oil change PONTIAC FIERO 1988 Service Owner's Guide

DRIVEABILITY AND EMISSIONS 5.OL (VIN F) & 5.7L (VIN 8) 6E3-C2-1
SECTION C2
FUEL CONTROL SYSEENI
CONTENTS
GENERAL DESCRIPTION . . . . . . . . . . . . . . . . C2-1
PURPOSE ........................ C2-1
MODES OF OPERATION . . . . . . . . . . . . . . C2-2
Starting Mode . . . . . . . . . . . . . . . . . . . C2-2
Clear Flood Mode.. . . . . . . . . . . . . . . . C2-2
Run Mode.. . . . . . . . . . . . . . . . . . . . . . C2-2
Acceleration Mode.. . . . . . . . . . . . . . . C2-2
Deceleration Mode . . . . . . . . . . . . . . . C2-3
Battery Voltage Correction Mode . . . . . C2-3
Fuel Cutoff Mode . , . . . . . . . . . . . . . . . C2-3
FUEL CONTROL SYSTEM . . . . . . . . . . . . . . C2-3
Basic System Operation . . . . . . . . . . . . C2-3
Throttle Body Unit . . . . . . . . . . . . . . . . C2-3
Fuel Rail . . . . . . . . . . . . . . . . . . . . . . . C2-3
Fuel Injectors . . . . . . . . . . . . . . . . . . . . C2-3
Pressure Regulator . . . . . . . . . . . . . . . C2-4
IAC Valve . . . . . . . . . . . . . . . . . . . . . . . C2-4
Fuel Pump Electrical Circuit . . . . . . . . , C2-5
DIAGNOSIS
......................... C2-5
FUEL CONTROL SYSTEM . . . . . . . . . . . . . . C2-5
IDLE AIR CONTROL VALVE . . . .. 0.. . a. C2-5
FUEL SYSTEM PRESSURE TEST . .. . . . . . . C2-5
ON-CAR SERVICE
. . . . . . . . . . . . . . . . . . . . . C2-5
PORT FUEL INJECTION COMPONENTS . . . . C2-5
FUEL PRESSURE RELIEF PROCEDURE . . . . . C2-5
Plenum ........................ C2-5
FUEL RAlL ASSEMBLY . . . . . . . . . . . . . . . . C2-6
FUEL
RAlL SERVICE . . . . . . . . . . . . . . . . . . . C2-7
IDENTIFICATION . . . . . . . . . . . . . . . . . . . C2-7
UNlT SERVICE PROCEDURES .. . . . . . . . .. C2-7
COLD START TUBE & VALVE ASSEMBLY.. . C2-7
PARTS INFORMATION
. . . . . . . . . . . . . . . C2-9
FUEL PRESSURE CONNECTION ASSY. . . . . C2-10
FUEL INJECTORS (Rail Removed) . . . . . . . . C2-10
PRESSURE REGULATOR (Rail Removed) . . . C2-10
COLD START FUEL INJECTION SWITCH . . . C2-11
THROTTLEBODY ................... C2-11
THROTTLE BODY SERVICE IDENTIFICATION
. C2-12
UNlT REPAIR PROCEDURES . . . . . . . . . . . . C2-12
TPS Adjustment .............. C2-12
MINIMUM IDLE SPEED CHECK . . . . . . . . . . . C2-12
PARTSINFORMATION ................. C2-15
IDLE AIR C'NT' L VALVE ASSY & GASKET . . C2-15
CLEAN AIR COVER &GASKET . . . . . . . . . . C2-15
IDLE AIR CONTROUCOOLANT CVR. ASSY . C2-15
Throttle Body Removed From Engine . . C2-15
FUEL PUMP RELAY . . . . . . . . . . . . . .,. . . . C2-16
OIL PRESSURE SWITCH . . . . . . . . . . . . . . . C2-16
PARTS INFORMATION . . . . . . . . . . . . . . . . . C2-16
GENERAL DESCRIPTION
PURPOSE
The basic function of the fuel control system is to
control fuel delivery to the engine.
Fuel is delivered to the engine by individual fuel
injectors mounted in the intake manifold near each
cylinder.
