
Spark control systems are designed to ensure the air/fuel
mixture is ignited at the best possible moment to provide optimum
efficiency and power and cleaner emissions.
Ensure vacuum hoses to the distributor, carburetor, spark
delay valves, thermal vacuum switches, etc., are in place and routed
properly. On Computerized Engine Controls (CEC), check for presence of\
required sensors (O2, MAP, CTS, TPS, etc.). Ensure they have not been
tampered with or modified.
Check for visible modification or replacement of the feedback
carburetor, fuel injection unit or injector(s) with a non-feedback
carburetor or fuel injection system. Check for modified emission-
related components unacceptable for use on pollution-controlled
vehicles.
AIR INJECTION SYSTEM (AIS)
Air Pump Injection System (AP)
The air pump is a belt-driven vane type pump, mounted to
engine in combination with other accessories. The air pump itself
consists of the pump housing, an inner air cavity, a rotor and a vane
assembly. As the vanes turn in the housing, filtered air is drawn in
through the intake port and pushed out through the exhaust port. See
Fig. 13 .
Check for missing or disconnected belt, check valve(s),
diverter valve(s), air distribution manifolds, etc. Check air
injection system for proper hose routing.
Fig. 13: Typical Air Pump Injection System
Courtesy of General Motors Corp.
Pulsed Secondary Air Injection (PAIR) System
PAIR eliminates the need for an air pump and most of the
associated hardware. Most systems consists of air delivery pipe(s),
pulse valve(s) and check valve(s). The check valve prevents exhaust
gases from entering the air injection system. See Fig. 14.
Ensure required check valve(s), diverter valve(s), air
distribution manifolds, etc., are present. Check air injection system
for proper hose routing.

TROUBLE SHOOTING
NOTE: To trouble shoot mechanical engine components, see
appropriate table in TROUBLE SHOOTING article in GENERAL
INFORMATION.
REMOVAL & INSTALLATION
CAUTION: When battery is disconnected, vehicle computer and memory
systems may lose memory data. Driveability problems may exist
until computer systems have completed a relearn cycle. See
COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION
before disconnecting battery.
NOTE: For installation reference, label all electrical connectors,
vacuum hoses and fuel lines before removal. Also place mating
marks on engine hood and other major assemblies before
removal.
FUEL PRESSURE RELEASE
CAUTION: Fuel system is under pressure. Pressure must be released
before servicing fuel system components.
Gasoline
1) Disconnect negative battery cable. Loosen fuel tank cap to
release tank pressure. Press on filler tube flap to relieve any
additional tank pressure.
NOTE: Fuel filler tube has spring-loaded flap located below fuel
fill cap to serve as secondary seal if fuel fill cap is not
tightened. It is part of EVAP monitor system when vehicle is
equipped with leak detection pump (LDP). Vehicle may be
equipped with flap installed into fuel filler tube even if
vehicle is NOT equipped with LDP and EVAP monitor system.
2) Remove fuel pump relay from Power Distribution Center
(PDC). For location of relay, refer to label on underside of PDC
cover. Start and run engine until it stalls. Attempt restarting engine
until it will no longer run.
3) Unplug connector from an injector. Attach one end of a
jumper wire (18 gauge or smaller) with alligator clips to either
injector terminal. Connect other end of jumper wire to positive side
of battery. Connect one end of a second jumper wire to remaining
injector terminal.
WARNING: Powering an injector for more than a few seconds will
permanently damage injector.
4) Touch other end of second jumper wire to negative terminal
of battery for no more than a few seconds. Place a rag below fuel
line. Disconnect quick-connect fitting at fuel rail. See FUEL LINE
DISCONNECT FITTINGS. Return fuel pump relay to PDC.
Compressed Natural Gas Fuel Tube Purging (5.2L)
1) Close control valve (clockwise) on all fuel cylinders.
Open manual shutoff valve (open when handle is parallel to fuel
tubes).
2) Start and operate engine until it runs out of fuel.
Attempt 3 more engine starts. If check valve or fuel fill receptacle

