air condition OPEL FRONTERA 1998 Workshop Manual

6E–6
4JX1–TC ENGINE DRIVEABILITY AND EMISSIONS
Removal Procedure 6E–212. . . . . . . . . . . . . . . . . . . .
Installation Procedure 6E–212. . . . . . . . . . . . . . . . . .
Fuel Filter Cap 6E–213. . . . . . . . . . . . . . . . . . . . . . . . . .
General Description 6E–213. . . . . . . . . . . . . . . . . . . .
Inspection Procedure 6E–213. . . . . . . . . . . . . . . . . .
Fuel Filter 6E–213. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removal and Installation Procedure 6E–213. . . . . .
Fuel Gauge Unit 6E–213. . . . . . . . . . . . . . . . . . . . . . . .
Removal Procedure 6E–213. . . . . . . . . . . . . . . . . . . .
Installation Procedure 6E–214. . . . . . . . . . . . . . . . . .
Fuel Injectors 6E–214. . . . . . . . . . . . . . . . . . . . . . . . . . .
Removal and Installation Procedure 6E–214. . . . . .
Fuel Temperature Sensor 6E–214. . . . . . . . . . . . . . . .
Removal Procedure 6E–214. . . . . . . . . . . . . . . . . . . .
Installation Procedure 6E–215. . . . . . . . . . . . . . . . . .
Rail Pressure (RP) Sensor 6E–216. . . . . . . . . . . . . . .
Removal Procedure 6E–216. . . . . . . . . . . . . . . . . . . .
Installation Procedure 6E–216. . . . . . . . . . . . . . . . . .
Fuel Tank 6E–216. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removal Procedure 6E–216. . . . . . . . . . . . . . . . . . . .
Throttle Body (TB) 6E–217. . . . . . . . . . . . . . . . . . . . . . .
Removal Procedure 6E–217. . . . . . . . . . . . . . . . . . . .
Installation Procedure 6E–217. . . . . . . . . . . . . . . . . .
Air Conditioning (A/C) Relay 6E–217. . . . . . . . . . . . . .
Removal Procedure 6E–217. . . . . . . . . . . . . . . . . . . .
Installation Procedure 6E–217. . . . . . . . . . . . . . . . . .
Exhaust Gas Recirculation (EGR) Vacuum
Switch Valve (VSV) 6E–217. . . . . . . . . . . . . . . . . . . . .
Removal Procedure 6E–217. . . . . . . . . . . . . . . . . . . .
Installation Procedure 6E–218. . . . . . . . . . . . . . . . . .
Electronic Vacuum Regurating Valve (EVRV) 6E–219
Removal Procedure 6E–219. . . . . . . . . . . . . . . . . . . .
Installation Procedure 6E–220. . . . . . . . . . . . . . . . . .
Wiring and Connectors 6E–220. . . . . . . . . . . . . . . . . . .
Wiring Harness Service 6E–220. . . . . . . . . . . . . . . .
Connectors and Terminals 6E–220. . . . . . . . . . . . . .
Wire Harness Repair: Twisted Shielded
Cable 6E–220. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removal Procedure 6E–220. . . . . . . . . . . . . . . . . . . .
Installation Procedure 6E–221. . . . . . . . . . . . . . . . . .
Twisted Leads 6E–221. . . . . . . . . . . . . . . . . . . . . . . . . .
Removal Procedure 6E–221. . . . . . . . . . . . . . . . . . . .
Installation Procedure 6E–222. . . . . . . . . . . . . . . . . .
Weather-Pack Connector 6E–223. . . . . . . . . . . . . . . . .
Tools Required 6E–223. . . . . . . . . . . . . . . . . . . . . . . .
Removal Procedure 6E–223. . . . . . . . . . . . . . . . . . . . Installation Procedure 6E–223. . . . . . . . . . . . . . . . . .
Com-Pack III 6E–224. . . . . . . . . . . . . . . . . . . . . . . . . . .
General Information 6E–224. . . . . . . . . . . . . . . . . . . .
Metri-Pack 6E–224. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tools Required 6E–224. . . . . . . . . . . . . . . . . . . . . . . .