The main control sensor is the oxygen
(02) sensor,
which is located in the exhaust manifold. The
O2
sensor tells the electronic control module (ECM) how
much oxygen is in the exhaust gas.
The ECM changes
the
airlfuel ratio to the engine by controlling the fuel
injectors.
The best mixture to minimize exhaust
emissions is
14.7 to 1, which allows the catalytic
converter to operate the most efficiently. Because of
the constant measuring and adjusting of the
airlfuel
ratio, the fuel injection system is called a "Closed
Loop" system (shown in Figure
C2-I).
EXHAUST OXYGEN 02 SENSOR
CATALYTIC CONVERTER
Figure C2-1 "Closed Loop" System

DRIVEABILITY AND EMISSIONS 5.OL (VIN F) & 5.7L (VIN 8) 6E3-CZ-3
Deceleration Mode
The ECM looks at changes in throttle position and
air flow to reduce the amount of fuel. When
deceleration is very fast, the ECM may shut off fuel
completely for short periods.
Battery Voltage Correction Mode
When battery voltage is low, the ECM can
compensate for the weak spark delivered by the
distributor by:
@ Increasing the amount of fuel delivered;
@ Increasing the idle rpm; and
@ Increasing ignition dwell time.
Fuel Cutoff Mode
No fuel is delivered by the injector when the
ignition is "OFF". This prevents dieseling. Also, fuel
is not delivered if no reference pulses are seen from
the distributor, which means the engine is not
running. This prevents flooding.
FUEL CONTROL SYSTEM
Basic System Operation
The fuel system (Figure C2-3) starts with the fuel
in the fuel tank.
An electric fuel pump, located in the fuel tank with
the gage sending unit, pumps
fuel to the fuel rail
through an in-line fuel filter. The pump is designed to
provide fuel at a pressure above the pressure needed
by the injectors. A pressure regulator in the fuel rail
keeps fuel available to the injectors at
a constant
pressure, depending on manifold pressure. Unused
fuel is returned to the fuel tank by a separate line. For
further information on the fuel tank, in-line filter, and
fuel lines, see Section
"6C".
The injectors are controlled by the ECM. They
deliver fuel in one of several modes, as described
above. In order to properly control the fuel supply, the
fuel pump is operated by the
ECM through the fuel
pump relay and oil pressure switch (see Fuel Pump
Electrical Circuit Code
54).
Throttle Body Unit
The throttle body has a throttle valve to control
the amount of air delivered to the engine. The TPS
and the IAC valve are also mounted on the throttle
body. The throttle body contains vacuum ports located
at, above, or below the
throttIe valve. 'I'hese ports
generate the vacuum signals
needed I,y v~irious
Figure C2-3 Fuel System
components. Engine coolant is directed through the
coolant cavity, on the bottom of the throttle body, to
warm the throttle valve and prevent icing.
Fuel Rail
The fuel rail is mounted to the top of the engine. It
distributes fuel to the individual injectors. Fuel is
delivered to the input end of the rail by the fuel lines,
goes through the rail, then to the pressure regulator.
Remaining fuel is then returned to the fuel tank.
Fuel Injectors
The fuel injector is a solenoid operated device
controlled by the ECM (see Figure
C2-4). The ECM
turns
"ON" the solenoid, which opens a valve to allow
fuel delivery.
The fuel, under pressure, is injected in a
conical spray pattern at the opening of the intake
valve. The fuel, which is not used by the injectors,
passes through the pressure regulator before being
returned to the fuel tank.
An injector which is stuck partly open will cause
loss of pressure after engine shut down, so long crank
times would be noticed on some engines. Also,
dieseling could occur because some fuel could be
delivered to the engine after the ignition is turned
"OFF".

DRIVEABILITY AND EMISSIONS 5.OL (VIN F) & 5.7L (VIN 8) 6E3-C2-5
Fuel Pump Electrical Circuit
When the ignition is first turned "ON", without
the engine running, the ECM will turn the fuel pump
relay "ON" for two seconds.
This builds up the fuel
pressure quickly. If the engine is not started within
two seconds, the ECM will shut the fuel pump "OFF"
and wait until the engine is cranking. As soon as the
engine is cranked, the ECM will turn the relay "ON"
and run the fuel pump.