CLUTCH PEDAL POSITION SWITCHES
COLD START INJECTORS
CONNECTORS
COOLANT
COOLANT RECOVERY TANKS
COOLING FAN MOTOR MODULES
COOLING FAN MOTOR RELAYS AND MODULES
COOLING FAN MOTOR RESISTORS
COOLING FAN MOTOR SENSORS AND SWITCHES
COOLING FAN MOTOR SWITCHES
COOLING FAN MOTORS
CRANKSHAFT POSITION SENSORS
DECEL VALVES
DEFLECTORS
DIP STICKS AND TUBES
DIP STICK TUBES
DISTRIBUTOR ADVANCES AND RETARDERS (MECHANICAL AND VACUUM)
DISTRIBUTOR BOOTS AND SHIELDS
DISTRIBUTOR CAPS
DISTRIBUTOR RETARDERS (MECHANICAL AND VACUUM)
DISTRIBUTOR ROTORS
DISTRIBUTOR SHIELDS
DISTRIBUTORS
EARLY FUEL EVAPORATION VALVES (HEAT RISER ASSEMBLIES)
EGR COOLERS
EGR EXHAUST MANIFOLD PASSAGES
EGR INTAKE AND EXHAUST MANIFOLD PASSAGES
EGR PLATES AND COOLERS
ELECTRONIC SPARK CONTROL MODULES
ELECTRONIC TRANSMISSION CONTROL DEVICES
ELECTRONIC TRANSMISSION FEEDBACK DEVICES
ENGINE COOLANT TEMPERATURE SENSORS
ENGINE COOLING SYSTEMS
ENGINE COVERS (OIL PAN, VALVE COVER, TIMING COVER)
ENGINE OIL
ENGINE OIL CANISTERS
ENGINE OIL COOLERS (EXTERNAL)
ENGINE OIL DRAIN PLUGS AND GASKETS
ENGINE OIL FILTERS AND CANISTERS
ENGINE OIL GASKETS
ENGINE OIL PRESSURE GAUGES (MECHANICAL)
EVAPORATIVE EMISSION (EVAP) CANISTER FILTERS
EVAPORATIVE EMISSION (EVAP) CANISTER PURGE DEVICES
EVAPORATIVE EMISSION (EVAP) CANISTERS
EVAPORATIVE EMISSION (EVAP) FEEDBACK DEVICES
EXHAUST GAS RECIRCULATION DEVICES
EXHAUST GAS RECIRCULATION FEEDBACK DEVICES
EXPANSION PLUGS
FAN CONTROL SENSORS
FUEL
FUEL ACCUMULATORS AND DAMPERS
FUEL AND COLD START INJECTORS
FUEL DAMPERS
FUEL DELIVERY CHECK VALVES
FUEL DISTRIBUTORS (BOSCH CIS)
FUEL FILLER NECKS AND RESTRICTORS
FUEL FILTERS
FUEL INJECTORS
FUEL LEVEL SENDERS7
FUEL PRESSURE REGULATORS
FUEL PUMPS (IN-TANK AND EXTERNAL, ELECTRICAL OR MECHANICAL)
FUEL RAILS
FUEL RESTRICTORS

exposed ................ B .. Require repair or replacement.
Wire lead corroded ...... A .. Require repair or replacement.
Wire lead open .......... A .. Require repair or replacement.
Wire lead shorted ....... A .. Require repair or replacement.
(1) - Determine cause and correct prior to repair or
replacement of part.
( 2) - Inoperative includes intermittent operation or out of OEM
specification. Some components may be serviceable;
check for accepted cleaning procedure.
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COLD START INJECTORS
See FUEL AND COLD START INJECTORS .
CONNECTORS
See WIRING HARNESSES AND CONNECTORS .
COOLANT
COOLANT INSPECTION \
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Condition Code Procedure
Acidity (pH) incorrect .. 1 ........... Suggest correction or
replacement.
Contaminated ............ B ...... ( 1) Require replacement or
recycling. Further inspection
required.
Level low ............... B ... ( 2) Require filling to proper
level.
Maintenance intervals ... 3 ........ ( 3) Suggest replacement.
Mixture incorrect ....... B ........... Require correction or
replacement.
Type incorrect .......... B ............ Require replacement.
( 1) - Determine source of contamination and require
correction prior to coolant replacement.
( 2) - Determine source of incorrect level and suggest repair.
( 3) - The system should be drained and/or flushed and
refilled with correct coolant according to OEM
recommended service interval and procedures.
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COOLANT RECOVERY TANKS
COOLANT RECOVERY TANK INSPECTION \
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Condition Code Procedure
Attaching hardware
broken ................. A .. Require repair or replacement
of hardware.
Attaching hardware
missing ................ C ......... Require replacement of
hardware.
Attaching hardware not
functioning ............ A .. Require repair or replacement
of hardware.
Leaking ................. A . Require repair or replacement.