Removal Procedure 6E–224
. . . . . . . . . . . . . . . . . . . .
Installation Procedure 6E–224. . . . . . . . . . . . . . . . . .
General Description
(ECM and Sensors) 6E–225. . . . . . . . . . . . . . . . . . . . .
57X Reference ECM Input 6E–225. . . . . . . . . . . . . .
A/C Request Signal 6E–225. . . . . . . . . . . . . . . . . . . .
Crankshaft Position (CKP) Sensor 6E–225. . . . . . .
Camshaft Position (CMP) Sensor and
Signal 6E–225. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine Coolant Temperature (ECT) Sensor 6E–225
Electrically Erasable Programmable Read
Only Memory (EEPROM) 6E–225. . . . . . . . . . . . . .
Intake Air Temperature (IAT) Sensor 6E–225. . . . .
Manifold Absolute Pressure (MAP) Sensor 6E–226
Engine Control Module (ECM) 6E–226. . . . . . . . . . .
ECM Function 6E–226. . . . . . . . . . . . . . . . . . . . . . . . .
ECM Components 6E–226. . . . . . . . . . . . . . . . . . . . .
ECM Voltage Description 6E–226. . . . . . . . . . . . . . .
ECM Input/Outputs 6E–226. . . . . . . . . . . . . . . . . . . .
ECM Service Precautions 6E–227. . . . . . . . . . . . . .
Intake Throttle Position (ITP) Sensor 6E–227. . . . .
Transmission Range Switch 6E–227. . . . . . . . . . . . .
Accelerator Position Sensor (AP) 6E–227. . . . . . . .
Aftermarket Electrical and Vacuum
Equipment 6E–227. . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrostatic Discharge Damage 6E–227. . . . . . . . .
General Description (Air Induction) 6E–228. . . . . . . .
Air Induction System 6E–228. . . . . . . . . . . . . . . . . . .
General Description (Fuel Metering) 6E–228. . . . . . .
Deceleration Mode 6E–228. . . . . . . . . . . . . . . . . . . .
Fuel Injector 6E–228. . . . . . . . . . . . . . . . . . . . . . . . . .
Fuel Metering System Components 6E–228. . . . . .
A/C Clutch Diagnosis 6E–228. . . . . . . . . . . . . . . . . . . .
A/C Request Signal 6E–228. . . . . . . . . . . . . . . . . . . .
General Description Exhaust Gas
Recirculation (EGR) System 6E–228. . . . . . . . . . . . .
EGR Purpose 6E–228. . . . . . . . . . . . . . . . . . . . . . . . .
Fuse and Relay Panel
(Underhood Electrical Center) RHD 6E–229. . . . . . .
Fuse and Relay Panel
(Underhood Electrical Center) LHD 6E–230. . . . . . .

6E–23 4JX1–TC ENGINE DRIVEABILITY AND EMISSIONS
Abbreviations Charts
List of abbreviations which may be used in this section.
Abbreviations
Te r mAbbreviationsTe r m
A/CAir ConditionerBLKBlack
A/TAutomatic TransmissionBLUBlue
ACCAccessoryBRNBrown
APAccel PositionGRNGreen
ASMAssemblyGRYGray
CKPCrank PositionLT B L ULight Blue
CMPCam PositionLT G R NLight Green
DLCData Link ConnectorORNOrange
DTCDiagnosis Trouble CodePNKPink
DVMDigital Volt MeterREDRed
ECMEngine Control ModuleVIOViolet
ECTEngine Coolant TemperatureWHTWhite
EGRExhaust Gas RecircurationYELYe l l o w
EVRVElectric Vacuum Regulating Valve
EXHExhaust
FTFuel Temperature
IATIntake Air Temperature
IGIgnition
ITPIntake Throttle Position
M/TManual Transmission
MAPManifold Absolute Pressure
MILMulfunction Indicator Lamp
OBDOn-Board Diagnostic
OTOil Temperature
QOSQuick on Start System
QWSQuick Warming-Up System
RPRail Pressure
RPCVRail Pressure Control Valve
SRSSupplemental Restraint System
STStart
SWSwitch
TEMPTemperature
TODTorque on Demand
VSSVehicle Speed Sensor
VSVVacuum Switching Valve
HEUIHydraulically Actuated Electronically Controlled Unit
InjectorInjector

6E–24
4JX1–TC ENGINE DRIVEABILITY AND EMISSIONS
Diagnosis
Strategy-Based Diagnostics
Strategy-Based Diagnostics
The strategy-based diagnostic is a uniform approach to
repair all Electrical/Electronic (E/E) systems. The
diagnostic flow can always be used to resolve an E/E
system problem and is a starting point when repairs are
necessary. The following steps will instruct the technician
how to proceed with a diagnosis:
