
generated by the SKIM at each ignition key cycle.
The secret key and challenge are the two vari-
ables used in the algorithm that produces the
encrypted response message. The transponder uses
the crypto algorithm to receive, decode and respond
to the message sent by the SKIM. After responding
to the coded message, the transponder sends a
transponder I.D. message to the SKIM. The SKIM
compares the transponder I.D. to the available valid
key codes in the SKIM memory (8 key maximum at
any one time). After validating the key ignition the
SKIM sends a PCI Bus message called a Seed
Request to the engine controller then waits for a
PCM response. If the PCM does not respond, the
SKIM will send the seed request again. After three
failed attempts the SKIM will stop sending the seed
request and store a trouble code. If the PCM sends
a seed response, the SKIM sends a valid/invalid key
message to the PCM. This is an encrypted message
that is generated using the following:
VIN -Vehicle Identification Number
Seed -This is a random number that is generated
by the PCM at each ignition key cycle.
The VIN and seed are the two variables used in
the rolling code algorithm that encrypts the valid/
invalid key message. The PCM uses the rolling code
algorithm to receive, decode and respond to the
valid/invalid key message sent by the SKIM. Aftersending the valid/invalid key message the SKIM
waits 3.5 seconds for a PCM status message from
the PCM. If the PCM does not respond with a valid
key message to the SKIM, a fault is detected and a
trouble code is stored.
The SKIS incorporates a VTSS LED located on
the instrument panel upper cover. The LED re-
ceives switched ignition voltage and is hardwired to
the body control module. The LED is actuated when
the SKIM sends a PCI Bus message to the body
controller requesting the LED on. The body control-
ler then provides the ground for the LED. The
SKIM will request VTSS LED operation for the
following:
± bulb checks at ignition on
± to alert the vehicle operator to a SKIS mal-
function
± customer key programming mode
For all faults except transponder faults and VTSS
LED remains on steady. In the event of a transpon-
der fault the LED flashes at a rate of 1 Hz (once per
second). If a fault is present the LED will remain on
or flashing for the complete ignition cycle. If a fault
is stored in SKIM memory which prevents the
system from operating properly, the PCM will allow
the engine to start and run (for 2 seconds) up to six
times. After the sixth attempt, the PCM disables
the starter relay until the fault is corrected.
3.2.9 PROGRAMMING THE POWERTRAIN
CONTROL MODULE
Important Note:Before replacing the PCM for a
failed driver, control circuit or ground circuit, be
sure to check the related component/circuit integ-
rity for failures not detected due to a double fault in
the circuit. Most PCM driver/control circuit failures
are caused by internal failure to components (i.e.
12-volt pull-ups, drivers and ground sensors). These
failures are difficult to detect when a double fault
has occurred and only one DTC has set.
NOTE: IF THE PCM AND THE SKIM ARE
REPLACED AT THE SAME TIME, PROGRAM
THE VIN INTO THE PCM FIRST. ALL VEHICLE
KEYS WILL THEN NEED TO BE REPLACED
AND PROGRAMMED TO THE NEW SKIM.
The SKIS Secret Key is an I.D. code that is
unique to each SKIS. This code is programmed and
stored in the SKIM, engine controller and transpon-
der chip (ignition key). When replacing the PCM it
is necessary to program the secret key into the
PCM.
1. Turn the ignition on (transmission in park/
neutral).
2. Use the DRB and select THEFT ALARM, SKIM
then MISCELLANEOUS.
6
GENERAL INFORMATION

powertrain control module checks that circuit or
function. Procedures in this manual verify if the
DTC is a hard code at the beginning of each test.
When it is not a hard code, an intermittent test
must be performed.
DTC's that are for Euro Stage III OBD monitors
will not set with just the ignition key on. Comparing
these to non-emission DTC's, they will seem like an
intermittent. These DTC's require a set of parame-
ters to be performed (The DRBIIItpre-test screens
will help with this for MONITOR DTC's), this is
called a TRIP. All Euro Stage III OBD DTCs will be
set after one or in some cases two trip failures, and
the MIL will be turned on. These DTC's require
three successful, no failures, TRIPS to extinguish
the MIL, followed by 40 warm-up cycles to erase the
DTC.