As
a backup system to the fuel pump relay, the
fuel pump can also be turned "ON" by the oil pressure
switch. The oil pressure switch is a normally open
switch which closes when oil pressure reaches about
28
kPa (4 psi). If the fuel pump relay fails, the oil
pressure switch will close, and run the fuel pump.
An inoperative fuel pump relay can result in long
cranking times, particularly if the engine is cold but
should result in
a Code 54.
An inoperative fuel pump would cause a no start
condition. A fuel pump which does not provide enough
pressure can result in poor performance.
DIAGNOSIS
FUEL CONTROL SYSTEM
Some failures of this system will result in an
"Engine Cranks But Won't Run". If
this condition
exists see CHART A-3. This chart will determine if
the problem is caused by the ignition system, ECM, or
fuel pump circuit. If
it's determined to be a fuel
problem CHART A-7 will be used. This includes the
injectors, pressure regulator, fuel pump, and fuel
pump relay. The fuel system wiring schematic is
covered on the facing page of Code CHART 54.
If a malfunction occurs in the fuel control system,
it usually results in either a rich or
a lean exhaust
condition. This condition is sensed by the oxygen
sensor and the ECM will change the fuel calculation
(injector pulse width) based on the
O2 sensor reading.
The change
made to the fuel calculation will be
indicated by a change in the block learn values, which
can be monitored by a "Scan" tool.
The normal block
learn values are around 128, and if the
O2 sensor is
sensing a lean condition, the EC
M will add fuel which
will result in a block learn value above 128.
If the O2
sensor is sensing a rich exhaust the ECM will reduce
fuel to the engine and this will result in block learn
values below 128. Some variations in block
learn
values are normal because all engines are not exactly
the same. However, if the block learn values are
+ 10
counts from 128 a system problem exists. If the block
learn values are greater than 138 see Code 44, for
items which can cause a lean system.
If the block learn values are less than 118 see Code
45 for items which can cause the system to run rich. If
a driveability symptom exists, refer to the
particular symptom in Section
"B" for additional
items to check.
IDLE AIR CONTROL VALVE
AUScan" tool will read IAC position in steps (counts).
"0" steps indicates the ECM is commanding the IAC to
be driven all the way in, to a fully seated position, and
this is usually caused by a vacuum leak. The higher
the number of counts the more air being allowed to
pass the IAC valve. CHART C-2C can be used to
diagnosis the IAC valve. Also refer to "Rough,
Unstable, or Incorrect Idle, Stalling" in symptoms,
Section "B" for other possibilities for the cause
of idle
problems.
FUEL SYSTEM PRESSURE TEST
A fuel system pressure test is part of several of the
diagnostic charts and symptom checks. To perform
this test, use the procedure in CHART A-7.
ON-CAR SERVICE
PORT FUEL INJECTION COMPONENTS
CAUTION:
Before servicing an injector, fuel
rail, or pressure regulator,
it is
necessary to relieve the pressure in
the fuel system, to minimize the
risk of fire and personal injury.
(See "Fuel Pressure Relief
Procedure" below). To reduce the
chance of personal injury, cover
the fuel line with
a shop cloth to
collect the fuel, and then place the
cloth in an approved container.
FUEL PRESSURE RELIEF PROCEDURE
1. Connect fuel gage J 34730-1 or equivalent to fuel
pressure valve. Wrap a shop towel around fitting
while connecting gage to avoid spillage.
2. Install bleed hose into an approved container and
open valve to bleed system pressure.
Plenum
(Figure
C2-6)
Remove or Disconnect
1. Negative battery cable.
2. Throttle, 'F.V., and cruise control cable.
3. Cable retaining bracket.
4.
'I'hrottle body retaining bolts (4).
5. 'L'l'S and IAC valve electrical connectors.
