coolant temperature OPEL FRONTERA 1998 Workshop Manual

6E–251 ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P1508 IAC System Low RPM
T321115
Circuit Description
The powertrain control module (PCM) controls engine
idle speed by adjusting the position of the idle air control
(IAC) motor pintle. The IAC is a bi-directional stepper
motor driven by two coils. The PCM applies current to the
IAC coils in steps (counts) to extend the IAC pintle into a
passage in the throttle body to decrease air flow. The
PCM reverses the current to retract the pintle, increasing
air flow. This method allows highly accurate control of idle
speed and quick response to changes in engine load. If
the PCM detects a condition where too low of an idle
speed is present and the PCM is unable to adjust idle
speed by increasing the IAC counts, DTC P1508 will set,
indicating a problem with the idle control system.
Conditions for Setting the DTC
No Tech 2 test is being run.
None of these DTCs are set: TP sensor, VSS, ECT,
EGR, fuel system, MAF, MAP, IAT, canister purge,
injector control or ignition control.
Barometric pressure is above 75 kPa.
Engine coolant temperature (ECT) is above 50C
(120
F).
Engine speed is more than 100-200 RPM lower than
desired idle, based upon coolant temperature.
The engine has been running for at least 125 seconds.
Vehicle speed is less than 1 mph.
Canister purge duty cycle is above 10%.
Ignition voltage is between 9.5 volts and 16.7 volts.
The throttle is closed.
Engine speed is lower than desired idle.
All of the above conditions are met for 10 seconds.
Action Taken When the DTC Sets
The PCM will illuminate the malfunction indicator lamp
(MIL) after the second consecutive trip in which the
fault is detected.
The PCM 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 P1508 can be cleared by using the Tech 2 “Clear
Info” function or by disconnecting the PCM battery
feed.
Diagnostic Aids
Check for the following conditions:
Poor connection at PCM or IAC motor – 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 for damage.
Restricted air intake system – Check for a possible
collapsed air intake duct, restricted air filter element,
or foreign objects blocking the air intake system.
Throttle body – Check for objects blocking the IAC
passage or throttle bore, excessive deposits in the IAC

6E–254
ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P1509 IAC System High RPM
T321115
Circuit Description
The powertrain control module (PCM) controls engine
idle speed by adjusting the position of the idle air control
(IAC) motor pintle. The IAC is a bi-directional stepper
motor driven by two coils. The PCM applies current to the
IAC coils in steps (counts) to extend the IAC pintle into a
passage in the throttle body to decrease air flow. The
PCM reverses the current to retract the pintle, increasing
air flow. This method allows highly accurate control of idle
speed and quick response to changes in engine load. If
the PCM detect a condition where too high of an idle
speed is present and the PCM is unable to adjust idle
speed by increasing the IAC counts, DTC P1509 will set,
indicating a problem with the idle control system.
Conditions for Setting the DTC
No Tech 2 test is being run.
None of these DTCs are set: TP sensor, VSS, ECT,
EGR, fuel system, MAF, MAP, IAT, canister purge,
injector control or ignition control.
Barometric pressure is above 75 kPa.
Engine coolant temperature is above 50C (120F).
Engine speed is more than 100-200 RPM lower than
desired idle, based upon coolant temperature.
The engine has been running for at least 125 seconds.
Vehicle speed is less than 1 mph.
Canister purge duty cycle is above 10%.
Ignition voltage is between 9.5 volts and 16.7 volts.
Engine speed is lower than desired idle.
All of the above conditions are met for 5 seconds.
Action Taken When the DTC Sets
The PCM will illuminate the malfunction indicator lamp
(MIL) after the second consecutive trip in which the
fault is detected.
The PCM 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 P1509 can be cleared by using the Tech 2 “Clear
Info” function or by disconnecting the PCM battery
feed.
Diagnostic Aids
Check for the following conditions:
Poor connection at PCM or IAC motor – 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 for damage.
Vacuum leak – Check for a condition that causes a
vacuum leak, such as disconnected or damaged
h o s e s , l e a k s a t t h e E G R v a l v e a n d t h e E G R p i p e t o t h e
intake manifold, leaks at the throttle body, faulty or
incorrectly installed PCV valve, leaks at the intake
manifold, etc.

