1988 PONTIAC FIERO Service Repair Manual

6E3-A-4 2.8L (VIN S) DRIVEABILITY AND EMISSIONS
ECMIIGN
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1
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PRIMARY COIL I
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FUEL PUMP
CONNECTOR FUEL
FUEL PUMP SIGNAL

DRIVEABILITY AND EMISSIONS 2.8L (VIN S) 6E3-A-5
ECM
BRAKE SWITC
BACK
VIEW OF
AIR DIVERT SOLENOID
MANUALITRANS
IGNITION 12V
TANMIHT 250 ALTERNATOR
Figure A1-4 - Wiring Diagram 2.8L "F" Series (3 of 3)

DRIVEABILITY AND EMISSIONS f.8L (VIM 9) 6E3-A-7
BLANK

DIAGNOSTIC CIRCUIT CHECK
The diagnostic circuit check is an organized approach to identifying a problem created by an electronic
engine control system malfunction. It
must be the starting point for any driveability complaint diagnosis,
because it directs the service technician to the next logical step in diagnosing the complaint.
The "Scan Data" listed in the table may be used for comparison, after completing the diagnostic circuit check
and finding the on-board diagnostics functioning properly and no trouble codes displayed. The "Typical Values"
are an average of display values recorded from normally operating vehicles and are intended to represent what a
normally functioning system would typically display.
A "SCAN" TOOL THAT BiSPLAYS FAULTY DATA SHOULD NOT BE USED, AND THE PROBLEM
SHOULD BE REPORTED
TO THE MANUFACTURER. THE USE OF A FAULTY "SCAN" CAN RESULT
IN MISDIAGNOSIS AND UNNECESSARY PARTS REPLACEMENT.
Only the parameters listed below are used in this manual for diagnosis. If a "Scan" reads other parameters,
the values are not recommended by General Motors for use in diagnosis. For more description on the values and
use of the "Scan" to diagnosis
ECM inputs, refer to the applicable diagnosis section in Section "C". If all values
are within the range illustrated, refer to symptoms in Section
"B".
""SCAN" DATA
Coolant Temp. CO 85" - 105"
MAT Temp. C0 10" - 60" (depends on underhood temp.)
TPS
volts 0.35 - 0.67
MAF
gmlsec 4-7
INT (Integrator) Counts Varies
BLM (Block Learn) Counts 118- 138
IAC Counts (steps) 5-50
rPm rPm 1000 ? 50 rpm (depends on temperature)
0 2 volts .I - 1 and varies
OpenIClosed Loop OpenIClosed Closed Loop (may go open with extended idle)
Spark Advance
# of Degrees Varies
BPW (base pulse width) MISec .7 - 2.0
EGR Duty Cycle 0-
100% 0%
(at idle)
NC Request YesINo No (yes, with NC requested)
4th gear
YesINo No (yes, when in 4th gear)
NC Clutch ONIOFF OFF (ON, with NC commanded ON)
PIN Switch PIN
and
RBL ParkINeutral (PIN)
Power Steering Pressure Switch
NormalIHI pressure Normal
TCC
ONIOFF OFF1 (ON, with TCC commanded)
VSS mph 0

DRIVEABILITY AND EMISSIONS 2.8L (VlN S) 6E3-A-9

6E3-A-"I 2.8L (VlN S) DRIVEABILITY AND EMlSSlONS
TO OIL PRESS. SW.
&FUEL PUMP RELAY
FUSE
81 HOLDER BATTERY 12 V .. m.. . n.
. . . . . . . . FUSIBLE LINK
439 PNWBLK
419 BRNNVHT
SERIAL
DATA
451
WHTJBLK
450 BLKNVHT
ALDL CONNECTOR
NO "SERVICE ENGlNE SOON" "LIGHT
2.8b (VIM 5) 'T" "SERIES (PORT)
Circuit Description:
There should always be a steady "Service Engine Soon" light when the ignition is "ON" and engine stopped.
Battery is supplied directly to the light bulb. The electronic control module
(ECNI) will control the light and
turn it "ON" by providing a ground path through CKT 419 to the ECM.
Test Description: Numbers below refer to circled
numbers on the diagnostic chart.
1. If the fuse in holder is blown refer to facing page of
Code
54 for complete circuit.
2. Using a test light connected to 12 volts probe each
of the system ground circuits to be sure a good
ground is present. See ECM terminal end view in
front of this section for
ECM pin locations of
ground circuits.
Diagnostic Aids:
Engine runs OK, check:
@ Faulty light bulb.
@ CKT 419 open.
@ Gage fuse blown.
This will result in no oil or
generator lights, seat belt reminder, etc. Engine
cranks but will not run.
@ Continuous battery - fuse or fusible link open.
@ ECM ignition fuse open.
@ Battery CKT 340 to ECM open.
@ Ignition CKT 439 to ECM open.
e Poor connection to ECM.
Solenoids and relays are turned "ON"
and "OFF"
by the ECM, using internal electronic switches called
"drivers". Each driver is part of a group of four called
"Quad-Drivers". Failure of one driver can damage
any other driver in the set. Solenoid and relay coil
resistance must measure more than 20 ohms. Less
resistance will cause early failure of the ECM
"driver".
Before replacing ECM, be sure to check the coil
resistance of all solenoids and relays controlled by the
ECM. See ECM wiring diagram for the
solenoid(s)
and relay(s) and the coil terminal identification.

DRIVEABILITY AND EMISSIONS 2.8L (VIN 5) 6E3-A-l l
CHART A-1
CLEAR CODES AND CONFIRM "CLOSED LOOP " OPERATION AND NO "SERVICE ENGINE SOON" LIGHT.
DISCONNECT
ECM CONNECTORS. BATTERY
FUSE (IN HOLDER)
IGNITION "ON".
PROBE
CUT 419, WITH TEST LIGHT
TO GROUND.
- GAGE FUSE. SHORT TO GROUND IN
- FAULTY BULB. @ PROBE CKT 340 & 439 CIRCUIT THAT HAD A
- OPEN CUT 419. WITH TEST LIGHT TO
- CKT 419 SHORTED TO
REPAIR OPEN IN
GROUNDS OR ECM. CIRCUIT THAT DID NOT
SEE QUAD DRIVER
CHECK (CHART
C-1).