Condition Code Procedure
Contaminated ............ B ........... (1) Require repair or
replacement.
Fuel incorrect .......... B ......... ( 2) Require flushing of
system.
( 1) - Determine of source of contamination. Require repair or
replacement.
( 2) - If a fuel other than specification fuel is present in the
system, the required service is to flush and fill with the
correct fuel.
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FUEL ACCUMULATORS AND DAMPERS
FUEL ACCUMULATOR AND DAMPER INSPECTION \
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Condition Code Procedure
Attaching hardware
broken ................. A ... Require repair or replacement
of hardware.
Attaching hardware
missing ................ C .......... Require replacement of
hardware.
Attaching hardware not
functioning ............ A ... Require repair or replacement
of hardware.
Connections leaking ..... A .. Require repair or replacement.
Inoperative ............. A ........ ( 1) Require replacement.
Leaking ................. A ............ Require replacement.
( 1) - Inoperative includes intermittent operation or out of
OEM specification.
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FUEL AND COLD START INJECTORS
NOTE: You are not required to replace injectors in sets. However,
you may suggest replacement of all injectors for
preventive maintenance.
FUEL AND COLD START INJECTOR INSPECTION
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Condition Code Procedure
Application incorrect ... B ............ Require replacement.
Attaching hardware
broken ................. A ... Require repair or replacement
of hardware.
Attaching hardware
missing ................ C .......... Require replacement of
hardware.
Attaching hardware not
functioning ............ A ... Require repair or replacement
of hardware.
Connector broken ........ A .. Require repair or replacement.
Connector (Weatherpack
type) leaking .......... A .. Require repair or replacement.
Connector melted ........ A ........... ( 1) Require repair or
replacement.
Connector missing ....... C ............ Require replacement.

performance ............ A ........... (2) Require repair or
replacement. Further
inspection required.
( 1) - Inoperative includes intermittent operation.
( 2) - Some components may be serviceable; check for accepted
cleaning procedure.
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FUEL FILLER NECKS AND RESTRICTORS
FUEL FILLER NECK AND RESTRICTOR INSPECTION \
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Condition Code Procedure
Attaching hardware
broken ................. A ... Require repair or replacement
of hardware.
Attaching hardware
missing ................ C .......... Require replacement of
hardware.
Attaching hardware not
functioning ............ A ... Require repair or replacement
of hardware.
Leaking ................. A .. Require repair or replacement.
Missing ................. C ............ Require replacement.
Restricted .............. 2 .. Suggest repair or replacement.
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FUEL FILTERS
FUEL FILTER INSPECTION \
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Condition Code Procedure
Attaching hardware
broken ................. A ... Require repair or replacement
of hardware.
Attaching hardware
missing ................ C .......... Require replacement of
hardware.
Attaching hardware not
functioning ............ A ... Require repair or replacement
of hardware.
Leaking ................. A .. Require repair or replacement.
Maintenance interval .... 3 ... Suggest replacement to comply
with OEM recommended service
interval.
Missing ................. C ............ Require replacement.
Restricted, affecting
performance ............ A ............ Require replacement.
Restricted, not affecting
performance ............ 1 ............ Suggest replacement.
Water-contaminated ...... 2 ............ Suggest replacement.
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FUEL INJECTORS
FUEL INJECTOR INSPECTION \
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Condition Code Procedure
Attaching hardware