6. Vacuum hoses.

6E3-C2-20 5.0L (VIN F) & 5.7L (WIN 8) DRIVEABILITY AND EMISSIONS
CONNECTOR - 441 BLUMlHT C5 IAC C0lL1'A" HI - 442 BLUIBLK C6 IAC COIL "A" LO - 443 GRNMlHT C4 IAC COIL "B" HI - 444 GRNIBLK C3 lAC COIL "B" LO v
START VALVE
CHART C-2C
IDLE AIR CONTROL (IAC) SYSTEM CHECK
S.OL (VIN F) & 5.7L (VIN 8) "F'" SERIES (PORT)
Circuit Description:
The ECM will control engine idle speed by moving the IAC valve to control air flow around the throttle
plates. It does this by sending voltage pulses to the proper motor winding for each IAC motor. This will cause
the motor shaft and valve to move
"IN" or "OUT" of the motor a given distance for each pulse received. ECM
pulses are referred to as "counts".
@ To increase idle speed - ECM will send enough counts to retract the IAC valve and allow more air to flow
through the idle air passage and bypass the throttle plates until idle speed reaches the proper rpm. This
will increase the ECM counts.
e To decrease idle speed - ECM will send enough counts to extend the IAC valve and reduce air flow through
the idle passage around the throttle plates. This will reduce the ECM counts.
Each time the engine is started and then the ignition is turned "OFF", the ECM will reset the IAC valve.
This is done by sending enough counts to seat the valve.
The fully seated valve is the ECM reference zero. A
given number of counts are then issued to open the valve, and normal ECM control of IAC will begin from this
point. The
number of counts are then calculated by the ECM. This is how the ECM knows what the motor
position is for a given idle speed.
The ECM uses the following information to control idle speed.
@ Battery voltage @ Engine speed @ Coolant temperature @ Throttle position sensor @ PIN switch e A/C clutch signal
Don't apply battery voltage across the IAC motor terminals. It will permanently damage the IAC motor
windin s. Test 6escription: Numbers below refer to circled
numbers on the diagnostic chart.
1. Continue with test, even if engine will not idle. If
idle is too low, "Scan" will display 80 or more
counts, or steps. If idle is high, it will display
"0"
counts.
Occasionally an erratic or unstable idle
[nay occur. Engine speed may vary 200 rpm or more up
and down. Disconnect IAC. If the condition is
unchanged, the IAC is not at fault.
There is a
system problem. Proceed to "Diagnostic Aids"
below.
2. When the engine was stopped, the IAC valve
retracted (more air) to
a fixed "Park" position for
increased air flow and idle speed during the next
engine start. A "Scan" will display 140 or more
coiints. 3. Be sure to disconnect the IAC valve prior to this
test.
The test light will confirm the ECM signals
by a steady or flashing light on all circuits.
4. There is a remote possibility that one of the
circuits is shorted to voltage which would have
been indicated by a steady light. Disconnect ECM
and turn the ignition "ON" and probe terminals to
check for this condition.
Diagnostic Aids:
Engine idle speed can be adversely affected by the
following:
@ ParMNeutral switch - If ECM thinks the car is
always in neutral, then idle will not be controlled
to the specified rpm when in drive range.
@ Leaking injector(s) will cause fuel imbalance and
poor idle quality due to excess fuel. See CHT.
A-7. @ Vacuum or crankcase leaks can affect idle. @ Whenthethrottleshaftorthrottlepositionsensor
is binding or sticking in an open throttle position,
the ECM does not know if the vehicle has stopped
and does not control idle.
@ Check A.I.R. management s stem for intermittent
air to orts while in "~losed~oo~". @ In ad&tion to electrical control of EGR, be sure to
examine the EGR valve for proper seating.
@ Faulty battery cables can result in voltage
variations. The ECM will try to compensate,
which results in erratic idle speeds.
@ 'I'he ECM will com ensate for A/C com ressor
clutch loacls. [.ass ofthe NC request sign8 would
he 11lost apparent, in neutral. @ Contalninatecl fuel can adverse1 affect idle. @ Perform i~!jector balance test C~ART C-2A. If ,111 OK, refer to "Rough, Unstable, Incorrect Idle or St ,tllinqW SJ tnptcfinsiin S~'ction "11''.

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.

AUTOMATIC TRANSMISSION 700-R4-1
AUTOMAT C TRANSM
CONTENTS
TRANSMISSION DISASSEMBLY
.............. General Service Information 700-R4-4
........................................... Disassembly 700-R4-4
2-4 Servo Assembly
................................. 700-R4-4
.................................. Servo Pin Length 700-R4-4
........................ Governor And Extension 700-R4-4
Valve Body And Wiring Harness
........... 700-R4-5
................ Transmission End Play Check 700-R4-6
Oil Pump Assembly
................................ 700-R4-7
2-4 Band. Reverse Input Clutch.