6E–263 ENGINE DRIVEABILITY AND EMISSIONS
Hard Start Symptom
StepActionVa l u e ( s )Ye sNo
1DEFINITION: Engine cranks, but does not start
for a long time. Does eventually run, or may start
but immediately stalls.
Was the “On-Board Diagnostic (OBD) System Check”
performed?
—Go to Step 2
Go to OBD
System
Check
21. Perform a bulletin search.
2. If a bulletin that addresses the symptom is found,
correct the condition as instructed in the bulletin.
Was a bulletin found that addresses the symptom?
—Verify repairGo to Step 3
3Was a visual/physical check performed?
—Go to Step 4
Go to
Visual/Physic
al Check
4Check engine coolant temperature (ECT) sensor for
shift in value. After 8 hours with the hood up and the
engine not running, connect Tech 2. With the ignition
“ON” and the engine not running, compare engine
coolant temperature to intake air temperature.
Are ECT and IAT within the specified value of each
other?
5C ( 9F)Go to Step 8Go to Step 5
51. Using Tech 2, display the engine coolant
temperature and note the value.
2. Check the resistance of the engine coolant
temperature sensor.
3. Refer to
Engine Coolant Temperature Sensor
Temperature vs. Resistance
chart on DTC P0118
Diagnostic Support
for resistance specifications.
Is the resistance value near the resistance for the
temperature noted?
—Go to Step 7Go to Step 6
6Replace the ECT sensor.
Is the action complete?
—Verify repair—
7Locate and repair high resistance or poor connection in
the ECT signal circuit or the ECT sensor ground.
Is the action complete?
—Verify repair—
81. Check for a faulty, plugged, or incorrectly installed
PCV valve.
2. If a problem is found, repair as necessary.
Was a problem found?
—Verify repairGo to Step 9
91. Check for water- or alcohol-contaminated fuel.
2. If a problem is found, repair as necessary.
Was a problem found?
—Verify repairGo to Step 10
101. Perform the procedure in Fuel System Pressure
Te s t
.
2. If a problem is found, repair as necessary.
Was a problem found?
—Verify repairGo to Step 11
111. Check for proper ignition voltage output with spark
tester J 26792 (ST-125). Refer to
Electric Ignition
System
for procedure.
2. If a problem is found, repair as necessary.
Was a problem found?
—Verify repairGo to Step 12

6E–292
ENGINE DRIVEABILITY AND EMISSIONS
Crankshaft Position (CKP)
Sensor
Removal Procedure
1. Disconnect the negative battery cable.
2. Disconnect the electrical connector to the CKP
sensor.
3. Remove one bolt and the CKP sensor from the right
side of the engine block, just behind the mount.
NOTE: Use caution to avoid any hot oil that might drip
out.
TS22909
Inspection Procedure
1. Inspect the sensor O-ring for cracks or leaks.
2. Replace the O-ring if it is worn or damaged.
3. Lubricate the new O-ring with engine oil.
4. Install the lubricated O-ring.
Installation Procedure
1. Install the CKP sensor in the engine block.
2. Install the CKP sensor mounting bolt.
Tighten
Tighten the mounting bolt to 9 Nꞏm (78 lb in.).
TS22909
3. Connect the electrical connector to the CKP sensor.
4. Connect the negative battery cable.
Engine Coolant Temperature
(ECT) Sensor
Removal Procedure
NOTE: Care must be taken when handling the engine
coolant temperature (ECT) sensor. Damage to the ECT
sensor will affect proper operation of the fuel injection
system.
1. Disconnect the negative battery cable.
2. Drain the radiator coolant. Refer to
Draining and
Refilling Cooling System
in Engine Cooling.
3. Disconnect the electrical connector.
014RW127