1. Verify the customer complaint.
To verify the customer complaint, the technician
should know the normal operation of the system.
2. Perform preliminary checks.
Conduct a thorough visual inspection.
Review the service history.
Detect unusual sounds or odors.
Gather diagnostic trouble code information to
achieve an effective repair.
3. Check bulletins and other service information.
This includes videos, newsletters, etc.
4. Refer to service information (manual) system
check(s).
“System checks” contain information on a system
that may not be supported by one or more DTCs.
System checks verify proper operation of the
system. This will lead the technician in an
organized approach to diagnostics.
5. Refer to service diagnostics.
DTC Stored
Follow the designated DTC chart exactly to make an
effective repair.
No DTC
Select the symptom from the symptom tables. Follow the
diagnostic paths or suggestions to complete the repair.
You may refer to the applicable component/system check
in the system checks.
No Matching Symptom
1. Analyze the complaint.
2. Develop a plan for diagnostics.
3. Utilize the wiring diagrams and the theory of
operation.
Call technical assistance for similar cases where repair
history may be available. Combine technician knowledge
with efficient use of the available service information.
Intermittents
Conditions that are not always present are called
intermittents. To resolve intermittents, perform the
following steps:
1. Observe history DTCs, DTC modes, and freezeframe
data.2. Evaluate the symptoms and the conditions described
by the customer.
3. Use a check sheet or other method to identify the
circuit or electrical system component.
4. Follow the suggestions for intermittent diagnosis
found in the service documentation.
Most scan tools, such as the Tech 2 and the DVM, have
data-capturing capabilities that can assist in detecting
intermittents.
No Trouble Found
This condition exists when the vehicle is found to operate
normally. The condition described by the customer may
be normal. Verify the customer complaint against another
vehicle that is operating normally. The condition may be
intermittent. Verify the complaint under the conditions
described by the customer before releasing the vehicle.
1. Re-examine the complaint.
When the complaint cannot be successfully found or
isolated, a re-evaluation is necessary. The complaint
should be re-verified and could be intermittent as
defined in
Intermittents, or could be normal.
2. Repair and verify.
After isolating the cause, the repairs should be made.
Validate for proper operation and verify that the
symptom has been corrected. This may involve road
testing or other methods to verify that the complaint
has been resolved under the following conditions:
Conditions noted by the customer.
If a DTC was diagnosed, verify a repair by
duplicating conditions present when the DTC was
set as noted in the Failure Records or Freeze
Frame data.
Verifying Vehicle Repair
Verification of the vehicle repair will be more
comprehensive for vehicles with OBD system
diagnostics. Following a repair, the technician should
perform the following steps:
IMPORTANT:Follow the steps below when you verify
repairs on OBD systems. Failure to follow these steps
could result in unnecessary repairs.
1. Review and record the Failure Records and the
Freeze Frame data for the DTC which has been
diagnosed (Freeze Frame data will only be stored for
the MIL (“Check Engine” lamp) has been requested).
2. Clear the DTC(s).
3. Operate the vehicle within conditions noted in the
Failure Records and Freeze Frame data.
4. Monitor the DTC status information for the specific
DTC which has been diagnosed until the diagnostic
test associated with that DTC runs.

6E–25 4JX1–TC ENGINE DRIVEABILITY AND EMISSIONS
General Service Information
Serviceability Issues
Non-OEM Parts
All of the OBD diagnostics have been calibrated to run
with OEM parts. Accordingly, if commercially sold sensor
or switch is installed, it makes a wrong diagnosis and turn
on the MIL (“Check Engine” lamp).
