1988 PONTIAC FIERO Service Repair Manual

6E-8 DRIVEABILITY AND EMISSIONS - FUEL INJECTION
Throttle Position Sensor (TPO) Coolant Q~erature
Values read will be the voltage as seen by the Engine
temperature is displayed in Celsius
ECM. The voltage should be the TPS specification degrees.
After the engine is started, temperature
with the throttle closed and go up to about 5 volts should
rise steadily to about
85-95" C, then stabilize
with throttle wide open
(WOT). when the thermostat opens.
Throttle Angle
Displayed, in percent, is the amount the throttle is
open. 0% is closed throttle, 100% is wide open throttle.
Oxygen (Of) Sensor
The reading will be read out in millivolts (mv)
with a range from 1 to 999 mv. If the reading is
consistently below 350 (350 mv), the fuel system
is
running lean as seen by the ECM; and if the reading is
consistently above 550 (550 mv), the system is
running rich.
In this position, information is used for assembly
verification only. PROM ID is useful only when the
vehicle
is equipped with the original ECM and PROM
or Mem-Cal.
Reading displays engine rpm. It is often useful if
extra reference pulses are suspected. A sudden high
rpm indication while at a steady throttle would
indicate electrical interference
(EMI) in the reference
circuit. This interference
is usually caused by ECM
wires too close to ignition secondary wires or an open
distributor ground circuit.
Displayed is vehicle speed, useful in checking TCC
application speed or speedometer accuracy.
MAF
This displays the amount of air passing the Mass
Air Flow
(MAF) sensor, in grams per second. It is
useful when comparing the airflow between a problem
vehicle and a known good one. Normal readings at
idle are about
4 to 8 grams. If a MAF code is set, this
reading will display the ECM default value.
This display should be the same as MAF when
there are no failures in the MAP sensor circuit. When
an MAF code is set, however, this value will not
change, and will indicate the
grn/sec that the failure
has detected.
Manifold Air Temperature (MAT) Sensor
This displays temperature of the intake manifold
air. It should read close to ambient air temperature
when the engine is cold, and rise as underhood and
engine temperatures increase.
Manifold Absolute Pressure (MAP)
The MAP sensor produces a low signal voltage
when manifold pressure is low (high vacuum) and a
high voltage when the pressure is high (low vacuum).
With the ignition "ON" and the engine stopped,
I
the manifold pressure is equal to atmospheric
pressure, and the signal voltage will be high. This 1
information is used by the ECM as an indication of
vehicle altitude and is referred to as BARO.
Comparison of this
BARO reading with a known good
vehicle with the same sensor is a good way to check
accuracy of a "suspect" sensor
*. Readings should be
the same
+ .4 volt. I
* A MAP sensor has a colored plastic insert visible I I
in the connector cavity. Sensors with the same insert I
color are identical in calibration. The harness I
I
electrical connector color also should be the same as 1 the sensor insert color.
I Vacuum (Differential Pressure) Sensor
The vacuum sensor produces a low signal voltage
when manifold vacuum is low, and a high voltage
when the vacuum is high.
With the ignition "ON" and the engine stopped,
there is no vacuum, so the voltage is low (under
1
volt). With the engine idling the vacuum is high so the
voltage is high (over
3 volts).
A vacuum sensor has a colored plastic insert
visible in the connector cavity. Sensors with the same
insert color are identical in calibration. The harness
electrical connector color also should be the same as
the sensor insert color.
This displays barometric pressure. The ECM uses
this information to adjust for altitude and pressure.
This value will vary depending on barometric
pressure and altitude. Some vehicles use a dedicated
bar0 sensor, while others take a MAP reading before
the engine is started, and at various times during
engine operation.

DRIVEABILITY AND EMISSIONS - FUEL INJECTION 6E-9
ParWNelatral Switch IAC (Idle Air Control)
The indication in this mode may vary with This system is used to control engine idle speed to
manufacturer so the type of reading for a particular the desired rpm, for different operating conditions. In
tool should be checked in the operator's manual. The this mode, the numbers will indicate the position to
important thing is that the the reading changes state which
the ECM has moved the valve pintle. The ECM
(switches) when the gear selector is moved from moves
the IAC in counts, or steps, and the number of
paridneutral to drive or reverse. these counts are displayed on a "Scan" tool.
"Trque Convertor Clutch (TCC)
In this position, the tool will indicate when the
TCC has been commanded by the ECM to turn "ONJ'.