Wire lead open .......... A .. Require repair or replacement.
Wire lead shorted ....... A .. Require repair or replacement.
(1) - Determine cause and correct prior to repair or
replacement of part.
( 2) - Determine source of contamination, such as engine coolant,
fuel, metal particles, or water. Require repair or
replacement.
( 3) - Inoperative includes intermittent operation or out of
OEM specification. Some components may be serviceable;
check for accepted cleaning procedure.
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SENSORS AND ACTUATORS
NOTE: Conditions pertaining to the sensors and actuators listed
in this section may be found under the name of the sensor
or actuator.
SENSOR ABBREVIATION TABLE
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Sensor Abbreviation
Accelerator Pedal Position Sensor ......................... APP
Air Conditioning Cycling Switch ............................ AC
Air Conditioning Pressure Sensor ........................... ..
Air Fuel Ratio Sensor ...................................... ..
Barometric Pressure Sensor ............................... BARO
Camshaft Position Sensor .................................. CMP
Clutch Pedal Position Switch .............................. CPP
Cooling Fan Motor Sensors and Switches ..................... ..
Crankshaft Position Sensor ................................ CKP
Electronic Transmission Feedback Devices ................... ..
Engine Coolant Temperature Sensor ......................... ECT
Evaporative Emission feedback devices ...................... ..
Exhaust Gas Recirculation feedback devices ................. ..
Fan Control Sensor ......................................... FC
Intake Air Temperature Sensor ............................. IAT
Knock Sensor ............................................... KS
Manifold Absolute Pressure Sensor ......................... MAP
Mass Air Flow Sensor ...................................... MAF
O2 Sensor ................................................. O2S
Park Neutral Position Switch .............................. PNP
Power Steering Pressure Sensor ............................ PSP
Thermal Vacuum Valve ...................................... TVV
Throttle Position Sensor ............................ TP Sensor
Throttle Position Switch ................................... ..
Transmission Range Switch ........................... TR Switch
Vehicle Speed Sensor ...................................... VSS
Volume Air Flow Sensor .................................... VAF
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ACTUATOR ABBREVIATION TABLE \
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Actuator Abbreviation
Air Injection Control Solenoid ............................. ..
Electronic Transmission control devices .................... ..
Evaporative Emission Canister ............................ EVAP
Purge Device ............................................... ..
Exhaust Gas Recirculation Device .......................... EGR
Fuel Injector .............................................. ..
Idle Air Control .......................................... IAC

Brake On/Off (BOO) Switch ................... Cruise Control Systems\
Engine Performance
Shift Interlock Systems
Buzzer Module ...................................... Warning Systems
Camshaft Position (CMP) Sensor .................. Engine Performance\
Central Control Module ........................... Anti-Theft System
Clockspring ............................... Air Bag Restraint System
Cruise Control Systems
Steering Column Switches
Clutch Pedal Position Switch .............................. Starters
Clutch Start Switch ....................................... Starters
Combination Meter ......................... Analog Instrument Panels
Constant Control Relay Module (CCRM) ............ Engine Performance\
Electric Cooling Fans
Convenience Center .............................. Power Distribution
Illumination/Interior Lights
Convertible Top Motor ........................ Power Convertible Top
Convertible Top Switch ....................... Power Convertible Top
Crankshaft Position (CKP) Sensor ................ Engine Performance\
Cruise Control Module ....................... Cruise Control Systems
Cruise Control Switch ....................... Cruise Control Systems
Condenser Fan Relay(s) ....................... Electric Cooling Fans\
Data Link Connector (DLC) ....................... Engine Performance\
Daytime Running Lights Module ............... Daytime Running Lights
Exterior Lights
Defogger Relay ................................ Rear Window Defogger
Diagnostic Energy Reserve Module (DERM) ... Air Bag Restraint System\
Discriminating Sensor (Air Bag) ........... Air Bag Restraint System\
Distributor ..................................... Engine Performance
Door Lock Actuators ............................... Power Door Locks
Remote Keyless Entry
Door Lock Relay(s) ................................ Power Door Locks\
Electrochromic Mirror ................................ Power Mirrors
Electronic Level Control (ELC)
Height Sensor .............................. Electronic Suspension
Electronic Level Control (ELC) Module ........ Electronic Suspension\
Engine Coolant Temperature (ECT)
Sending Unit ............................ Analog Instrument Panels
Engine Coolant Temperature (ECT) Sensor ......... Engine Performance\
Engine Control Module ........................... Engine Performance
Generators & Regulators
Starters
ETACS ECU .......................................... Warning Systems
Power Windows
Remote Keyless Entry
Evaporative (EVAP) Emissions Canister ........... Engine Performance\
EVAP Canister Purge Solenoid .................... Engine Performance
EVAP Canister Vent Solenoid ..................... Engine Performance
Exhaust Gas Recirculation (EGR) Valve ........... Engine Performance\
Fuel Tank Vacuum Sensor ......................... Engine Performance
Fog Lights ....................................... Headlight Systems
Daytime Running Lights
Fog Light Relay .................................. Headlight Systems
Daytime Running Lights
Fuel Door Release Solenoid ................. Power Fuel Door Release
Fuel Gauge Sending Unit ................... Analog Instrument Panels
Fuel Injectors .................................. Engine Performance
Fuel Pump ....................................... Engine Performance
Fuel Pump Relay ................................. Engine Performance
Power Distribution
Fuse/Relay Block ................................ Power Distribution
Fusible Links ................................... Power Distribution
Generators & Regulators