Aftermarket electronics, such as cellular phones,
stereos, and anti-theft devices, may radiate EMI into the
control system if they are improperly installed. This may
cause a false sensor reading and turn on the MIL (“Check
Engine” lamp).
Poor Vehicle Maintenance
The sensitivity of OBD diagnostics will cause the MIL
(“Check Engine” lamp) to turn on if the vehicle is not
maintained properly. Restricted oil filters, fuel filters, and
crankcase deposits due to lack of oil changes or improper
oil viscosity can trigger actual vehicle faults that were not
previously monitored prior to OBD. Poor vehicle
maintenance can not be classified as a “non-vehicle
fault”, but with the sensitivity of OBD diagnostics, vehicle
maintenance schedules must be more closely followed.
Related System Faults
Many of the OBD system diagnostics will not run if the
ECM detects a fault on a related system or component.
Visual/Physical Engine Compartment
Inspection
Perform a careful visual and physical engine
compartment inspection when performing any diagnostic
procedure or diagnosing the cause of an emission test
failure. This can often lead to repairing a problem without
further steps. Use the following guidelines when
performing a visual/physical inspection:
Inspect all vacuum hoses for punches, cuts,
disconnects, and correct routing.
Inspect hoses that are difficult to see behind other
components.
Inspect all wires in the engine compartment for proper
connections, burned or chafed spots, pinched wires,
contact with sharp edges or contact with hot exhaust
manifolds or pipes.
Basic Knowledge of Tools Required
NOTE: Lack of basic knowledge of this powertrain when
performing diagnostic procedures could result in an
incorrect diagnosis or damage to powertrain
components. Do not attempt to diagnose a powertrain
problem without this basic knowledge.
A basic understanding of hand tools is necessary to effec-
tively use this section of the Service Manual.
Serial Data Communications
Class II Serial Data Communications
This vehicle utilizes the “Class II” communication system.
Each bit of information can have one of two lengths: longor short. This allows vehicle wiring to be reduced by
transmitting and receiving multiple signals over a single
wire. The messages carried on Class II data streams are
also prioritized. If two messages attempt to establish
communications on the data line at the same time, only
the message with higher priority will continue. The device
with the lower priority message must wait.
On this vehicle the Tech 2 displays the actual values for
vehicle parameters. It will not be necessary to perform
any conversions from coded values to actual values.
On-Board Diagnostic (OBD)
On-Board Diagnostic Tests
A diagnostic test is a series of steps, the result of which is
a pass or fail reported to the diagnostic executive. When
a diagnostic test reports a pass result, the diagnostic
executive records the following data:
The diagnostic test has been completed since the last
ignition cycle.
The diagnostic test has passed during the current
ignition cycle.
The fault identified by the diagnostic test is not
currently active.
When a diagnostic test reports a fail result, the diagnostic
executive records the following data:
The diagnostic test has been completed since the last
ignition cycle.
The fault identified by the diagnostic test is currently
active.
The fault has been active during this ignition cycle.
The operating conditions at the time of the failure.
Comprehensive Component Monitor
Diagnostic Operation
Comprehensive component monitoring diagnostics are
required to operate engine properly.
Input Components:
Input components are monitored for circuit continuity and
out-of-range values. This includes rationality checking.
Rationality checking refers to indicating a fault when the
signal from a sensor does not seem reasonable. Accel
Position (AP) sensor that indicates high throttle position
at low engine loads or MAP voltage. Input components
may include, but are not limited to the following sensors:
Intake Air Temperature (IAT) Sensor
Crankshaft Position (CKP) Sensor
Intake throttle Position (ITP) Sensor
Engine Coolant Temperature (ECT) Sensor
Camshaft Position (CMP) Sensor
Manifold absolute Pressure (MAP) Sensor
Accel Position Sensor
Fuel Temp Sensor
Rail Pressure Sensor
Oil Temp Sensor
EGR Pressure Sensor
Vehicle Speed Sensor

6E–27 4JX1–TC ENGINE DRIVEABILITY AND EMISSIONS
Non-Emissions related
Dose not request illumination of any lamp
Stores a History DTC on the first trip with a fail
Stores Fail Record when test fails
Updates the Fail Record each time the diagnostic test
fails
Storing and Erasing Freeze Frame Data and Failure
Records
The data captured is called Freeze Frame data. The
Freeze Frame data is very similar to a single record of
operating conditions. Whenever the MIL is illuminated,
the corresponding record of operating conditions is
recorded to the Freeze Frame buffer.
