2003 DAEWOO MATIZ coolant temperature

ENGINE COOLING 1D–15
DAEWOO M-150 BL2
D102D517
ENGINE COOLANT TEMPERATURE
SENSOR
Removal Procedure
1. Disconnect the negative battery cable.
2. Disconnect the lower radiator hose and drain the
coolant “Draining and Refilling the Cooling System” in
this section.
3. Remove the engine coolant temperature (ECT) sen-
sor.
Disconnect the electrical connector (1).
Remove the ECT sensor (2).
D12D518A
20 Nm
Installation Procedure
1. Install the ECT sensor.
Tighten
Tighten the ECT sensor to 20 Nm (15 lb-ft).
Connect the electrical connector to the ECT sen-
sor (1).
2. Connect the lower radiator hose and refill the coolant.
Refer to “Draining and Refilling the Cooling System”
in this section.
3. Connect the negative battery cable.
D102B533
COOLANT PUMP
Removal Procedure
1. Disconnect the negative battery cable.
2. Disconnect the lower radiator hose and drain the
coolant. Refer to “Draining and Refilling the Cooling
System” in this section.
3. Remove the timing belt. Refer to Section 1B, Engine
Mechanical.
4. Remove the rear timing belt cover.
Remove the bolts (1).
Remove the rear timing belt cover (2).
D102D519
5. Remove the coolant pump.
Remove the nuts (1).
Remove the bolts (2).
Remove the coolant pump (3).
Remove the gasket.
Notice: Remove the coolant pump as shown figure (a).

ENGINE COOLING 1D–17
DAEWOO M-150 BL2
SPECIFICATIONS
GENERAL SPECIFICATIONS
ApplicationDescriptionUnitStandardLimit
Cooling
SystemCooling Type–Forced Water
Circulation
CoolantCoolant CapacityL/qt3.8/4.00
Thermostat Type–Pellet Type
Temperature(opened initially)°C(°F)82(180)
ThermostatTemperature(perfectly opened)°C(°F)95(203.4)
Temperature(perfectly closed)°C(°F)80(176.4)
Stroke(perfectly opened)mm(in.)8 (0.32)
Cooling Fan Type–Electric
Blade NumberEA6
Cooling Fan Diametermm(inch)300(11.8)
Electric CoolingTemperature At Low Speed ON°C(°F)93(199.8)Fan
Temperature At Low Speed OFF°C(°F)90(194.4)
Temperature At High Speed ON°C(°F)100(212.4)
Temperature At High Speed OFF°C(°F)97(207)
Surge TankOpen Pressure of The Pressure ValvekPa (psi)120–150
(17.4–21.8)
Surge Tank
Open Pressure of The Vacuum ValvekPa (psi)10 (1.5)
Water Pump Type–Centrifugal
Coolant PumpImpeller Diametermm(in.)60(2.36)
Impeller Blade NumberEA7
Radiator Type–Cross–Flow
Core Widthmm(in.)458(18.03)RadiatorCore Heightmm(in.)295(11.61)
Core Depth (Standard/Heavy Duty)mm(in.)16/27(0.63/1.06)
Resistance
(Coolant Temperature 50°C(122.4°F))Ω185.2
Coolant
TemperatureResistance
(Coolant Temperature 85°C(185.4°F))Ω49.2
SensorResistance
(Coolant Temperature 105°C(221.4°F))Ω27.5
Engine CoolantResistance
(Coolant Temperature 20°C(68.4°F))Ω3,520
Temperature
SensorResistance
(Coolant Temperature 80°C(176.4°F))Ω332

