1998 OPEL FRONTERA ABS

6E–338
ENGINE DRIVEABILITY AND EMISSIONS
RPM. A failure in the MAF sensor or circuit will set DTC
P0101, DTC P0102, or DTC P0103.
0007
Manifold Absolute Pressure (MAP) Sensor
The manifold absolute pressure (MAP) sensor responds
to changes in intake manifold pressure (vacuum). The
MAP sensor signal voltage to the PCM varies from below
2 volts at idle (high vacuum) to above 4 volts with the
ignition ON, engine not running or at wide-open throttle
(low vacuum).
The MAP sensor is used to determine the following:
Manifold pressure changes while the linear EGR flow
test diagnostic is being run. Refer to
DTC P0401.
Engine vacuum level for other diagnostics.
Barometric pressure (BARO).
If the PCM detects a voltage that is lower than the
possible range of the MAP sensor, DTC P0107 will be set.
A signal voltage higher than the possible range of the
sensor will set DTC P0108. An intermittent low or high
voltage will set DTC P1107 or DTC P1106, respectively.
The PCM can detect a shifted MAP sensor. The PCM
compares the MAP sensor signal to a calculated MAP
based on throttle position and various engine load factors.
If the PCM detects a MAP signal that varies excessively
above or below the calculated value, DTC P0106 will set.
055RW004
Powertrain Control Module (PCM)
The powertrain control module (PCM) is located in the
passenger compartment below the center console. The
PCM controls the following:
Fuel metering system.
Transmission shifting (automatic transmission only).
Ignition timing.
On-board diagnostics for powertrain functions.
The PCM constantly observes the information from
various sensors. The PCM controls the systems that
affect vehicle performance. The PCM performs the
diagnostic function of the system. It can recognize
operational problems, alert the driver through the MIL
(Service Engine Soon lamp), and store diagnostic trouble
codes (DTCs). DTCs identify the problem areas to aid the
technician in making repairs.
This engine uses 2 different control modules:
IPCM-6KT for automatic transmission-equipped
vehicles.
ISFI-6 for manual transmission-equipped vehicles.
PCM Function
The PCM supplies either 5 or 12 volts to power various
sensors or switches. The power is supplied through
resistances in the PCM which are so high in value that a
test light will not light when connected to the circuit. In
some cases, even an ordinary shop voltmeter will not give
an accurate reading because its resistance is too low.
Therefore, a digital voltmeter with at least 10 megohms
input impedance is required to ensure accurate voltage
readings. Tool J 39200 meets this requirement. The PCM
controls output circuits such as the injectors, IAC, cooling
fan relays, etc., by controlling the ground or the power
feed circuit through transistors of following device.
Output Driver Module (ODM)

6E–339 ENGINE DRIVEABILITY AND EMISSIONS
0005
PCM Components
The PCM is designed to maintain exhaust emission levels
to government mandated standards while providing
excellent driveability and fuel efficiency. The PCM
monitors numerous engine and vehicle functions via
electronic sensors such as the throttle position (TP)
sensor, heated oxygen sensor (HO2S), and vehicle
speed sensor (VSS). The PCM also controls certain
engine operations through the following:
Fuel injector control
Ignition control module
Knock sensor
Automatic transmission shift functions
Cruise control
A/C clutch control
PCM Voltage Description
The PCM supplies a buffered voltage to various switches
and sensors. It can do this because resistance in the
PCM is so high in value that a test light may not illuminate
when connected to the circuit. An ordinary shop
voltmeter may not give an accurate reading because the
voltmeter input impedance is too low. Use a 10-megohm
input impedance digital voltmeter (such as J 39200) to
assure accurate voltage readings.
The input/output devices in the PCM include
analog-to-digital converters, signal buffers, counters,
and special drivers. The PCM controls most components
with electronic switches which complete a ground circuit
when turned “ON.” These switches are arranged in
groups of 4 and 7, called either a surface-mounted quad
driver module (QDM), which can independently control up
to 4 output terminals, or QDMs which can independently
control up to 7 outputs. Not all outputs are always used.
PCM Input/Outputs
Inputs – Operating Conditions Read
Air Conditioning “ON” or “OFF”
Engine Coolant Temperature
Crankshaft Position
Exhaust Oxygen Content
Electronic Ignition
Manifold Absolute Pressure
Battery Voltage
Throttle Position
Vehicle Speed
Fuel Pump Voltage
Power Steering Pressure
Intake Air Temperature
Mass Air Flow
Engine Knock
Camshaft Position
Outputs – Systems Controlled
Exhaust Gas Recirculation (EGR)
Ignition Control
Fuel Control
Idle Air Control
Electric Fuel Pump
Air Conditioning
Diagnostics
– Malfunction Indicator Lamp (Service Engine Soon
lamp)
– Data Link Connector (DLC)
– Data Output
Transmission Control Module
Alternator Gain Control
PCM Service Precautions
The PCM is designed to withstand normal current draws
associated with vehicle operation. Avoid overloading any
circuit. When testing for opens and shorts, do not ground
or apply voltage to any of the PCM’s circuits unless
instructed to do so. These circuits should only be tested
Tech-2. The PCM should remain connected to the PCM
or to a recommended breakout box.
Reprogramming The PCM
The Trooper allow reprogramming of the PCM without
removing it from the vehicle . This provides a flexible and
cost-effective method of making changes in software
calibrations.
The service programming system (SPS) will not allow
incorrect software programming or incorrect calibration
changes.
Refer to the UBS 98model year Immobilizer Workshop
Manual.
Throttle Position (TP) Sensor
The throttle position (TP) sensor is a potentiometer
connected to the throttle shaft on the throttle body. The
PCM monitors the voltage on the signal line and
calculates throttle position. As the throttle valve angle is
changed (accelerator pedal moved), the TP sensor signal
also changes. At a closed throttle position, the output of