3.3.2 INTERMITTENT CODE
A diagnostic trouble code that is not there every
time the PCM checks the circuit is an intermittent
DTC. Most intermittent DTC's are caused by wiring
or connector problems. Defects that come and go
like this are the most difficult to diagnose; they
must be looked for under specific conditions that
cause them. The following checks may assist you in
identifying a possible intermittent problem:
²Visually inspect related wire harness connectors.
Look for broken, bent, pushed out, or corroded
terminals.
²Visually inspect the related harnesses. Look for
chafed, pierced, or partially broken wire.
²Refer to any technical service bulletins that may
apply.
²Use the DRBIIItdata recorder or co-pilot.
3.3.3 DISTANCE SINCE MI SET
The Euro Stage III OBD directive requires that
the distance traveled by the vehicle while theMIis
activated must be available at any instant through
the serial port on the standard data link connector.
This feature works as follows:1. If the MI is illuminated due to a fault, the
distance count is updated (i.e. it is counting).
2. If there is a9stale9MI fault (i.e. the fault is still
frozen in memory but the MI has heen extin-
guished due to 3 good trips), the distance count is
held (i.e. frozen).
3. If the distance count is being held due to (Item
2.) and the fault is cleared, the distance is
cleared (set to zero).
4. If the distance count is being held due to (Item
2.) and another MI occurs, the distance count is
reset (to 0) and begins updating anew.
5. If a fault occurs while the MI is already illumi-
nated due to a previous fault (the distance count
is updating), then the distance count continues
to update w/out interruption.
6. If the MI is flashing due to activate misfire and
there is and9active9fault (i.e. matured fault for
which 3 good trips have not occurred), the dis-
tance count behaves as the MI in ON.
7. If the MI is flashing due to active misfire and
there is no9active9fault (i.e. the MI is flashing
for a 1 malf.), the distance count behaves as if
the MI is off (because it is not yet a matured
fault).
8. The distance count is cleared whenever the fault
is cleared. (Via 40 warm up cycles, or via scan
tool).
3.3.4 HANDLING NO DTC PROBLEMS
Symptom checks cannot be used properly unless
the driveability problem characteristic actually
happens while the vehicle is being tested.
Select the symptom that most accurately de-
scribes the vehicle's driveability problem and then
perform the test routine that pertains to this symp-
tom. Perform each routine test in sequence until the
problem is found. For definitions, see Section 6.0
Glossary Of Terms.
SYMPTOM DIAGNOSTIC TEST
HARD START CHECKING THE FUEL PRESSURE
CHECKING THE ECT SENSOR
CHECKING THROTTLE POSITION SENSOR
CHECKING MAP SENSOR
CHECKING IDLE AIR CONTROL MOTOR OPERATION
CHECKING EGR SYSTEM
CHECKING IAT SENSOR
8
GENERAL INFORMATION

SYMPTOM DIAGNOSTIC TEST
START AND STALL CHECKING PCM POWER AND GND CKT
CHECKING THE FUEL PRESSURE
CHECKING ECT SENSOR
CHECKING THROTTLE POSITION SENSOR
CHECKING MAP SENSOR
CHECKING IDLE AIR CONTROL MOTOR OPERATION
HESITATION/SAG/STUMBLE CHECKING PCM POWER AND GND CKT
CHECKING THE FUEL PRESSURE
CHECKING ECT SENSOR
CHECKING THROTTLE POSITION SENSOR
CHECKING MAP SENSOR
SURGE CHECKING IDLE AIR CONTROL MOTOR OPERATION
CHECKING IAT SENSOR
CHECKING PCM POWER AND GND CKT
CHECKING THE FUEL PRESSURE
CHECKING ECT SENSOR
CHECKING THROTTLE POSITION SENSOR
CHECKING MAP SENSOR
CHECKING IDLE AIR CONTROL MOTOR OPERATION
LACK OF POWER/SLUGGISH CHECKING PCM POWER AND GND CKT
CHECKING THE FUEL PRESSURE
CHECKING ECT SENSOR
CHECKING THROTTLE POSTION SENSOR
CHECKING MAP SENSOR
CHECKING IDLE AIR CONTROL MOTOR OPERATION
SPARK KNOCK DETONATION CHECKING PCM POWER AND GND CKT