1D–18 ENGINE COOLING
DAEWOO M-150 BL2
FASTENER TIGHTENING SPECIFICATIONS
ApplicationNmLb-FtLb-In
Engine Coolant Temperature Sensor10–89
Coolant Temperature Sensor2015–
Coolant Pipe Bolt8 – 15–71 – 130
Electric Cooling Fan Motor Nut3.0 – 3.2–27 – 28
Electric Cooling Fan Assembly Bolt3.5 – 4.5–31 – 40
Distributor Case Bolt/Nut8 – 12–71 – 106
Radiator Mounting Bracket Bolt3.5 – 4.5–31 – 40
Thermostat Housing Bolt8 – 15–71 – 130
Water Inlet Cap Bolt8 – 12–71 – 106
Coolant Pump Bolt/Nut9–12–80 – 106
Coolant Pump Stud Bolt9–12–80 – 106

DAEWOO M-150 BL2
SECTION 1F
ENGINE CONTROLS
CAUTION: Disconnect the negative battery cable before removing or installing any electrical unit or when a
tool or equipment could easily come in contact with exposed electrical terminals. Disconnecting this cable
will help prevent personal injury and damage to the vehicle. The ignition must also be in LOCK unless
otherwise noted.
TABLE OF CONTENTS
Description and Operation 1F-4. . . . . . . . . . . . . . . . . .
Ignition System Operation 1F-4. . . . . . . . . . . . . . . . . .
Electronic Ignition System Ignition Coil 1F-4. . . . . . .
Crankshaft Position Sensor 1F-4. . . . . . . . . . . . . . . . .
Camshaft Position Sensor 1F-4. . . . . . . . . . . . . . . . . .
Idle Air System Operation 1F-4. . . . . . . . . . . . . . . . . .
Fuel Control System Operation 1F-4. . . . . . . . . . . . . .
Evaporative Emission Control System
Operation 1F-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Controlled Charcoal Canister 1F-5. . . . . . . . . . . . . . . .
Positive Crankcase Ventilation Control System
Operation 1F-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine Coolant Temperature Sensor 1F-6. . . . . . . . .
Throttle Position Sensor 1F-6. . . . . . . . . . . . . . . . . . . .
Catalyst Monitor Oxygen Sensors 1F-6. . . . . . . . . . .
Electric Exhaust Gas Recirculation Valve 1F-6. . . . .
Intake Air Temperature Sensor 1F-7. . . . . . . . . . . . . .
Idle Air Control Valve 1F-7. . . . . . . . . . . . . . . . . . . . . .
Manifold Absolute Pressure Sensor 1F-7. . . . . . . . . .
Engine Control Module 1F-8. . . . . . . . . . . . . . . . . . . . .
Fuel Injector 1F-8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuel Cutoff Switch (Inertia Switch) 1F-8. . . . . . . . . . .
Knock Sensor 1F-8. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Variable Reluctance (VR) Sensor 1F-8. . . . . . . . . . . .
Octane Number Connector 1F-8. . . . . . . . . . . . . . . . .
Strategy-Based Diagnostics 1F-9. . . . . . . . . . . . . . . .