ENGINE MECHANICAL 6A – 11
Remove the radiator filler cap only when absolutely
necessary.
Always check the coolant level when the engine is cold.
Always refer to the chart at the left to determine the
correct cooling water to antifreeze solution mixing ratio.
Cooling System Inspection
Install a radiator filler cap tester to the radiator. Apply
testing pressure to the cooling system to check for
leakage.
The testing pressure must not exceed the specified
pressure.
Testing Pressure: 196 kPa (2 kg/cm
2/28.45 psi)
Radiator Cap Inspection
The radiator filler cap is designed to maintain coolant
pressure in the cooling system at 103 kPa (1.05
kg/cm
2/15 psi).
Check the radiator filler cap with a radiator filler cap
tester.The radiator filler cap must be replaced if it fails to hold
the specified pressure during the test procedure.
Radiator Filler Cap Pressure Valve: 88.2 – 117.6 kPa
(0.899 – 1.199 kg/cm
2/12.8 – 17.1 psi)
Negative Valve (Reference): 1.0 – 3.9 kPa
(0.01 – 0.04 kg/cm
2/0.14 – 0.57 psi)
Thermostat Operating Test
1. Completely submerge the thermostat in water.
2. Heat the water.
Stir the water constantly to avoid direct heat being
applied to the thermostat.
3. Check the thermostat initial opening temperature.
Thermostat Initial Opening Temperature:
83 – 87°C (181 – 189°F)
4. Check the thermostat full opening temperature.
Thermostat Full Opening Temperature:
100°C (212°F)
Valve Lift at Fully Open Position: 9.5 mm (0.374
in)0
-10
-20
-30
-40
-50
-60
10 20 30
Mixing ratio (%)
Freezing point (
C)
40 50 60
111RW002
110RS005
110RS006
031RS003