This does not necessarily mean that the clutch was
engaged but only that the
ECM grounded the circuit
internally. The best way to determine if the clutch has
engaged is to monitor engine rpm when the TCC
comes "ON".
EGR (Duty Cycle)
The EGR system uses a valve to feed a small
amount of exhaust gas back into the intake manifold
to control formation of NO,. Like all ECM outputs, the
"Scan" tool only indicates that the ECM has
commanded the function, and does not indicate that
the function has really happened.
EGR Position
This indicates the position of the EGR pintle.
Integrator and Block Learn
Normal readings for these positions are around
128. If higher, it indicates that the ECM is adding fuel
to the base fuel calculation because the system is lean,
and if the numbers are below 128, the ECM is taking
out fuel from the base calculation because the system
is rich. The integrator gives short term corrective
action, while the block learn portion (which is a long
term correction) will only change if the integrator has
seen a condition which lasts for a calibrated period of
time.
Block Learn Multiplier (BLM) Cell - or -
Block Learn Memory (BLM)
There are up to sixteen different cells,
corresponding to ranges of rpm and engine load
(indicated by MAF or MAP signals), and other
conditions, such as
A/C or P/N switch "ON" or "OFF",
etc. The ECM learns how much adjustment is needed
in each cell, and retains it in memory, so that the
adjustment will immediately be made when the
engine operates in that cell (or
rpmlload range). This
parameter will display what cell the ECM is currently
using for the fuel calculation.
Desired RPM
This indicates the rpm to which the ECM is trying
to control the idle.
Shift Light
This displays "yes" when the ECM is commanding
the shift light to turn "ON".
PPSW (Pump Prime Switch)
This is the voltage on the fuel pump feed circuit.
The ECM will adjust fuel injector base pulse width
from this voltage value rather than from battery
voltage.
NC Request
The state of the A/C signal line to the ECM is
shown. It should read "yes" whenever the
IVC is
requested.
NC Clutch
"ON" is displayed when the ECM has commanded
the
A/C clutch "ON".
Knock Retard
This indicates the number of degrees the ECM is
retarding the electronic spark timing (EST).
Knock Signal
This displays a "yes" when knock is detected by
the ECM, and a "no" when knock is not detected.
Battery Voltage
This displays the battery voltage detected at the
ECM ignition input.
Fan
"ON" is displayed when the cooling fan has been
commanded "ON".

6E-18 DRIVEABILITY AND EMISSIONS - FUEL INJECRON
CCP (Carbon Canister Purge)
This displays "ON" when the canister purge
solenoid is commanding purge. Some display duty
cycle from
0-1008.
2nd Gear
This displays the state of the 2nd gear switch.
Yes=2nd gear applied. It remains applied in 3rd and
4th gears.
3rd Gear
This displays the state of the 3rd gear switch.
Yes= 3rd gear applied. It remains applied in 4th gear.
4th Gear
This displays the state of the 4th gear switch.
Yes
= 4th gear applied.
Fan Request
State of the AJC fan control switch is displayed. It
should read "yes" when fan is requested. Some
engines may display the state of the 2nd fan, if used.
Power Steering Pressure Switch
This reading displays the state of switch, and may
vary with the tool used, and the type of switch
installed on the vehicle. The important thing is that
the reading changes state (switches) when the
steering is moved against the stops.
Electronic Control Module (ECM)
This section describes the ECM and the
information sensors in the system. Figure
4 shows
the operating conditions which the ECM may sense
and the systems that the ECM may control. (See
specific engines to determine which are applicable
to
that engine.)
Fuel Control System
The ECM controls the aidfuel delivery to the
combustion chamber by controlling the fuel flow
through the
injector(s).
Electric Fuel Pump (In-tank)
The in-tank fuel pump is controlled by the ECM.
When ignition is turned "ON", the pump will run for 2
seconds, then stop unless the ECM is receiving
ignition pulses, as when cranking or running.
Evaporative Emission ControI
This system has a canister which stores fuel vapor
from the fuel tank. The fuel vapor is removed from the
canister and consumed in the normal combustion
process when the engine is running. This system is
used on all engines and may or may not be controlled
by the ECM.
ilectronic Spark Timing (EST)
This system is controlled by the ECM, which
controls spark advance (timing), and is used on all
engines.