.................. Input And Input Gear Set 700-R4-8
Reaction Gear Set
................................. 700-R4- 10
.............. Lo And Reverse Clutch Parts 700-R4-10
COMPONENT REPAIR AND
TRANSMISSION ASSEMBLY
Inner Manual Linkage .......................... 700-R4- 10
........... Manual Shaft Seal Replacement 700-R4-10
Case
...................................................... 700-R4- 13
Third Accumulator Retainer And
Check Ball Assembly
........................ 700-R4- 15
Case Assembly
............................. ., ...... 700-R4- 18
Lo And Reverse Clutch Assembly
....... 700-R4- 18
*Lo and Reverse Clutch Backing
Plate Selection
.................................. 700-R4- 19
..................................... Parking Pawl 700-R4- 18
Reaction Internal Gear And
Carrier Assembly
.............................. 700-R4- 18
Reaction Internal Gear And Support
... 700-R4- 19
Lo And Reverse Support Assembly
..... 700-R4-20
Reaction Sun Gear And Shell
.............. 700-R4-21
Input Internal Gear And Output
.................. Shaft .......................... ... 700-R4-22
................ Input Carrier And Sun Gear 700-R4-24 *Input
Clutch Assembly
....................... 700-R4-25
Check Valve Retainer and Ball
Assembly Replacement Procedures
. . 700-R4-26
Forward Clutch Sprag Assembly
......... 700-R4-30
*3-4 Clutch Assembly
.......................... 700-R4-32
......... "3-4 Clutch Piston Travel Check 700-R4-32
Clutch Air Check
................................. 700-R4-33
......... *Reverse Input Clutch Assembly 700-R4-33
"Reverse Input Clutch
Backin~Plate
Selection ...................................... 700-R4-34
Reverse Input And Input Clutches
...... 700-R4-35
2-4 Band Assembly
.............................. 700-R4-35
*Oil Pump Assembly
............................ 700-R4-36
"Pump Body .......................................... 700-R4-36
Oil Pump Cover
.................................... 700-R4-36
Oil Pump Body And Cover
.................. 700-R4-39
Transmission End Play Check
.............. 700-R4-4 1
....... Valve Body And Associated Parts 700-R4-44
*Control Valve Assembly
..................... 700-R4-45
*2-4 Servo Assembly
............................. 700-R4-5 1
Governor Assembly ............................... 700-R4-52
........................................... Speedometer 700-R4-55
Torque Converter Assembly
................. 700-R4-55
SEALS AND BEARING
....................................... LOCATIONS 700-R4-58
TORQUE SPECIFICATIONS AND
.................. BUSH l NG LOCATIONS 700-R4-59
BUSHING REPLACEMENT
..................................... PROCEDURE 700-R4-60
GOVERNOR BORE REPAIR
PROCEDURE
......................... ............ 700-R4-63
...... ...................... SPECIAL TOOLS .. 700-R4-64
*Designates significant product changes
since the publication of the
1987 Service
Manual .

7A-2 AUTOMATIC TRANSMISSION
I I
M - INDICATES TRANSMISSION
TYPE IN OPTION LIST. (SPECIFIC MODEL CODE IS FOUND ON THE I MX - DESIGNATES
11 SERVICE PARTS IDEMTIFICATIOM I 1 00 MOT REMOVE I
1G3AR47YXE5
C90 C95 DF3 D3C 033 0 GI GW9 G60 GU2 G89
JAl JA4 KO5 K22 Kg9 LV2 NA5 NB1 NKl NK3 N33 N67 GJW
T87 UJ3 U23 U35
VO8 V10 WC3 WG2 YT9 Y56 OIL 6SC 428 421 420
Figure 2 Service Parts ldentificaiton Label
TRANSMISSION DEFINITIONS
The following definitions are being provided to
establish a common language and assist the user in
describing transmission related conditions. Some of
these terms or conditions are used in the transmission
sections of this Service Manual.