CHECKING THE FUEL PRESSURE
CHECKING ECT SENSOR
CHECKING THROTTLE POSITION SENSOR
CHECKING MAP SENSOR
CHECKING IDLE AIR CONTROL MOTOR OPERATION
CUTS OUT/MISSES CHECKING PCM POWER AND GND CKT
CHECKING THE FUEL PRESSURE
CHECKING IDLE AIR CONTROL MOTOR OPERATION
BACKFIRE/POPBACK CHECKING PCM POWER AND GND CKT
CHECKING THE FUEL PRESSURE
CHECKING MAP SENSOR
RUNS ROUGH/UNSTABLE/
ERRATIC IDLECHECKING PCM POWER AND GND CKT
CHECKING THE FUEL PRESSURE
CHECKING ECT SENSOR
CHECKING THROTTLE POSITION SENSOR
CHECKING MAP SENSOR
CHECKING IDLE AIR CONTROL MOTOR OPERATION
CHECKING IAT SENSOR
9
GENERAL INFORMATION

SYMPTOM DIAGNOSTIC TEST
POOR FUEL ECONOMY CHECKING PCM POWER AND GND CKT
CHECKING THE FUEL PRESSURE
CHECKING ECT SENSOR
CHECKING THROTTLE POSITION SENSOR
CHECKING MAP SENSOR
CHECKING IDLE AIR CONTROL MOTOR OPERATION
CHECKING IAT SENSOR
3.4 USING THE DRBIIIT
Refer to the DRBIIItuser 's guide for instructions
and assistance with reading DTC's, erasing DTC's,
and other DRBIIItfunctions.
3.5 DRBIIITERROR MESSAGES AND
BLANK SCREEN
Under normal operation, the DRBIIItwill dis-
play one of only two error messages:
± User-Requested WARM Boot or User-
Requested COLD Boot
ver: 2.14
date: 26 Jul93
file: key_itf.cc
date: Jul 26 1993
line: 548
err: 0x1
User-Requested COLD Boot
Press MORE to switch between this display
and the application screen.
Press F4 when done noting information.
3.5.1 DRBIIITDOES NOT POWER UP
If the LED's do not light or no sound is emitted at
start up, check for loose cable connections or a bad
cable. Check the vehicle battery voltage (data link
connector cavity 16). A minimum of 11 volts is
required to adequately power the DRBIIIt.
If all connections are proper between the
DRBIIItand the vehicle or other devices, and the
vehicle battery is fully charged, and inoperative
DRBIIItmay be the result of faulty cable or vehicle
wiring.
3.5.2 DISPLAY IS NOT VISIBLE
Low temperatures will affect the visibility of the
display. Adjust the contrast to compensate for this
condition
4.0 DISCLAIMERS, SAFETY,
WARNINGS
4.1 DISCLAIMERS
All information, illustrations, and specifications
contained in this manual are based on the latest
information available at the time of publication.
The right is reserved to make changes at any time
without notice.
4.2 SAFETY
4.2.1 TECHNICIAN SAFETY INFORMATION
WARNING: ENGINES PRODUCE CARBON
MONOXIDE THAT IS ODORLESS, CAUSES
SLOWER REACTION TIME, AND CAN LEAD
TO SERIOUS INJURY. WHEN THE ENGINE IS
OPERATING, KEEP SERVICE AREAS WELL
VENTILATED OR ATTACH THE VEHICLE
EXHAUST SYSTEM TO THE SHOP EXHAUST
REMOVAL SYSTEM.
Set the parking brake and block the wheels before
testing or repairing the vehicle. It is especially
10
GENERAL INFORMATION

When testing voltage or continuity at any control
module, use the terminal side (not the wire end) of
the connector. Do not probe a wire through the
insulation; this will damage it and eventually cause
it to fail because of corrosion.
Be careful when performing electrical tests so as
to prevent accidental shorting of terminals. Such
mistakes can damage fuses or components. Also, a
second DTC could be set, making diagnosis of the
original problem more difficult.
5.0 REQUIRED TOOLS AND
EQUIPMENT
DRBIIIt(diagnostic read-out box) scan tool
Evaporative System Diagnostic Kit #6917
fuel filler adapter #8382
fuel pressure adapter (C-6631) or #6539
fuel pressure kit (C-4799-B) or #5069
fuel release hose (C-4799-1)
Min Air flow fitting #6714
jumper wires
ohmmeter
oscilloscope
vacuum gauge
voltmeter
12 volt test light minimum 25 ohms resistance
with probe #6801
CAUTION: A 12 VOLT TEST LIGHT SHOULD
NOT BE USED FOR THE FOLLOWING
CIRCUITS, DAMAGE TO THE POWERTRAIN
CONTROLLER WILL OCCUR.