SECTION B - DRIVEABILIW SYMPTOMS Electronic Spark
Control (ESC)
Always start with Section "A" "Diagnostic Circuit
Check" before proceeding to the driveability
symptoms or an emissions test failure. Section "A"
checks the ECM, which may cause the driveability
problem. A definition of each symptom is included.
This will then lead to the most probable causes of the
driveability problem.
SECTION C - COMPONENT SYSTEMS
There are many component systems that are used
to control fuel and emissions. Section
"C" introduces
each component system or control with a general
description, diagnosis, and on-vehicle service.
Each of the Section "C" diagnosis sections contain
information on how the "ScanJ' tool can be used for
diagnosing a particular component when a trouble
code has not been set. (example: Section
"Cl" under
diagnosis will explain how the "Scan" tool can be used
for diagnosis as well as what the normal readings
would be for the
ECM sensors.) This
system uses a knock sensor in connection
with the ECM to control spark timing, to allow the
engine to have maximum spark advance without
spark knock. This improves driveability and fuel
economy, but will retard spark
if detonation (spark
knock) is detected.
Air Injection Reaction (A.I.R.)
The system provides additional oxygen to the
exhaust gases to continue the combustion process.
The system also supplies additional air to the catalytic
converter under certain conditions. The A.I.R. system
is not on all engines.
Early Fuel Evaporation (EFE)
The EFE system heats the engine induction
system electrically or with exhaust gas during cold

DRIVEABILITY AND EMISSIONS - FUEL INJEC"F0N 6E-11
@ A/% "On" or "Off" r Air Management
r Engine Coolant Temwrature r Canister Purge
@ Engine crank signal r Exhaust Gas Recirculation (EGR)
@ Exhaust Oxygen(02) Sensor @ Electronic Spark Timing (EST)
r Distributor Reference @ Fuel Control
@ Crankshaft Position @ Idle Air Control (lAC)
@ Engine Speed (RPM) Transmission Converter Clutch (TCC)
Manifold Absolute Pressure (MAP)
@ Park Neutral Switch (PB) Position @ Electric Fuel Pump
r System Voltage Air Conditioning
r Throttle Position (TPS) @ Engine Cooling Fan
r Transmission Gear Position
r Vehicle Speed (VSS) @ "Service Engine Soon" Light
@ Fuel Pump Voltage @ Diagnostic Terminal (ALDL)
r Power Steering Pressure @ Data Output (ALDL)
Mass Air Flow (MAF) @ Electronic Spark Control (ESC)
@ Manifold Air Temperature (MAT) @ Early Fuel Evaporation (EFE)
r EGR Vacuum @ Idle Speed (ISC, ILC,)
@ Engine Knock (ESC)
r Differential Pressure (VAC) 6-1-87
*7S
3429- 6E
Figure
4 - ECM Operating Conditions Sensed and Systems Controlled
driveaway. This system is not used on all engines and Electric Cooling Fan Control
may or may not be controlled by the ECM.
Under certain conditions, the
ECM may control
Exhaust Gas Recirculation (ECR) the electric cooling fan to cool the engine and A/C
condenser. At cruising speed, the ECM may turn the
The
EGR system uses a valve to feed a small fan
off for better fuel economy. This control is on
amount of exhaust gas back into the intake manifold transverse
engine front wheel drive vehicles.
to control formation of
NO,.
Positive Crankcase Ventilation (PCV) or
Transmission Converter
Clutch (TCC) Crankcase Ventilation (CV)
The TCC is ECM controlled and is used on all
engines with an automatic transmission. This system
reduces slippage losses in the torque converter by
coupling the engine flywheel to the output shaft of the
transmission.
Shift Light Control
The ECM controls the shift light on some manual
transmission vehicles to indicate the best shift point
for maximum fuel economy. This control is not on all
applications.
NC Clutch Control
The ECM may control the AJC clutch on the
compressor to improve idle quality. This control is not
on all engines. The
PCV or CV system passes crankcase vapors
into the intake manifold. This system is not controlled
by the
ECM and is used on all engines.
Thermostatic Air Cleaner (THERMAC)
The THERMAC system regulates heated air
through the air cleaner to provide uniform inlet air
temperature, which gives good driveability under
various climatic conditions. This system is not
controlled by the
ECM.