EOBD Serviceability Issues 1F-9. . . . . . . . . . . . . . . . .
Serial Data Communications 1F-10. . . . . . . . . . . . . . .
Euro On-Board Diagnostic (EOBD) 1F-10. . . . . . . . .
Comprehensive Component Monitor Diagnostic
Operation 1F-11. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Common EOBD Terms 1F-11. . . . . . . . . . . . . . . . . . . .
DTC Types 1F-13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reading Diagnostic Trouble Codes 1F-13. . . . . . . . .
Primary System-Based Diagnostics 1F-15. . . . . . . . Diagnostic Information and Procedures 1F-17. . . .
System Diagnosis 1F-17. . . . . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Aids 1F-17. . . . . . . . . . . . . . . . . . . . . . . . . .
Idle Learn Procedure 1F-17. . . . . . . . . . . . . . . . . . . . .
Euro On-Board Diagnostic (EOBD) System
Check 1F-18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ECM Output Diagnosis 1F-20. . . . . . . . . . . . . . . . . . . .
Multiple ECM Information Sensor DTCs Set 1F-21. .
Engine Cranks But Will Not Run 1F-25. . . . . . . . . . . .
No Malfunction Indicator Lamp 1F-30. . . . . . . . . . . . .
Malfunction Indicator Lamp On Steady 1F-32. . . . . .
Fuel System Diagnosis 1F-34. . . . . . . . . . . . . . . . . . . .
Fuel Pump Relay Circuit Check 1F-36. . . . . . . . . . . .
Main Relay Circuit Check 1F-38. . . . . . . . . . . . . . . . . .
Manifold Absolute Pressure Check 1F-40. . . . . . . . . .
Idle Air Control System Check 1F-42. . . . . . . . . . . . .
Ignition System Check 1F-45. . . . . . . . . . . . . . . . . . . .
Engine Cooling Fan Circuit Check 1F-48. . . . . . . . . .
Data Link Connector Diagnosis 1F-52. . . . . . . . . . . . .
Fuel Injector Balance Test 1F-54. . . . . . . . . . . . . . . . .
Diagnostic Trouble Code Diagnosis 1F-55. . . . . . . .
Clearing Trouble Codes 1F-55. . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Codes 1F-55. . . . . . . . . . . . . . . . .
DTC P0107 Manifold Absolute Pressure Sensor
Low Voltage 1F-58. . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0108 Manifold Pressure Sensor High
Voltage 1F-62. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0112 Intake Air Temperature Sensor Low
Voltage 1F-66. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0113 Intake Air Temperature Sensor High
Voltage 1F-68. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0117 Engine Coolant Temperature Sensor
Low Voltage 1F-72. . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0118 Engine Coolant Temperature Sensor
High Voltage 1F-74. . . . . . . . . . . . . . . . . . . . . . . . . . .