Throttle Positions
Minimum Throttle - the least amount of
throttle opening required for an upshift.
Light Throttle - approximately 1/4 of
accelerator pedal travel.
Medium Throttle - approximately 1/2 of
accelerator pedal travel.
Heavy Throttle - approximately 3/4 of the
accelerator pedal travel.
Wide Open Throttle (WOT) - full travel of
the accelerator pedal.
Full Throttle Detent Downshift - a quick
apply of the accelerator pedal to its full travel,
forcing a downshift.
Zero Throttle Coastdown - a full release of
the accelerator pedal while the vehicle is in
motion and in drive range.
Engine Braking - a condition where the engine
is used to slow the vehicle by manually
downshifting during a zero throttle coastdown.
Shift Conditions
'a Bump - a sudden and forceful apply of a clutch
or band.
Q Chuggle - a bucking or jerking condition that
may be engine related. May be most noticeable
when the converter clutch is engaged. Similar to
the feel of towing a trailer.
e Delayed - a condition where a shift is expected
but does not occur for a period of time. Samples
of this condition could be described as clutch or
band engagement does not occur as quickly as
expected during a part throttle or wide open
throttle apply of the accelerator or, when
manually downshifting to a lower range. Also
defined as "LATE" or, "EXTENDED."
Double Bump ("Double Feel") - two sudden
and forceful applies of a clutch or band.
Early - a condition where the shift occurs before
the vehicle has reached a proper speed and tends
to labor the engine after the upshift.
End Bump - a firmer feel at the end of a shift as
compared to the feel at the start of the shift. Also
defined as "END FEEL" or, "SLIP BUMP."
Firm - a noticeable quick apply of a clutch or
band that is considered
normal with a medium
to heavy throttle shift. Should not be confused
with "HARSH" or "ROUGH."
Flare - a quick increase in engine rpm
accompanied with a momentary loss of torque.
This most generally occurs during a shift. Also
defined as "SLIPPING.
"
Harsh ("Rough") - a more noticeable apply of
a clutch or band as compared to "FIRM." This
condition is considered undesireable at any
throttle position.
Hunting - a repeating quick series of upshifts
and downshifts that causes a noticeable change in
engine rpm. An example could be described as a
4-3-4 shift pattern. Also defined as
"BUSYNESS.
"
Initial Feel - a distinct firmer feel at that start
of a shift as compared to the finish of the shift.
Late - a shift that occurs when the engine is at
a higher than normal rpm for a given amount of
throttle.
Shudder - a repeating jerking sensation similar
to "CHUGGLE" but more severe and rapid in
nature. This condition may be most noticeable
during certain ranges of vehicle speed. May also
be used to define the condition after converter
clutch engagement.
Slipping - a noticeable increase in engine rpm
without a vehicle speed increase.
A slip usually
occurs during or after initial clutch or band
engagement.
Soft - a slow, almost unnoticeable clutch apply
with very little shift feel.
Surge - a repeating engine related feeling of
acceleration and deceleration that is less intense
than "CHUGGLE.
"
Tie-Up - a condition where two opposing
clutches are attempting to apply at the same time
causing the engine to labor with a noticeable loss
of engine rpm.
,e Conditions
Gear Noise - a whine, most noticeable in first
gear and reverse that is related to vehicle speed.
A gear noise condition may become less
noticeable or go away after an upshift.
Pump Noise - a high pitch whine that increases
in intensity with engine
rpm. This condition may
also be noticeable in
"PARK" and "NEUTRAL"
operating ranges with the vehicle stationary.

CRUISE CONTROL
(Continued from previous page)
TEST I: RIA CIRCUIT OPEN
Disconnect C223 and check switch continuity
between terminals A (BLU) and C (YEL) of the
pin half of the Cruise Switch in RIA.
0 If the switch is open, replace the Multi-Func-
tion Lever.
If the switch is not open, check for an open in
the
GRYIBLK (87) wire between terminal C
of connector C223 at terminal M of the Mod-
ule.
TEST J: VENT CIRCUIT SHORT
Remove the connector from the Servo and mea-
sure resistance between terminals
A and C of
the Servo.
If it is less than 30 ohms, replace the Servo.