ABBREVIATIONS AND GLOSSARY OF TERMS
Abbreviations used in this section are listed below
in alphabetical order with an explanation of the
abbreviation. There are some variations in the use of
periods and in capitalization (as mph,
m.p.h., Mph,

6E-12 DRIVEABILITY AND EMISSIONS - FUEL INJECUION
and MPH) for abbreviations used in this Section, but
all types are acceptable.
NA/F - AI WFUEL (NF RATIO)
A.I.R.
- AIR INJECTOR REACTION SYSTEM - Air
flow from pump is directed into engine exhaust
manifold
and/or converter to reduce exhaust
emissions.
ALDL - ASSEMBLY LINE DIAGNOSTIC LINK - Used
at assembly to evaluate Computer Command Control,
and for service to flash the "Service Engine Soon"
light
if there are trouble codes. It also is used by
"Scan" tools to obtain ECM serial data.
BARO - BAROMETRIC ABSOLUTE PRESSURE
SENSOR
- Reads atmospheric pressure.
B + - Battery Positive Terminal (12 Volts) or
system voltage with the engine running
(approximately 13.8
v.)
CALPAK - A device used with fuel injection to
allow fuel delivery in the event of a PROM or ECM
malfunction.
CALIBRATOR - (PROM) - An electronic component
that can be
specifically programmed to meet engine
operating requirements for a
specific vehicle model.
It plugs into the Engine Control Module
(ECM).
CCC - COMPUTER COMMAND CONTROL - has an
electronic control module to control airlfuel and
emission systems.
CLCC - CLOSED LOOP CARBURETOR CONTROL -
Used to describe oxygen sensor to ECM to MIC
solenoid circuit operation.
C3I - Computer Controlled Coil Ignition. Produces
the ignition spark without the aid of an ignition
distributor.
CCP - CONTROLLED CANISTER PURGE - ECM
controlled solenoid valve that permits manifold
vacuum to purge the evaporative emissions from the
charcoal canister.
CID - CUBIC INCH DISPLACEMENT - Used to
describe engine size.
UL OR ULOOP - "CLOSED LOOP" - Describes ECM
fuel control when using oxygen sensor information.
COOLANT TEMPERATURE SENSOR - Device that
senses the engine coolant temperature, and passes
that information to the engine control module.
CONV. - CATALYTIC CONVERTER, THREE-WAY -
EXHAUST CONVERTER. Containing platinum and
palladium to speed up conversion of
HC and CO, and
rhodium to accelerate conversion of NO,.
CO - CARBON MONOXIDE - One of the pollutants
found in engine exhaust.
6V - CRANKCASE VENTlhaflON - Prevents fumes
in crankcase from passing into the atmosphere, by
drawing them into the intake manifold and burning
them in the the combustion process.
DIAGNOSTIC CODE - Pair of numbers obtained
from flashing "Service Engine Soon" light or
displaying on a "Scan" tool. This code can be used to
determine the system malfunction.
DIAGNOSTIC TERM. - Lead of ALDL Connector
which is grounded to get a Trouble Code.
It is
grounded with the engine running to enter the "Field
Service Mode".
DIS - Direct Ignition System. Produces the
ignition spark without the aid of an ignition
distributor.
DVM (10 Meg.) - Digital Voltmeter with 10 Million
ohms resistance
- used for measurement in electronic
systems.
DWELL - The amount of time (recorded on a dwell
meter in degrees of crankshaft rotation) that current
passes through a closed switch; for example, ignition
contact points or internal switch in an electronic
control module.
EAC - ELECTRIC AIR CONTROL - Used on A.I.R.
system to direct air flow to air switching valve or to
atmosphere.
EAS - ELECTRIC AIR SWITCHING - used to direct air
flow to catalytic converter or exhaust ports of the
engine.
ECM - ENGINE CONTROL MODULE (ELECTRONIC) -
A metal case (located in passenger compartment)
containing electronic circuitry which electrically
controls and monitors airlfuel and emission systems
on computer command control, and turns
"ON" the
"Service Engine Soon" light when a malfunction
occurs in the system.
EFI - ELECTRONIC FUEL INJECTION - Computer
Command Control using throttle body fuel injection.
EGR - EXHAUST GAP REClRCUbATlON - Method of
reducing NO, emission levels by causing exhaust gas
to be added to airlfuel mixture in combustion
chamber, thus cooling combustion.
EECS - EVAPORATIVE EMISSIONS CONTROL
SYSTEM
- Used to prevent gasoline vapors in the fuel
tank from entering the atmosphere.