ENGINE CONTROLS 1F–3
DAEWOO M-150 BL2
DTC P1628 Immobilizer No Successful
Communication 1F-270. . . . . . . . . . . . . . . . . . . . . . .
DTC P1629 Immovilizer Wrong Computation 1F-272
DTC P0656 Fuel Level Gauge Circuit Fault 1F-274.
DTC P1660 Malfunction Indicator Lamp (MIL)
High Voltage 1F-276. . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P1661 Malfunction Indicator Lamp (MIL)
Low Voltage 1F-278. . . . . . . . . . . . . . . . . . . . . . . . . .
Symptom Diagnosis 1F-280. . . . . . . . . . . . . . . . . . . . . .
Important Preliminary Checks 1F-280. . . . . . . . . . . . .
Intermittent 1F-281. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Hard Start 1F-283. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Surges or Chuggles 1F-286. . . . . . . . . . . . . . . . . . . . .
Lack of Power, Sluggishness or Sponginess 1F-288
Detonation/Spark Knock 1F-290. . . . . . . . . . . . . . . . . .
Hesitation, Sag, Stumble 1F-292. . . . . . . . . . . . . . . . .
Cuts Out, Misses 1F-294. . . . . . . . . . . . . . . . . . . . . . . .
Poor Fuel Economy 1F-296. . . . . . . . . . . . . . . . . . . . . .
Rough, Unstable, or Incorrect Idle, Stalling 1F-297. .
Excessive Exhaust Emissions or Odors 1F-300. . . .
Dieseling, Run-on 1F-302. . . . . . . . . . . . . . . . . . . . . . .
Backfire 1F-303. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Maintenance and Repair 1F-304. . . . . . . . . . . . . . . . . .
On-Vehicle Service 1F–304 . . . . . . . . . . . . . . . . . . . . . . .
Fuel Pump 1F–304 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuel Pressure Regulator 1F-305. . . . . . . . . . . . . . . . .
Fuel Filter 1F-306. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuel Tank 1F-307. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuel Rail and Injectors 1F-308. . . . . . . . . . . . . . . . . . .
Evaporator Emission Canister 1F-309. . . . . . . . . . . . . Evaporator Emission Canister Purge
Solenoid 1F-310. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Manifold Absolute Pressure (MAP) Sensor 1F-310. .
Throttle Body 1F-311. . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine Coolant Temperature (ECT) Sensor 1F-312.
Intake Air Temperature (ECT) Sensor 1F-313. . . . . .
Oxygen Sensor (O2S 1) 1F-314. . . . . . . . . . . . . . . . . .
Heated Oxygen Sensor (HO2S 2) 1F-314. . . . . . . . .
Electric Exhaust Gas Recirculation (EEGR)
Valve 1F-315. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Knock Sensor 1F-315. . . . . . . . . . . . . . . . . . . . . . . . . . .
Electronic Ignition (EI) System Ignition Coil 1F-316.
Crankshaft Position (CKP) Sensor 1F-316. . . . . . . .
Camshaft Position (CMP) Sensor 1F-317. . . . . . . . . .
Engine Control Module (ECM) 1F-317. . . . . . . . . . . . .
Specifications 1F-319. . . . . . . . . . . . . . . . . . . . . . . . . . .
Fastener Tightening Specification 1F-319. . . . . . . . . .
Special Tools 1F-319. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Special Tools Table 1F-319. . . . . . . . . . . . . . . . . . . . . .
Schematic and Routing Diagrams 1F-320. . . . . . . . .
ECM Wiring Diagram
(Sirius D3 – 1 of 5) 1F-320. . . . . . . . . . . . . . . . . . . .
ECM Wiring Diagram
(Sirius D3 – 2 of 5) 1F-321. . . . . . . . . . . . . . . . . . . .
ECM Wiring Diagram
(Sirius D3 – 3 of 5) 1F-322. . . . . . . . . . . . . . . . . . . .
ECM Wiring Diagram
(Sirius D3 – 4 of 5) 1F-323. . . . . . . . . . . . . . . . . . . .
ECM Wiring Diagram
(Sirius D3 – 5 of 5) 1F-324. . . . . . . . . . . . . . . . . . . .