²5 Volt Supply
²8 Volt Supply
²J1850 PCI Bus
²CCD Bus
²CKP Sensor Signal
²CMP Sensor Signal
²Vehicle Speed Sensor Signal
²O2 Sensor Signal
6.0 GLOSSARY OF TERMS
ABSanti-lock brake system
backfire,
popbackfuel ignites in either the intake or
the exhaust system
CKPcrank position sensor
CMPcamshaft position sensorcuts out,
missesa steady pulsation or the inability of
the engine to maintain a consistent
rpm
DLCdata link connector (previously
called engine diagnostic connector)
detona-
tion,
spark
knocka mild to severe ping, especially un-
der loaded engine conditions
ECTengine coolant temperature sensor
EGRexhaust gas recirculation valve
genera-
torpreviously called alternator
hard
startThe engine takes longer than usual
to start, even though it is able to
crank normally.
hesita-
tion, sag,
stumbleThere is a momentary lack of re-
sponse when the throttle is opened.
This can occur at all vehicle speeds.
If it is severe enough, the engine
may stall.
IATintake air temperature sensor
IACidle air control motor
JTECCombined engine and transmission
control module
lack of
power,
sluggishThe engine has less than expected
power, with little or no increase in
vehicle speed when the throttle is
opened.
LDPleak detection pump
MAPmanifold absolute pressure sensor
MILmalfunction indicator lamp
MTVmanifold tuning valve
O2Soxygen sensor
PCIprogrammable communication inter-
face
PCMpowertrain control module
PCVpositive crankcase ventilation
PEPperipheral expansion port
poor fuel
economyThere is significantly less fuel mile-
age than other vehicles of the same
design ad configuration
12
GENERAL INFORMATION

rough,
unstable,
or er-
ratic idle
stallingThe engine runs unevenly at idle
and causes the engine to shake if it
is severe enough. The engine idle
rpm may vary (called hunting). This
condition may cause stalling if it is
severe enough.
SBECsingle board engine controller
SKIMsentry key immobilizer module
SKISsentry key immobilizer systemstart &
stallThe engine starts but immediately
dies.
surgeengine rpm fluctuation without cor-
responding change in throttle posi-
tion sensor
TPSthrottle position sensor
TRStransmission range sensor
VSSvehicle speed sensor/signal
13
GENERAL INFORMATION

Symptom:
P0071 - AMBIENT TEMP SENSOR PERFORMANCE
When Monitored and Set Condition:
P0071 - AMBIENT TEMP SENSOR PERFORMANCE
When Monitored: With the ignition on. Coolant Temperature greater than 71ÉC (160ÉF)
No Inlet Air Temperature Sensor Faults present
Set Condition: After 5 warm cycles have occurred (coolant increases from great than
4.4ÉC (40ÉF) to a minimum of 71ÉC (160ÉF) and the odometer mileage has increased 196.6
miles and the Inlet Air Temperature has increased less than 3ÉC (5.4ÉF) change in
temperature. Two trip fault.
POSSIBLE CAUSES
INTERMITTENT CONDITION
IAT SENSOR VOLTAGE BELOW 1.0 VOLTS
SENSOR GROUND CIRCUIT VOLTAGE DROP
IAT SENSOR SIGNAL CIRCUIT VOLTAGE DROP
PCM
TEST ACTION APPLICABILITY
1NOTE: If DTC P1192 or P1193 have set along with P0071, diagnose P1192 or
P1193 first before continuing.
Turn the ignition on.
With the DRBIIIt, read DTC's.
Is the Good Trip displayed and equal to zero?All
Ye s®Go To 2
No®Go To 7
2 Turn the ignition off.
Disconnect the Inlet Air Temperature Sensor harness connector.
Turn the ignition on.
With the DRBIIIt, read the IAT voltage.
Is the voltage above 4.6 volts?All
Ye s®Go To 3
No®Go To 4
3 Turn the ignition off.
Disconnect the Inlet Air Temperature Sensor harness connector.
Using a jumper wire, jumper across the IAT Sensor harness connector.
Turn the ignition on.
With the DRBIIIt, read the IAT voltage.
Is the voltage below 1.0 volt?All
Ye s®Replace the Inlet Air Temperature Sensor.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
No®Go To 4
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DRIVEABILITY - GAS