EFE - EARLY FUEL EVAPORATION - Method of
warming the intake manifold during cold engine
operation. Provides efficient airlfuel mixing.
ENERGIZEIDE-ENERGIZE - When current is passed
through a coil (energized) such as the canister purge
solenoid, the plunger is pulled into the solenoid.

DRIVEABILIW AND EMISSIONS - FUEL INJECTION 6E-13
When the voltage to the solenoid is turned off, (de-
energized), a spring raises the plunger.
ESC - ELECTRONIC SPARK CONTROL - Used to
sense detonation and retard spark advance when
detonation occurs.
EST - ELECTRONIC SPARK TIMING - ECM
controlled timing of ignition spark.
EVRV - ELECTRONIC VACUUM REGULAWR
VALVE - Controls EGR vacuum.
FED - FEDEWL - VehicleIEngine available in all
states except California.
GROUND - The negative (-) side of the battery.
Also could be a wire (conductor) shorted to ground.
HC - HYDROCARBONS - One of the pollutants
found in engine exhaust.
HIGH IMPEDANCE VOLTMETER - Mas high
opposition to the flow of electrical current.
Good for
reading circuits with low current flow, such as found
in electronic systems because it allows tests to be
made without affecting the circuit.
HE1 - HIGH ENERGY IGNITION - A distributor that
uses an electronic module and pick-up coil in place of
contact points.
Hg - MERCURY - A calibration material used as a
standard for vacuum measurement.
IAC - IDLE AIR CONTROL - A valve installed in the
throttle body of fuel injected systems and controlled by
the ECM to regulate idle speed.
IDEAL MIXWRE - The airlfuel ratio which provides
the best performance, while maintaining maximum
conversion of exhaust emissions. Typically it is
14.7:1.
ID1 - INTEGRATED DIRECT IGNITION - Produces the
ignition spark without the aid of an ignition
distributor or spark plug wires.
IDLE AIR BLEED VALVE - Controls the amount of
air let into the idle fuel mixture prior to the mixture
entering the carburetor idle system, when the
MIC
solenoid is energized.
ILC - IDLE LOAD COMPENSATOR - Device used to
control throttle angle during long deceleration, such
as coasting down a long grade; it extends at wide open
throttle position or to prevent engine stalls at idle.
INPUTS - Information from sources (such as
coolant temperature sensors, exhaust oxygen sensor,
etc.) to the ECM that indicate how the systems are
performing.
INTERMITTENT - Occurs now and then; not
continuously. In electrical circuits, refers to
occasional open, short, or ground.
I.P. - INSTRUMENT PANEL
ISC - IDLE SPEED CONTROL - Regulates throttle
valve position to control idle speed. Idle speed is
controlled by the ECM and is not adjustable.
KMIHR - KILOMEnR PER HOUR - A metric unit
measuring speed needed to travel distance of one
kilometer (1000 meters) in one hour.
L - LITER - A metric unit of capacity.
L4 - FOUR CYLINDER IN-LINE ENGINE
MAF - MASS AIR FLOW - Sensor which measures
the amount of air entering the engine.
MALFUNCTION - A problem that causes the
system to operate incorrectly. Typical malfunctions
are wiring harness opens or shorts, failed sensors or
circuit components.
MANIFOLD VACUUM SENSOR - Indicates vacuum
in the intake manifold by measuring the pressure in
intake manifold in relation to barometric pressure. It
is also called a differential pressure sensor because
it
measures the difference between the two pressures. It
puts out a voltage which is highest when the vacuum
is highest. The maximum voltage is between 4 and 5
volts.
MAP - MANIFOLD ABSOLUTE PRESSURE SENSOR -
Reads pressure changes in intake manifold with
reference to zero pressure. It puts out a voltage which
is highest when the pressure is highest. The
maximum voltage is between
4 and 5 volts.
MAT - Manifold Air Temperature Sensor.
Measures temperature of air in the intake manifold.
MIC - MIXTURE CONTROL
MEM-CAL
- MEMORY CALIBRATOR - Contains
specific calibrations to meet the requirements of a
specific engine.
MFI - MULTlPORT FUEL INJECnON - Individual
injectors for each cylinder are mounted in the intake
manifold. The injectors are fired in groups rather than
individually.
MIXTURE CONTROL (MIC) SOLENOID - Device,
installed in carburetor, to regulate the airlfuel ratio.