6E–323 ENGINE DRIVEABILITY AND EMISSIONS
11. Connect the fuel filler fuse at the tank.
12. Connect the air breather hose at the tank.
TS23796
13. Fill the fuel tank with fuel.
14. Tighten the fuel filler cap.
15. Connect the negative battery cable.
Throttle Body (TB)
Removal Procedure
1. Disconnect the negative battery cable.
2. Drain the cooling system. Refer to
Cooling System.
3. Remove the accelerator cable assembly. Refer to
Accelerator Cable in Engine Speed Control System..
4. Disconnect the electrical connectors:
Throttle position (TP) sensor.
Idle air control (IAC) solenoid.
Intake air temperature (IAT) sensor. Refer to
Intake Air Temperature Sensor.
035RW023
5. Disconnect the vacuum hose below the air horn.
6. Remove the intake air duct clamp.
7. Disconnect the intake air duct.
8. Disconnect the coolant lines from the throttle body.
9. Remove the bolts from the common chamber.
10. Remove the throttle body from the common chamber.
11. Remove the gasket from the upper intake manifold.
035RW024
12. Remove the IAC. Refer to Idle Air Control (IAC)
Solenoid
.
13. Remove the TP sensor. Refer to
Throttle Position
(TP) Sensor
.
Inspection Procedure
NOTE: Do not use solvent of any type when you clean the
gasket surfaces on the intake manifold and the throttle
body assembly. The gasket surfaces and the throttle
body assembly may be damaged as a result.
If the throttle body gasket needs to be replaced,
remove any gasket material that may be stuck to the
mating surfaces of the manifold.
Do not leave any scratches in the aluminum casting.
Installation Procedure
1. Install the TP sensor. Refer to Throttle Position (TP)
Sensor
.
2. Install the IAC. Refer to
Idle Air Control (IAC)
Solenoid
.
3. Install the gasket on the common chamber.
4. Install the throttle body on the common chamber.

6E–324
ENGINE DRIVEABILITY AND EMISSIONS
5. Secure the gasket and the throttle body with the four
bolts.
The vacuum lines must be properly routed under
the throttle body before tightening the mounting
bolts.
Tighten
Tighten the throttle body mounting bolts to 24 Nꞏm
(17 lb ft.).
035RW024
6. Install the coolant lines.
7. Connect all the vacuum lines.
8. Install the intake air duct.
9. Tighten the intake air duct clamp.
10. Connect all the electrical connectors:
Throttle position (TP) sensor.
Idle air control (IAC) solenoid.
Intake air temperature (IAT) sensor. Refer to
Intake Air Temperature Sensor.
035RW023
11. Install the accelerator cable assembly. Refer to
Accelerator Cable in Engine Speed Control System..
12. Fill the cooling system. Refer to
Cooling System.
13. Install the negative battery cable.
Electronic Ignition System
Removal Procedure
1. Disconnect the negative battery cable.
2. Disconnect the electrical connector at the ignition coil.
3. Remove the two screws that secure the ignition coil to
the rocker cover.
014RW108
4. Remove the ignition coil and the spark plug boot from
the spark plug.
Twist the ignition coil while pulling it straight up.
014RW091
5. Use the spark plug socket in order to remove the
spark plug from the engine.

6E–334
ENGINE DRIVEABILITY AND EMISSIONS
Removal Procedure
S o m e c o n n e c t o r s u s e t e r m i n a l s c a l l e d M e t r i - P a c k S e r i e s
150. These may be used at the engine coolant
temperature (ECT) sensor.
1. Slide the seal (1) back on the wire.
2. Insert the J 35689 tool or equivalent (3) in order to
release the terminal locking tang (2).
060
3. Push the wire and the terminal out through the
connector. If you reuse the terminal, reshape the
locking tang.
Installation Procedure
Metri-Pack terminals are also referred to as “pull-to-seat”
terminals.
1. In order to install a terminal on a wire, the wire must be
inserted through the seal (2) and through the
connector (3).
2. The terminal (1) is then crimped onto the wire.
061
3. Then the terminal is pulled back into the connector to
seat it in place.