6E–5 4JX1–TC ENGINE DRIVEABILITY AND EMISSIONS
Conditions for Clearing the MIL/DTC 6E–159. . . . .
Diagnostic Aids 6E–159. . . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P1562
(Flash DTC 35) System Voltage Too Low
at Cranking 6E–160. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Circuit Description 6E–160. . . . . . . . . . . . . . . . . . . . .
Action Taken When the DTC Sets 6E–160. . . . . . .
Conditions for Clearing the MIL/DTC 6E–160. . . . .
Diagnostic Aids 6E–160. . . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P1587
(Flash DTC 25) Brake SW Malfunction 6E–161. . . .
Circuit Description 6E–161. . . . . . . . . . . . . . . . . . . . .
Action Taken When the DTC Sets 6E–161. . . . . . .
Conditions for Clearing the MIL/DTC 6E–161. . . . .
Diagnostic Aids 6E–161. . . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P1588
(Flash DTC 25) Brake SW Malfunction 6E–163. . . .
Circuit Description 6E–163. . . . . . . . . . . . . . . . . . . . .
Action Taken When the DTC Sets 6E–163. . . . . . .
Conditions for Clearing the MIL/DTC 6E–163. . . . .
Diagnostic Aids 6E–163. . . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0601
(Flash DTC 55) ECM Checksum Error 6E–165. . . . .
Action Taken When the DTC Sets 6E–165. . . . . . .
Conditions for Clearing the MIL/DTC 6E–165. . . . .
Diagnostic Aids 6E–165. . . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0650
(Flash DTC 77) Check Engine Lam Circuit
Open/Short 6E–166. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Circuit Description 6E–166. . . . . . . . . . . . . . . . . . . . .
Action Taken When the DTC Sets 6E–166. . . . . . .
Conditions for Clearing the MIL/DTC 6E–166. . . . .
Diagnostic Aids 6E–166. . . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0654
(Flash DTC 27) Tachometer Circuit
Open/Short 6E–168. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Circuit Description 6E–168. . . . . . . . . . . . . . . . . . . . .
Action Taken When the DTC Sets 6E–168. . . . . . .
Conditions for Clearing the MIL/DTC 6E–168. . . . .
Diagnostic Aids 6E–168. . . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P1655
(Flash DTC 17) Thermo Relay Circuit
Open/Short 6E–170. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Circuit Description 6E–170. . . . . . . . . . . . . . . . . . . . .
Action Taken When the DTC Sets 6E–170. . . . . . .
Conditions for Clearing the MIL/DTC 6E–170. . . . .
Diagnostic Aids 6E–170. . . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P1657
(Flash DTC 76) ECM Main Relay Circuit
Open/Short 6E–172. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Circuit Description 6E–172. . . . . . . . . . . . . . . . . . . . .
Action Taken When the DTC Sets 6E–172. . . . . . .
Conditions for Clearing the MIL/DTC 6E–172. . . . .
Diagnostic Aids 6E–172. . . . . . . . . . . . . . . . . . . . . . . . Diagnostic Trouble Code (DTC) P1589
(Flash DTC 47) Transmission SW Circuit
Open/Short 6E–174. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Circuit Description 6E–174. . . . . . . . . . . . . . . . . . . . .
Action Taken When the DTC Sets 6E–174. . . . . . .
Conditions for Clearing the MIL/DTC 6E–174. . . . .
Diagnostic Aids 6E–174. . . . . . . . . . . . . . . . . . . . . . . .
Symptom Diagnosis 6E–176. . . . . . . . . . . . . . . . . . . . .
Default Matrix Table 6E–199. . . . . . . . . . . . . . . . . . . . .
On–Vehicle Service Camshaft Position
(CMP) Sensor 6E–201. . . . . . . . . . . . . . . . . . . . . . . . . .
Removal Procedure 6E–201. . . . . . . . . . . . . . . . . . . .
Inspection Procedure 6E–201. . . . . . . . . . . . . . . . . .
Installation Procedure 6E–201. . . . . . . . . . . . . . . . . .
Crankshaft Position (CKP) Sensor 6E–202. . . . . . . . .
Removal Procedure 6E–202. . . . . . . . . . . . . . . . . . . .
Installation Procedure 6E–202. . . . . . . . . . . . . . . . . .
Engine Coolant Temperature (ECT) Sensor 6E–203.
Removal Procedure 6E–203. . . . . . . . . . . . . . . . . . . .
Installation Procedure 6E–203. . . . . . . . . . . . . . . . . .
Intake Air Temperature (IAT) Sensor 6E–203. . . . . . .
Removal Procedure 6E–203. . . . . . . . . . . . . . . . . . . .
Installation Procedure 6E–204. . . . . . . . . . . . . . . . . .
Manifold Absolute Pressure (MAP) Sensor 6E–204.
Removal Procedure 6E–204. . . . . . . . . . . . . . . . . . . .
Installation Procedure 6E–205. . . . . . . . . . . . . . . . . .
Oil Temperature (OT) Sensor 6E–205. . . . . . . . . . . . .
Removal Procedure 6E–205. . . . . . . . . . . . . . . . . . . .
Installation Procedure 6E–206. . . . . . . . . . . . . . . . . .
Malfunction Indicator Lamp (MIL) 6E–206. . . . . . . . . .
Removal and Installation Procedure 6E–206. . . . . .
Engine Control Module (ECM) 6E–206. . . . . . . . . . . .
Service Precaution 6E–206. . . . . . . . . . . . . . . . . . . .
Electrostatic Discharge (ESD) Damage 6E–206. . .
Removal Procedure 6E–207. . . . . . . . . . . . . . . . . . . .
Installation Procedure 6E–208. . . . . . . . . . . . . . . . . .
EEPROM 6E–208. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General Description 6E–208. . . . . . . . . . . . . . . . . . . .
Functional Check 6E–208. . . . . . . . . . . . . . . . . . . . . .
Intake Throttle Position (ITP) Sensor 6E–208. . . . . . .
Removal Procedure 6E–208. . . . . . . . . . . . . . . . . . . .
Function Check 6E–209. . . . . . . . . . . . . . . . . . . . . . .
Installation Procedure 6E–209. . . . . . . . . . . . . . . . . .
Vehicle Speed Sensor (VSS) 6E–210. . . . . . . . . . . . .
Removal Procedure 6E–210. . . . . . . . . . . . . . . . . . . .
Inspection Procedure 6E–210. . . . . . . . . . . . . . . . . .
Installation Procedure 6E–210. . . . . . . . . . . . . . . . . .
Air Cleaner/Air Filter 6E–211. . . . . . . . . . . . . . . . . . . . .
Removal Procedure 6E–211. . . . . . . . . . . . . . . . . . . .
Installation Procedure 6E–211. . . . . . . . . . . . . . . . . .
Accel Position (AP) Sensor 6E–211. . . . . . . . . . . . . . .
Removal Procedure 6E–211. . . . . . . . . . . . . . . . . . . .
Installation Procedure 6E–212. . . . . . . . . . . . . . . . . .
Accelerator Pedal Replacement 6E–212. . . . . . . . . . .

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–20
4JX1–TC ENGINE DRIVEABILITY AND EMISSIONS
NumberNameLocation
20Rail Pressure Control ValveIn the High Pressure Oil Pump
21Fuel PumpIn the High Pressure Oil Pump
22EVRVOn the Intake Manifold
23MAP (Manifold Absolute Pressure) SensorOn the Intake Manifold
24EGR ValveOn the Intake Manifold
25Air CleanerAt the left Engine Room
26ECMBehind the Air Cleaner

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–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