Data from these faults take precedence over data
associated with any other fault. The Freeze Frame data
will not be erased unless the associated history DTC is
cleared.
Each time a diagnostic test reports a failure, the current
engine operating conditions are recorded in the
Failure
Records
buffer. A subsequent failure will update the
recorded operating conditions. The following operating
conditions for the diagnostic test which failed
typically
include the following parameters:
Engine Speed
Engine Load
Engine Coolant Temperature
Vehicle Speed
Intake Throttle Position
MAP
Injector Base Pulse Width
Loop Status
Data Link Connector (DLC)
The provision for communication with the contorl module
is the Data Link Connector (DLC). It is located at behind
the lower front instrument panel. The DLC is used to
connect to a Tech 2. Some common uses of the Tech 2
are listed below:
Identifying stored Diagnostic Trouble Codes (DTCs).
Clearing DTCs.
Performing out put control tests.
Reading serial data.
060RW046
Verifying Vehicle Repair
Verification of vehicle repair will be more comprehensive
for vehicles with OBD system diagnostic. Following a
repair, the technician should perform the following steps:
1. Review and record the Fail Records and/or Freeze
Frame data for the DTC which has been diagnosed.
2. Clear DTC(s).
3. Operate the vehicle within conditions noted in the Fail
Records and/or Freeze Frame data.
4. Monitor the DTC status information for the specific
DTC which has been diagnosed until the diagnostic
test associated with that DTC runs.
Following these steps are very important in verifying
repairs on OBD systems. Failure to follow these steps
could result in unnecessary repairs.
Reading Flash Diagnostic Trouble Codes
The provision for communicating with the Engine Control
Module (ECM) is the Data Link Connector (DLC). The
DLC is located in the front console box. It is used in the
assembly plant to receive information in checking that the
engine is operating properly before it leaves the plant.
The diagnostic trouble code(s) (DTCs) stored in the
ECM’s memory can be read either through a hand-held
diagnostic scanner plugged into the DLC or by counting
the number of flashes of the “Check Engine” Malfunction
Indicator Lamp (MIL) when the diagnostic test terminal of
the DLC is grounded. The DLC terminal “6” (diagnostic
request) is pulled “Low” (grounded) by jumpering to DLC
terminal “4”, which is a ground wire.
This will signal the ECM that you want to “flash” DTC(s), if
any are present. Once terminals “4” and “6” have been
connected, the ignition switch must be moved to the “ON”
position, with the engine not running.
The “Check Engine”MIL will indicate a DTC three times if
a DTC is present. If more than one DTC has been stored

6E–39 4JX1–TC ENGINE DRIVEABILITY AND EMISSIONS
Engine Control Module ECM
Diagnosis
To read and clear diagnostic trouble codes, use a Tech 2.
IMPORTANT:Use of a Tech 2 is recommended to clear
diagnostic trouble codes from the ECM memory.
Diagnostic trouble codes can also be cleared by turning
the ignition “OFF” and disconnecting the battery power
from the ECM for 30 seconds. Turning off the ignition and
disconnecting the battery power from the ECM will cause
all diagnostic information in the ECM memory to be
cleared. Therefore, all the diagnostic tests will have to be
re-run.
Since the ECM can have a failure which may affect only
one circuit, following the diagnostic procedures in this
section will determine which circuit has a problem and
where it is.
If a diagnostic chart indicates that the ECM connections
or the ECM is the cause of a problem, and the ECM is
replaced, but this does not correct the problem, one of the
following may be the reason:
There is a problem with the ECM terminal
connections. The terminals may have to be removed
from the connector in order to check them properly.