6E–335 ENGINE DRIVEABILITY AND EMISSIONS
General Description
General Description (PCM and
Sensors)
58X Reference PCM Input
The powertrain control module (PCM) uses this signal
from the crankshaft position (CKP) sensor to calculate
engine RPM and crankshaft position at all engine speeds.
The PCM also uses the pulses on this circuit to initiate
injector pulses. If the PCM receives no pulses on this
circuit, DTC P0337 will set. The engine will not start and
run without using the 58X reference signal.
A/C Request Signal
This signal tells the PCM when the A/C mode is selected
at the A/C control head. The PCM uses this to adjust the
idle speed before turning “ON” the A/C clutch. The A/C
compressor will be inoperative if this signal is not
available to the PCM.
Refer to
A/C Clutch Circuit Diagnosis for A/C wiring
diagrams and diagnosis for the A/C electrical system.
Crankshaft Position (CKP) Sensor
The crankshaft position (CKP) sensor provides a signal
used by the powertrain control module (PCM) to calculate
the ignition sequence. The CKP sensor initiates the 58X
reference pulses which the PCM uses to calculate RPM
and crankshaft position.
Refer to
Electronic Ignition System for additional
information.
0013
Camshaft Position (CMP) Sensor and
Signal
The camshaft position (CMP) sensor sends a CMP signal
t o t h e P C M . T h e P C M u s e s t h i s s i g n a l a s a “ s y n c p u l s e ” t otrigger the injectors in the proper sequence. The PCM
uses the CMP signal to indicate the position of the #1
piston during its power stroke. This allows the PCM to
calculate true sequential fuel injection (SFI) mode of
operation. If the PCM detects an incorrect CMP signal
while the engine is running, DTC P0341 will set. If the
CMP signal is lost while the engine is running, the fuel
injection system will shift to a calculated sequential fuel
injection mode based on the last fuel injection pulse, and
the engine will continue to run. As long as the fault is
present, the engine can be restarted. It will run in the
calculated sequential mode with a 1-in-6 chance of the
injector sequence being correct.
Refer to
DTC P0341 for further information.
0014
Engine Coolant Temperature (ECT) Sensor
The engine coolant temperature (ECT) sensor is a
thermistor (a resistor which changes value based on
temperature) mounted in the engine coolant stream. Low
coolant temperature produces a high resistance of
100,000 ohms at –40
C (–40F). High temperature
causes a low resistance of 70 ohms at 130
C (266F).
The PCM supplies a 5-volt signal to the ECT sensor
through resistors in the PCM and measures the voltage.
The signal voltage will be high when the engine is cold and
low when the engine is hot. By measuring the voltage, the
PCM calculates the engine coolant temperature. Engine
coolant temperature affects most of the systems that the
PCM controls.
Tech 2 displays engine coolant temperature in degrees.
After engine start-up, the temperature should rise steadily
to about 85
C (185F). It then stabilizes when the
thermostat opens. If the engine has not been run for
several hours (overnight), the engine coolant
temperature and intake air temperature displays should
be close to each other. A hard fault in the engine coolant
sensor circuit will set DTC P0177 or DTC P0118. An
intermittent fault will set a DTC P1114 or P1115.

6E–336
ENGINE DRIVEABILITY AND EMISSIONS
0016
Electrically Erasable Programmable Read
Only Memory (EEPROM)
The electrically erasable programmable read only
memory (EEPROM) is a permanent memory chip that is
physically soldered within the PCM. The EEPROM
contains the program and the calibration information that
the PCM needs to control powertrain operation.
Unlike the PROM used in past applications, the EEPROM
is not replaceable. If the PCM is replaced, the new PCM
will need to be programmed. Equipment containing the
correct program and calibration for the vehicle is required
to program the PCM.
Fuel Control Heated Oxygen Sensors
The fuel control heated oxygen sensors (Bank 1 HO2S 1
and Bank 2 HO2S 1) are mounted in the exhaust stream
where they can monitor the oxygen content of the exhaust
gas. The oxygen present in the exhaust gas reacts with
the sensor to produce a voltage output. This voltage
should constantly fluctuate from approximately 100 mV to
900 mV. The heated oxygen sensor voltage can be
monitored with Tech 2. By monitoring the voltage output
of the oxygen sensor, the PCM calculates the pulse width
command for the injectors to produce the proper
combustion chamber mixture.
Low HO2S voltage is a lean mixture which will result in
a rich command to compensate.
High HO2S voltage is a rich mixture which will result in
a lean command to compensate.
An open Bank 1 HO2S 1 signal circuit will set a DTC
P0134 and Tech 2 will display a constant voltage between
400-500 mV. A constant voltage below 300 mV in the
sensor circuit (circuit grounded) will set DTC P0131. A
constant voltage above 800 mV in the circuit will set DTC
P0132. Faults in the Bank 2 HO2S 1 signal circuit will
cause DTC 0154 (open circuit), DTC P0151 (grounded
circuit), or DTC P0152 (signal voltage high) to set.
0012
Intake Air Temperature (IAT) Sensor
The intake air temperature (IAT) sensor is a thermistor
which changes its resistance based on the temperature of
air entering the engine. Low temperature produces a high
resistance of 100,000 ohms at –40
C (–40F). High
temperature causes low resistance of 70 ohms at 130
C
(266
F) . The PCM supplies a 5-volt signal to the sensor
through a resistor in the PCM and monitors the signal
voltage. The voltage will be high when the incoming air is
cold. The voltage will be low when the incoming air is hot.
By measuring the voltage, the PCM calculates the
incoming air temperature. The IAT sensor signal is used
to adjust spark timing according to the incoming air
density.
Tech 2 displays the temperature of the air entering the
engine. The temperature should read close to the
ambient air temperature when the engine is cold and rise
as underhood temperature increases. If the engine has
not been run for several hours (overnight), the IAT sensor
temperature and engine coolant temperature should read
close to each other. A fault in the IAT sensor circuit will set
DTC P0112 or DTC P0113.