1F–4 ENGINE CONTROLS
DAEWOO M-150 BL2
DESCRIPTION AND OPERATION
IGNITION SYSTEM OPERATION
This ignition system does not use a conventional distrib-
utor and coil. It uses a crankshaft position sensor input
to the Engine Control Module (ECM). The ECM then de-
termines Electronic Spark Timing (EST) and triggers the
electronic ignition system ignition coil.
This type of distributorless ignition system uses a “waste
spark’’ method of spark distribution. Each cylinder is in-
dividural with coil per cylinder.
These systems use the EST signal from the ECM to
control the EST. The ECM uses the following informa-
tion:

Engine load (manifold pressure or vacuum).

Atmospheric (barometric) pressure.

Engine temperature.

Intake air temperature.

Crankshaft position.

Engine speed (rpm).
ELECTRONIC IGNITION SYSTEM
IGNITION COIL
The Electronic Ignition (EI) system ignition coil is
mounted near on the cylinder head.
A terminals of the EI system ignition coil provides the
spark for each spark plug. The EI system ignition coil is
not serviceable and must be replaced as an assembly.
CRANKSHAFT POSITION SENSOR
This Electronic Ignition (EI) system uses a magnetic
crankshaft position sensor. This sensor protrudes
through its mount to within approximately 1.3 mm (0.05
inch) of the crankshaft reluctor. The reluctor is a special
wheel attached to the crankshaft with 58 slots machined
into it, 57 of which are equally spaced in 6-degree inter-
vals. The last slot is wider and serves to generate a
“sync pulse.” As the crankshaft rotates, the slots in the
reluctor change the magnetic field of the sensor, creat-
ing an induced voltage pulse. The longer pulse of the
58th slot identifies a specific orientation of the crank-
shaft and allows the Engine Control Module (ECM) to
determine the crankshaft orientation at all times. The
ECM uses this information to generate timed ignition
and injection pulses that it sends to the ignition coils and
to the fuel injectors.
CAMSHAFT POSITION SENSOR
The Camshaft Position (CMP) sensor sends a CMP sig-
nal to the Engine Control Module (ECM). The ECM uses
this signal as a “sync pulse” to trigger the injectors in the
proper sequence. The ECM uses the CMP signal to indi-
cate the position of the #1 piston during its power stroke.
This allows the ECM to calculate true sequential fuel in-jection mode of operation. If the ECM detects an incor-
rect CMP signal while the engine is running, Diagnostic
Trouble Code (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 en-
gine can be restarted. It will run in the calculated se-
quential mode with a 1-in-6 chance of the injector
sequence being correct.
IDLE AIR SYSTEM OPERATION
The idle air system operation is controlled by the base
idle setting of the throttle body and the Idle Air Control
(IAC) valve.
The Engine Control Module (ECM) uses the IAC valve to
set the idle speed dependent on conditions. The ECM
uses information from various inputs, such as coolant
temperature, manifold vacuum, etc., for the effective
control of the idle speed.
FUEL CONTROL SYSTEM
OPERATION
The function of the fuel metering system is to deliver the
correct amount of fuel to the engine under all operating
conditions. The fuel is delivered to the engine by the in-
dividual fuel injectors mounted into the intake manifold
near each cylinder.
The main fuel control sensors are the Manifold Absolute
Pressure (MAP) sensor, the oxygen sensor (O2S), and
the heated oxygen sensor (HO2S).
The MAP sensor measures or senses the intake man-
ifold vacuum. Under high fuel demands, the MAP sensor
reads a low vacuum condition, such as wide open
throttle. The Engine Control Module (ECM) uses this in-
formation to enrich the mixture, thus increasing the fuel
injector on-time, to provide the correct amount of fuel.
When decelerating, the vacuum increases. This vacuum
change is sensed by the MAP sensor and read by the
ECM, which then decreases the fuel injector on-time
due to the low fuel demand conditions.
The O2S is located in the exhaust manifold. The HO2S
is located in the exhaust pipe. The oxygen sensors indi-
cate to the ECM the amount of oxygen in the exhaust
gas, and the ECM changes the air/fuel ratio to the en-
gine by controlling the fuel injectors. The best air/fuel ra-
tio to minimize exhaust emissions is 14.7:1, which
allows the catalytic converter to operate most efficiently.
Because of the constant measuring and adjusting of the
air/fuel ratio, the fuel injection system is called a “closed
loop” system.
The ECM uses voltage inputs from several sensors to
determine how much fuel to provide to the engine. The

ENGINE CONTROLS 1F–5
DAEWOO M-150 BL2
fuel is delivered under one of several conditions, called
“modes.’’
Starting Mode
When the ignition is turned ON, the ECM turns the fuel
pump relay on for 2 seconds. The fuel pump then builds
fuel pressure. The ECM also checks the Engine Coolant
Temperature (ECT) sensor and the Throttle Position
(TP) sensor and determines the proper air/fuel ratio for
starting the engine. The ECM controls the amount of
fuel delivered in the starting mode by changing how long
the fuel injector is turned on and off. This is done by
“pulsing’’ the fuel injectors for very short times.
Run Mode
The run mode has two conditions called “open loop’’ and
“closed loop.’’
Open Loop
When the engine is first started and it is above 400 rpm,
the system goes into “open loop’’ operation. In “open
loop,’’ the ECM ignores the signal from the O2S and cal-
culates the air/fuel ratio based on inputs from the ECT
sensor and the MAP sensor. The ECM stays in ”open
loop” until the following conditions are met:

The O2S has a varying voltage output, showing that it
is hot enough to operate properly.

The ECT sensor is above a specified temperature.