The problem is intermittent. This means that the
problem is not present at the time the system is being
checked. In this case, refer to the
Symptoms portion
of the manual and make a careful physical inspection
of all components and wiring associated with the
affected system.
There is a shorted solenoid, relay coil, or harness.
Solenoids and relays are turned “ON” and “OFF” by
the ECM using internal electronic switches called
drivers. A shorted solenoid, relay coil, or harness will
not damage the ECM but will cause the solenoid or
relay to be inoperative.
Multiple ECM Information Sensor
DTCS Set
Circuit Description
The Engine Control Module ECM monitors various
sensors to determine the engine operating conditions.
The ECM controls fuel delivery, spark advance,
transmission operation, and emission control device
operation based on the sensor inputs.
The ECM provides a sensor ground to all of the sensors.
The ECM applies 5 volts through a pull-up resistor, and
determines the status of the following sensors by
monitoring the voltage present between the 5-volt supply
and the resistor:
The fuel temperature (FT) sensor
The engine coolant temperature (ECT) sensor
The Intake air temperature (IAT) sensor
The ECM provides the following sensors with a 5-volt
reference and a sensor ground signal:
The Intake throttle position sensor
The manifold absolute pressure sensor
The rail pressure sensor
The accelerator position sensor
The oil temperature sensor
The camshaft position sensor
The crankshaft position sensor
The EGR pressure sensor
The ECM monitors the signals from these sensors in
order to determine their operating status.
Diagnostic Aids
IMPORTANT:Be sure to inspect ECM and engine
grounds for being secure and clean.
A short to voltage in one of the sensor input circuits may
cause one or more of the following DTCs to be set:
P0337
P0342
P1193
P1404
P1405
P1488
IMPORTANT:If a sensor input circuit has been shorted
to voltage, ensure that the sensor is not damaged. A
damaged sensor will continue to indicate a high or low
voltage after the affected circuit has been repaired. If the
sensor has been damaged, replace it.
An open in the sensor ground circuit between the ECM
and the splice will cause one or more of the following
DTCs to be set:
P0337
P0342
P0117
A short to ground in the 5-volt reference A or B circuit will
cause one or more of the following DTCs to be set:
P0112
P0117
P0182
P0197
An open in the 5-volt reference circuit A, between the
ECM and the splice will cause one or more of the following
DTCs to be set:
P0107
P0405
P1194
P0122
An open in the 5-volt reference circuit B, between the
ECM and the splice will cause one or more of the following
DTCs to be set:
P1485
Check for the following conditions:
Poor connection at ECM. Inspect the harness
connectors for backed-out terminals, improper
mating, broken locks, improperly formed or damage
terminals, and a poor terminal-to-wire connection.
Damaged harness. Inspect the wiring harness for
damage. If the harness is not damaged, observe an
affected sensor’s displayed value on the Tech 2 with
the ignition “ON” and the engine “OFF” while you
move the connectors and the wiring harnesses
related to the following sensors:
ECT Sensor

6E–40
4JX1–TC ENGINE DRIVEABILITY AND EMISSIONS
MAP Sensor
CMP Sensor
CKP Sensor
EGR Pressure Sensor
EGR VSV
RPCV
IAT Sensor
Intake Throttle Motor
Fuel Temperature Sensor
Oil Temperature Sensor
Rail Pressure Sensor
Multiple ECM Information Sensor DTCs Set
StepActionVa l u e ( s )Ye sNo
1Was the “On-Board Diagnostic (OBD) System Check”
performed?
—Go to Step 2
Go to OBD
System
Check
21. Turn the ignition “OFF,” disconnect the ECM.
2. Turn the ignition “ON,” check the 5 volt reference D
circuit for the following conditions:
D poor connection at the ECM.
An open between the ECM connector and the
splice.
D short to ground.
D short to voltage.
Is there an open or short?
—Go to Step 3Go to Step 4
3Repair the open or short.
Is the action complete?
—Verify repair—
4Check the sensor ground circuit for the following
conditions:
A poor connection at the ECM or the affected
sensors.
An open between the ECM connector and the
affected sensors.
Is there an open or a poor connection?
—Go to Step 5Go to Step 6
5Repair the open or the poor connection.