MODE - A particular state of operation.
MPH - MILES PER HOUR - A unit measuring speed
needed to travel distance of one mile (5280 feet) in one
hour.
N.C. - NORMALLY CLOSED - State of relay contacts
or solenoid plunger when no voltage is applied.
N-rn - NEWTON METER (Torque) - A metric unit
describing force.

6E-14 DRIVEABILITY AND EMISSIONS - FUEL INJECTION
N.O. - NORMALLY OPEN - State of relay contacts
or solenoid plunger when no voltage
is applied.
NOx - NITROGEN, OXIDES OF - One of the
pollutants found in engine exhaust.
O2 - OXYGEN (Sensor) - Monitors the oxygen
content of the exhaust system and generates a voltage
signal to the ECM.
OIL or OILOOP - OPEN LOOP - Describes ECM fuel
control without use of oxygen sensor information.
OUTPUT - Result of a function typically controlled
by the ECM.
OXYGEN SENSOR. EXHAUST - Device that detects
the amount of oxygen
(02) in the exhaust stream.
P.A.1.R - PULSE AIR INJECTION REACTOR system -
pulsed air directed into engine to reduce exhaust
emissions.
PCV - POSITIVE CRANKCASE VENTILATION -
Prevent fumes in crankcase from passing into
atmosphere.
PFI - PORT FUEL INJECTION
PIN
- PARWNEUTWL
PORT - EXHAUST OR INTAKE PORT
PROM
- PROGRAMABLE READ ONLY MEMORY-
an electronic term used to describe the engine
calibration unit
.
RPM - REVOLUTIONS PER MINUTE - A measure of
rotational speed.
RVB - REAR VACUUM BMKE - is used to control
choke operation during cold engine conditions.
SELF-DIAGNOSTIC CODE - The ECM can detect
malfunctions in the system.
If a malfunction occurs,
the ECM turns on the "Service Engine Soon" light.
A
diagnostic code can be obtained from the ECM
through the "Service Engine Soon" light, or by use of a
"Scan" tool. This code will indicate the area of the
malfunction.
SES - SERVICE ENGINE SOON LIGHT - Lights when
a malfunction occurs in Computer Command Control
system.
TACH - TACHOMETER
TBI
- THROTTLE BODY INJECTION (Unit) - is
controlled by the ECM to supply precise airlfuel
mixture into the intake manifold.
TCC - TWNSMISSION I TRANSAXLE CONVERTER
CLUTCH
- ECM controlled solenoid in transmission
which positively couples the transmission to the
engine.
THERMAC - THERMOSTATIC AIR CLEANER -
provides preheated air to intake manifold to provide
better driveability when engine
is cold.
TPS - THROnLE POSITION SENSOR - Device that
tells the ECM the throttle position.
TVS - THERMAL VACUUM SWITCH - Used to
control vacuum in relationship to engine temperature.
V - VOLT
V-6 - SIX CYLINDER ENGINE - Two banks of
cylinders, arranged in a
"V".
V-8 - EIGHT CYLINDER ENGINE - Two banks of
cylinders, arranged in a
"V".
VACUUM - Negative pressure; less than
atmospheric pressure.
VACUUM, MANIFOLD - Vacuum source in
manifold below throttle plate.
VACUUM, PORTED - A vacuum source above I (atmospheric side ) of closed throttle plate. , I
WAC SENSOR - Abbreviation for differential
pressure sensor which is a
vacuum sensor.
VIN - VEHICLE IDENTIFIUTION NUMBER. 1
VSS - VEHICLE SPEED SENSOR - Sensor which
sends vehicle speed information to the ECM.
WASTECATE - A means of controlling the amount
of boost available for a Turbo charged engine.
WOT- WIDE OPEN THROPTLE. I
WIRING HARNESS SERVICE I
The ECM wire harness electrically connects the
ECM to the various solenoids, switches, and sensors in
vehicle engine compartment. The ECM is located
inside the vehicle passenger compartment.
Most connectors in the engine compartment are
protected against moisture and dirt which could create
oxidation and deposits on the terminals. This
protection is important because of the very low voltage
and current levels found in the electronic system. The
connectors have a lock which secures the male and
female terminals together. A secondary lock holds the
seal and terminal into the connector.
GENERAL
Molded-on connectors (like Metri-Pack) require
complete replacement of the connector. This means
splicing a new connector assembly into the harness.