A specific amount of time has elapsed after starting
the engine.
Closed Loop
The specific values for the above conditions vary with
different engines and are stored in the Electronically
Erasable Programmable Read-Only Memory (EE-
PROM). When these conditions are met, the system
goes into “closed loop” operation. In “closed loop,” the
ECM calculates the air/fuel ratio (fuel injector on-time)
based on the signals from the oxygen sensors. This al-
lows the air/fuel ratio to stay very close to 14.7 to 1.
Acceleration Mode
The ECM responds to rapid changes in throttle position
and airflow and provides extra fuel.
Deceleration Mode
The ECM responds to changes in throttle position and
airflow and reduces the amount of fuel. When decelera-
tion is very fast, the ECM can cut off fuel completely for
short periods of time.
Battery Voltage Correction Mode
When battery voltage is low, the ECM can compensate
for a weak spark delivered by the ignition module by us-
ing the following methods:

Increasing the fuel injector pulse width.

Increasing the idle speed rpm.

Increasing the ignition dwell time.
Fuel Cut-Off Mode
No fuel is delivered by the fuel injectors when the ignition
is off. This prevents dieseling or engine run-on. Also, the
fuel is not delivered if there are no reference pulses re-
ceived from the CKP sensor. This prevents flooding.
EVAPORATIVE EMISSION CONTROL
SYSTEM OPERATION
The basic Evaporative Emission (EVAP) control system
used is the charcoal canister storage method. This
method transfers fuel vapor from the fuel tank to an acti-
vated carbon (charcoal) storage canister which holds
the vapors when the vehicle is not operating. When the
engine is running, the fuel vapor is purged from the car-
bon element by intake airflow and consumed in the nor-
mal combustion process.
Gasoline vapors from the fuel tank flow into the tube la-
beled TANK. These vapors are absorbed into the car-
bon. The canister is purged by Engine Control Module
(ECM) when the engine has been running for a specified
amount of time. Air is drawn into the canister and mixed
with the vapor. This mixture is then drawn into the intake
manifold.
The ECM supplies a ground to energize the controlled
charcoal canister purge solenoid valve. This valve is
Pulse Width Modulated (PWM) or turned on and off sev-
eral times a second. The controlled charcoal canister
purge PWM duty cycle varies according to operating
conditions determined by mass airflow, fuel trim, and in-
take air temperature.
Poor idle, stalling, and poor driveability can be caused
by the following conditions:

An inoperative controlled canister purge valve.

A damaged canister.

Hoses that are split, cracked, or not connected to the
proper tubes.
CONTROLLED CHARCOAL
CANISTER
The controlled charcoal canister is an emission control
device containing activated charcoal granules. The con-
trolled charcoal canister is used to store fuel vapors from
the fuel tank. Once certain conditions are met, the En-
gine Control Module (ECM) activates the controlled
charcoal canister purge solenoid, allowing the fuel va-
pors to be drawn into the engine cylinders and burned.
POSITIVE CRANKCASE
VENTILATION CONTROL SYSTEM
OPERATION
A Positive Crankcase Ventilation (PCV) control system
is used to provide complete use of the crankcase va-

1F–6 ENGINE CONTROLS
DAEWOO M-150 BL2
pors. Fresh air from the air cleaner is supplied to the
crankcase. The fresh air is mixed with blowby gases
which then pass through a vacuum hose into the intake
manifold.
Periodically inspect the hoses and the clamps. Replace
any crankcase ventilation components as required.
A restricted or plugged PCV hose may cause the follow-
ing conditions:

Rough idle

Stalling or low idle speed

Oil leaks

Oil in the air cleaner

Sludge in the engine
A leaking PCV hose may cause the following conditions:

Rough idle

Stalling

High idle speed
ENGINE COOLANT TEMPERATURE
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
(100,000 ohms at –40C [–40F]) while high tempera-
ture causes low resistance (70 ohms at 130C [266F]).
The Engine Control Module (ECM) supplies 5 volts to
the ECT sensor through a resistor in the ECM and mea-
sures the change in voltage. The voltage will be high
when the engine is cold and low when the engine is hot.
By measuring the change in voltage, the ECM can de-
termine the coolant temperature. The engine coolant
temperature affects most of the systems that the ECM
controls. A failure in the ECT sensor circuit should set a
Diagnostic Trouble Code (DTC) P0117 or P0118. Re-
member, these DTC indicate a failure in the ECT circuit,
so proper use of the chart will lead either to repairing a
wiring problem or to replacing the sensor to repair a
problem properly.
THROTTLE POSITION SENSOR
The Throttle Position (TP) sensor is a potentiometer
connected to the throttle shaft of the throttle body. The
TP sensor electrical circuit consists of a 5-volt supply
line and a ground line, both provided by the Engine Con-
trol Module (ECM). The ECM calculates the throttle
position by monitoring the voltage on this signal line. The
TP sensor output changes as the accelerator pedal is
moved, changing the throttle valve angle. At a closed
throttle position, the output of the TP sensor is low,
about 0.4–0.8 volt. As the throttle valve opens, the out-
put increases so that, at Wide Open Throttle (WOT), the
output voltage will be about 4.5–5 volts.The ECM can determine fuel delivery based on throttle
valve angle (driver demand). A broken or loose TP sen-
sor can cause intermittent bursts of fuel from the injector
and an unstable idle, because the ECM thinks the
throttle is moving. A problem in any of the TP sensor cir-
cuits should set a Diagnostic Trouble Code (DTC)
P0122 or P0123. Once the DTC is set, the ECM will sub-
stitute a default value for the TP sensor and some ve-
hicle performance will return.
CATALYST MONITOR OXYGEN
SENSORS
Three-way catalytic converters are used to control emis-
sions of hydrocarbons (HC), carbon monoxide (CO),
and oxides of nitrogen (NOx). The catalyst within the
converters promotes a chemical reaction. This reaction
oxidizes the HC and CO present in the exhaust gas and
converts them into harmless water vapor and carbon
dioxide. The catalyst also reduces NOx by converting it
to nitrogen. The ECM can monitor this process using the
oxygen sensor (O2S) and heated oxygen sensor
(HO2S). These sensors produce an output signal which
indicates the amount of oxygen present in the exhaust
gas entering and leaving the three-way converter. This
indicates the catalyst’s ability to efficiently convert ex-
haust gasses. If the catalyst is operating efficiently, the
O2S signals will be more active than the signals pro-
duced by the HO2S. The catalyst monitor sensors oper-
ate the same way as the fuel control sensors. The
sensors’ main function is catalyst monitoring, but they
also have a limited role in fuel control. If a sensor output
indicates a voltage either above or below the 450 mV
bias voltage for an extended period of time, the Engine
Control Module (ECM) will make a slight adjustment to
fuel trim to ensure that fuel delivery is correct for catalyst
monitoring.
A problem with the O2S circuit will set DTC P0131,
P0132, P0133 or P0134 depending on the special condi-
tion. A problem with the HO2S signal will set DTC
P0137, P0138, P0140 or P0141 depending on the spe-
cial condition.
A fault in the heated oxygen sensor (HO2S) heater ele-
ment or its ignition feed or ground will result in lower oxy-
gen sensor response. This may cause incorrect catalyst
monitor diagnostic results.
ELECTRIC EXHAUST GAS
RECIRCULATION VALVE
The Electric Exhaust Gas Recirculation (EEGR) system
is used on engines equipped with an automatic trans-
axle to lower oxides of nitrogen (NOx) emission levels
caused by high combustion temperature. The main ele-
ment of the system is the EEGR valve, controlled electri-
cally by the Engine Control Module (ECM). The EEGR
valve feeds small amounts of exhaust gas into the intake