Is the action complete?
—Verify repairGo to Step 6
6Replace the ECM (Refer to the Data Programming in
Case of ECM change).
Is the action complete?
—
Go to OBD
System
Check
—

6E–41 4JX1–TC ENGINE DRIVEABILITY AND EMISSIONS
EGR (Exhaust Gas Recirculation)
Diagnosis
A diagnosis of the EGR system is covered by DTC
P1403.
EGR VSV circuit diagnosis is covered by DTC P1404.
EGR pressure sensor diagnosis is covered by DTC
P405 and/or P406.
EGR EVRV circuit diagnosis is covered by DTC
P1405. Refer to the DTC charts.
Tech 2 Data Definitions and Ranges
A/C CLUTCH–Tech 2 Displays ON or OFF–
Indicates whether the A/C has commanded the A/C
clutch ON.
MAP kPa — Tech 2 Range 10-105 kPa/0.00-5.00
Vo l t s —
The manifold absolute pressure reading is determined
from the MAP sensor signal monitored during key up and
wide open throttle (WOT) conditions. The manifold
absolute pressure is used to compensate for altitude
differences and is normally displayed around “61-104”
depending on altitude and manifold absolute pressure.
CMP ACT. COUNTER –Cam Position
DESIRED IDLE — Tech 2 Range 0-3187 RPM —
The idle speed that the ECM is commanding. The ECM
will compensate for various engine loads based on engine
coolant temperature, to keep the engine at the desired
speed.
ECT — (Engine Coolant Temperature) Tech 2
Range –40
C to 151C (–40F to 304F) —
The engine coolant temperature (ECT) is mounted in the
coolant stream and sends engine temperature
information to the ECM. The ECM applies 5 volts to the
ECT sensor circuit. The sensor is a thermistor which
changes internal resistance as temperature changes.
When the sensor is cold (high resistance), the ECM
monitors a high signal voltage and interprets that as a cold
engine. As the sensor warms (decreasing resistance),
the voltage signal will decrease and the ECM will interpret
the lower voltage as a warm engine.
ENGINE RUN TIME — Tech 2 Range
00:00:00-99:99:99 Hrs:Min:Sec —
Indicates the time elapsed since the engine was started.
If the engine is stopped, engine run time will be reset to
00:00:00.
ENGINE SPEED — Range 0-9999 RPM —
Engine speed is computed by the ECM from the 57X
reference input. It should remain close to desired idle
under various engine loads with engine idling.Air Intake Valve meter POSITION — Tech 2 Range
0-100 % —
IAT (INTAKE AIR TEMPERATURE)— Tech 2 Range
–40
C to 151C (–40F to 304F) —
The ECM converts the resistance of the intake air
temperature sensor to degrees. Intake air temperature
(IAT) is used by the ECM to adjust fuel delivery and spark
timing according to incoming air density.
MAP — Tech 2 Range 10-105 kPa (0.00-4.97 Volts)—
The manifold absolute pressure (MAP) sensor measures
the change in the boost pressure.
MIL — Tech 2 Displays ON or OFF —
Indicates the ECM commanded state of the malfunction
indicator lamp.
AP — Tech 2 Range 0%-100% —
AP (Accelerator position) angle is computed by the ECM
from the AP sensor voltage. AP angle should display
“0%” at idle and “100%” at wide open throttle.
AP SENSOR — Tech 2 Range 0.00-5.00 Volts —
The voltage being monitored by the ECM on the AP
sensor signal circuit.
VEHICLE SPEED—Tech 2 Range 0-255 km/h (0-155
mph)–
The vehicle speed sensor signal is converted into km/h
and mph for display.
Typical Scan Data Values
Use the Typical Scan Data Values Table only after the
On-Board Diagnostic System Check has been
completed, no DTC(s) were noted, and you have
determined that the on-board diagnostics are functioning
properly. Tech 2 values from a properly-running engine
may be used for comparison with the engine you are
diagnosing. The typical scan data values represent
values that would be seen on a normally-running engine.
NOTE: A Tech 2 that displays faulty data should not be
used, and the problem should be reported to the Tech 2
manufacturer. Use of a faulty Tech 2 can result in
misdiagnosis and unnecessary replacement of parts.