If it is 30 ohms or more, check for a short to
ground in the DK
BLUIWHT wire from ter-
minal C of the Module to terminal A of the
Servo.
TEST K: VSS ClRCUlT OPEN
If the VSS light does not come on, or the volt-
age between terminals A (GRY) and D (BRN)
remains less than 7 volts, check for an open in
the BRN (437) wire or the RED (381) wire from
the Vehicle Speed Sensor Buffer. Refer to page
33-0 for diagnosis of Vehicle Speed Sensor.
TEST L: VSS CIRCUIT SHORT
If the VSS lights does not go off or Battery
voltage remains between ter
and D
(BRN), check for a short to ground on the
BRN (437) wire or the RED (381) wire from the
Vehicle Speed Sensor Buffer. Refer to page 33-0
for diagnosis of Vehicle Speed Sensor.
TEST M: VACUUM SYSTEM
1. Check for a blocked or leaking vacuum
source.
2. If the vacuum source is good, plug the Vac-
uum Release Port and repeat Test
6 of the
Isolation Test.
If the vacuum now holds the throttle open,
replace or repair the Vacuum Release Valve
or the hose to it.
If the test still fails, replace the Cruise Con-
trol Servo.
TEST N: SPS CIRCUIT SHORT
Disconnect the Cruise Control Servo connector
and repeat Test 7 of the Isolation Test.
If the resistance is now over range, replace
the Cruise Control Servo.
If the resistance is still low, find and repair
the short in the TAN wire from terminal F of
the Cruise Control Module to terminal B of
the Cruise Control Servo.
ClRCUlT OPERATION
The Cruise Control System operates a
mechanical linkage to the throttle by means of a
Vacuum Motor. This is a diaphragm moved by
a vacuum applied to one side. A solenoid oper-
ated valve connects the Vacuum Motor to a
Vacuum Tank. Another solenoid valve vents
the vacuum to reduce the suction. The Cruise
Control Module controls the Vacuum Motor
and the throttle by pulsing these solenoid
valves on and off.
One input to the Module is the vehicle speed.
This input comes from the Vehicle Speed Sen-
sor. If the actual speed signal is different from
the speed that was set into and remembered by
the Module, the Module generates pulses to
change the vacuum and return the vehicle to
the set speed. The Vehicle Speed Sensor is
mounted on the Transmission. Other inputs to
the Module are from the Cruise Switch and the
Set Switch. A disengage input to the Module
comes from a switch on the brake pedal. A
sepe-
rate vacuum shut down of the Cruise Control
comes from the Vacuum Release Valve on the
brake pedal.
The two outputs of the Cruise Control Mod-
ule operate the coils of the Vacuum Valve and
the Vent Valve. Both valves are located in the
Cruise Control Servo. These valves move the
throttle be means of the Vacuum Motor. The
Servo Position Sensor
(SPS) coil senses the
position and motion of the Vacuum Motor. It
feeds this information back to the Module to
provide smooth acceleration while the vehicle is
in Cruise Control.

(Continued from previous page)
If the Speedometer reads correctly, refer to
Vehicle Speed Sensor, Section
8A-33 for fur-
ther diagnosis.
If the Speedometer reads incorrectly, check
LT GRN (537) wire and the Instrument Clus-
ter Printed Circuit for opens. Replace the
Speedometer Assembly if the wire and
Printed Circuit are good (see Section
8C).
O: UPSHIFT INDICATOR WIRE TEST
Disconnect ECM connector C207. Put the Igni-
tion Switch in RUN and measure the voltage at
terminal
H (see section 8A-21 or 22).
If battery voltage is present, see section
6E
for ECM diagnosis.
If battery voltage is not present, check the
TANIBLK (422) wire for an open or short to
Ground.
CIRCUIT OPERATION
The operation of an indicator is explained in
the operation of the circuit it is apart of. See the
circuit referred to for a complete description of
that indicator and the other components that
work with it. Only the gages and indicators that
do not appear in other schematics are described
in this section.
Tachometer
The Tachometer displays engine speed in
rpm. Voltage pulses are taken from the Ignition
System and sent to the Tachometer. Solid State
circuits process these pulses into a signal that
drives the pointer of the meter. The Tachometer
responds to the frequency of the voltage pulses.