6E–337 ENGINE DRIVEABILITY AND EMISSIONS
0018
Knock Sensor
Insufficient gasoline octane levels may cause detonation
in some engines. Detonation is an uncontrolled explosion
(burn) in the combustion chamber. This uncontrolled
explosion results from a flame front opposite that of the
normal flame front produced by the spark plug. The
rattling sound normally associated with detonation is the
result of two or more opposing pressures (flame fronts)
colliding within the combustion chamber. Light
detonation is sometimes considered normal, but heavy
detonation could result in engine damage.
A knock sensor system is used to control detonation. This
system is designed to retard spark timing up to 20
degrees to reduce detonation in the engine. This allows
the engine to use maximum spark advance to improve
driveability and fuel economy.
The knock sensor system has two major components:
The knock sensor (KS) module.
The knock sensor.
The knock sensor, mounted in the engine block near the
cylinders, detects abnormal vibration in the engine. The
sensor produces an AC output signal of about 10
millivolts. The signal amplitude and frequency are
dependent on the amount of knock being experienced.
The signal voltage increases with the severity of the
knock. This signal voltage is input to the PCM. The PCM
then retards the ignition control (IC) spark timing based
on the KS signal being received.
The PCM determines whether knock is occurring by
comparing the signal level on the KS circuit with the
voltage level on the noise channel. The noise channel
allows the PCM to reject any false knock signal by
indicating the amount of normal engine mechanical noise
present. Normal engine noise varies depending on the
engine speed and load. If the voltage level on the KS
noise channel circuit is below the range considered
normal, DTC P0327 will set, indicating a fault in the KScircuit or the knock sensor. If the PCM determines that an
abnormal minimum or maximum noise level is being
experienced, DTC P0325 will set.
The PCM contains a knock sensor (KS) module. The KS
module contains the circuitry which allows the PCM to
utilize the KS signal and diagnose the KS sensor and the
KS circuitry. If the KS module is missing or faulty, a
continuous knock condition will be indicated, and the
PCM will set DTC P0325.
Although it is a plug-in device, the KS module is not
replaceable. If the KS module is faulty, the entire PCM
must be replaced.
0009
Linear Exhaust Gas Recirculation (EGR)
Control
The PCM monitors the exhaust gas recirculation (EGR)
actual position and adjusts the pintle position accordingly.
The PCM uses information from the following sensors to
control the pintle position:
Engine coolant temperature (ECT) sensor.
Throttle position (TP) sensor.
Mass air flow (MAF) sensor.
Mass Air Flow (MAF) Sensor
The mass air flow (MAF) sensor measures the difference
between the volume and the quantity of air that enters the
engine. “Volume” means the size of the space to be filled.
“Quantity” means the number of air molecules that will fit
into the space. This information is important to the PCM
because heavier, denser air will hold more fuel than
lighter, thinner air. The PCM adjusts the air/fuel ratio as
needed depending on the MAF value. Tech 2 reads the
MAF value and displays it in terms of grams per second
(gm/s). At idle, Tech 2 should read between 4-7 gm/s on a
fully warmed up engine. Values should change quickly on
acceleration. Values should remain stable at any given