Only the parameters listed below are referred to in this
service manual for use in diagnosis. For further
information on using the Tech 2 to diagnose the ECM and
related sensors, refer to the applicable reference section
listed below. If all values are within the typical range
described below, refer to the
Symptoms section for
diagnosis.
Test Conditions
Engine running, lower radiator hose hot, transmission in
park or neutral, accessaries off, brake not applied and air
conditioning off.

6E–50
4JX1–TC ENGINE DRIVEABILITY AND EMISSIONS
Engine Cranks But Will Not Run
StepNo Ye s Va l u e ( s ) Action
10Refer to Engine Mechanical Diagnosis to diagnose the
following conditions:
Faulty camshaft drive belts
Leaking or sticky valves or rings
Excessive valve deposits
Weak valve springs
Incorrect valve timing
Leaking head gasket
Is the action complete?
—Verify repairGo to Step 11
11Observe the “Engine Speed” data display on the Tech 2
while cranking the engine.
Is the engine RPM indicated? (If the Tech 2 is normally
powered from the cigarette lighter socket, and if the
Tech 2 display goes blank while cranking the engine, it
will be necessary to power the Tech 2 directly from the
vehicle battery.)
—Go to Step 12Go to Step 17
121. At the ECM (female) side of the connector
mentioned in step, connect a test light between the
ignition + terminal and one of the injector driver
circuits at the same connector.
2. Ignition “ON.”
3. Observe the test light, and repeat the test for each
injector driver circuit by oscilloscope.
Did the test light stay on when checking any of the 4
injector driver circuits?
—Go to Step 13Go to Step 15
131. Ignition “OFF,” disconnect the ECM.
2. Ignition “ON,” observe the test light.
Is the test light “ON?”
—Go to Step 14Go to Step 16
14Locate and repair the short to ground in the injector
driver circuit.
Is the action complete?
—Verify repair—
15Check for an open injector driver circuit.
Was a problem found?
—Verify repairGo to Step 16
16Replace the ECM (Refer to the Data Programming in
Case of ECM change).
Is the action complete?
—Verify repair—
171. Raise the vehicle and disconnect the CKP sensor
harness.
2. Ignition “ON.”
3. With a test light to ground, probe the harness
ignition feed terminal.
Did the light illuminate?
—Go to Step 19Go to Step 18
18Check the ignition feed wire between the sensor and
the ECM for a short to ground or open circuit.
Is the action complete?
—Verify repair—

6E–60
4JX1–TC ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0112 (Flash DTC 23)
IAT Sensor Circuit Low Voltage
060RW129
Circuit Description
The Intake air temperature (IAT) sensor is a thermistor
which measures the temperature of the air entering the
engine. The Engine Control Module ECM applies 5 volts
through a pull-up resistor to the IAT sensor. When the
intake air is cold, the sensor resistance is high and the
ECM will monitor a high signal voltage on the IAT signal
circuit. If the intake air is warm, the sensor resistance is
lower, causing the ECM to monitor a lower voltage. DTC
P0112 will set when the ECM detects an excessively low
signal voltage on the Intake air temperature sensor signal
circuit.
Action Taken When the DTC Sets
The ECM will illuminate the malfunction indicator lamp
(MIL) the first time the fault is detected.
The ECM will store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.
Conditions for Clearing the MIL/DTC
DTC P0112 can be cleared by using the Tech 2 “Clear
Info” function or by disconnecting the ECM battery
feed.
Diagnostic Aids
Check for the following conditions:
Poor connection at ECM – Inspect harness connectors
for backed-out terminals, improper mating, broken
locks, improperly formed or damaged terminals, and
poor terminal-to-wire connection.
Damaged harness – Inspect the wiring harness for
damage. If the harness appears to be OK, observe the
IAT display on the Tech 2 while moving connectors and
wiring harnesses related to the IAT sensor. A change
in the IAT display will indicate the location of the fault.
If DTC P0112 cannot be duplicated, the information
included in the Failure Records data can be useful in
determining vehicle mileage since the DTC was last set.