These pulses increase with engine speed.
Fuel Gage
The pointer of the Fuel Gage is moved by the
magnetic field of two coils. The coils are at right
angles to each other. Battery voltage is applied
to the E coil and the circuit divides at the
opposite end of this coil. One path continues to
ground through the F coil. Another goes to
ground through the variable resistor of the Fuel
Gage Sender Unit.
When the tank is low, the resistance of the
Fuel Gage Sender is low. A large flow of current
passes through the E coil and the Fuel Gage
Sender resistor. This moves the pointer
towards E on the scale. When the tank is
full,
the sender resistance is high. More current
flows through the F coil, moving the pointer
toward F on the scale.
With two coils operating the pointer, the Fuel
Gage is not affected by changes in the voltage
of the system.
011 Pressure Gage
The engine oil pressure is displayed by the Oil
Pressure Gage. The pointer of the gage is
moved by two coils, and its operation is similar
to that of the Fuel Gage. The
Oil Pressure Sender is connected to the
junction of the two coils.
It has low resistance
when the oil pressure is low, and 90 ohms
resistance when the oil pressure is high. This
changing resistance changes the current flow
through the coils. The magnetic fields of the
coils move the pointer to indicate high or low
coolant temperature.
Voltmeter
The Voltmeter measures the electrical sys-
tem voltage with the Ignition Switch in RUN,
BULB TEST, or START. With the engine
stopped, the Voltmeter indicates battery condi-
tion. With the engine
running, the Voltmeter
indicates Charging System operation.
Coolant Temperature Gage
The Coolant Temperature Gage is also oper-
ated by two coils. Battery voltage is applied to
both coils. One is grounded directly
and the
other is grounded through the Coolant Tem-
perature Sender. This has 54 ohms resistance at
260
OF, 130 "C (hot coolant) and its resistance
becomes greater at lower temperatures. It is
appr~ximately 1284 ohms at 100 OF (40 '6). This
causes the current through the sender and one
coil to vary as the coolant temperature charges
and this moves the pointer.

INSTRUMENT PANEL: DlGlTAL CLUSTER a
SYSTEM DIAGNOSIS
0 Do the tests listed for your symptom in the
Symptom Table below, or when
direded by
the System Check.
0 Tests follow the Symptom Table.
SYMPTOM TABLE
SYMPTOM FOR DIAGNOSIS
ENTIRE CLUSTER - -
0 Is Not Illuminated Do
Test B, Check Terminals 1, 27, and All Grounds
LCD Displays Do Not Operate Do
Test B, Check Terminals 13,
16,32, and All Grounds
Do Test A, Check C3 Terminals C, F, and All Grounds
I 0 Has Missing Display Senments I Replace Cluster (See Section 8C) I
Does Not Dim When Park Lights Go On Do
Test B, Check Terminals 9 and 10
Does Not Dim When
I/P Light Dimmer Is Adjusted Do
Test B, Check Terminal 10
0 Does Not Change Between English And Metric Or The Audio Replace
Cluster (See Section 8C)
Alarm Does Not Work
SPEEDOMETER1 Odometer Flashes 9999.9 Replace Memory Chip In Cluster (See Section 8Cl
ODOMETERS Tachometer Does Not Operate Do Test C TACHOMETER 0 Speedometer Does Not Operate, Odometers OK Replace Cluster (See Section 8C)
I 0 Trip Odometer Does ~otReset To Zero I Redace Cluster (See Section 8C) I
I COOLANT I 0 Always Reads Hot I Do Test D I
TEMPERATURE Is Not Accurate DISPLAY Do Test F
Always Reads Cold
Do Test E
I VOLTAGE DISPLAY I e Does Not Operate
FUEL DISPLAY Always Reads Empty
0 Always Reads Full
I 0 Reading Is Not Accurate - --
OIL PRESSURE Always Reads Maximum Pressure
DlSPLAV 0 Always Reads Zero Pressure
I 0 Is Not Accurate Replace
Cluster (See Section 8C)
Do Test
G
Do Test H I
Do Test I
Do Test K
Do Test J I
Do Test L I pp
(Continued on next page)