Pontiac Fiero 1988 Service Manual page 432

DRIVEABILITY AND EMISSIONS - FUEL INJECTION 6E-5
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TERMINAL IDENTIFICATION
[A~1 GROUND [EJJ SERIAL DATA
(SEE SPECIAL TOOLS)
[FH T.CC (IF USED)
FUEL PUMP (IF USED)
DIAGNOSTIC TERMINAL
A.I.R. (IF USED)
SERVICE ENGINE
SOON LAMP-IF USED
3 29-86
*6S 2615-6E
SERIAL DATA (IF USED)
(SEE SPECIAL TOOLS)
Figure 2 - ALDL Connector
are stored, Code 12 will continue to flash until the
Diagnostic terminal is ungrounded.
Codes can only be obtained with the engine
stopped. Grounding the Diagnostic terminal with the
engine running gives the "field service mode".
2. Display any stored trouble codes by flashing the
"Service Engine Soon" light. Each code will be
flashed three times, then Code 12 will be flashed
again.
If a trouble code is displayed, the memory is
cleared, then the engine is run to see if the code is
a "hard" or "intermittent" failure. If it is a "hard"
failure, a Diagnostic Code chart is used to find the
problem. If it is an intermittent failure, the charts
are not used. Diagnostic aids are usually included
on the facing page. Section "B" also covers the
topic of "Intermittents". A physical inspection of
the applicable system most often will resolve the
problem.
3. Energize all ECM controlled relays and solenoids
except fuel pump relay .
4. The IAC valve on most models also moves to the
fully extended position.
Field Service Mode
If the Diagnostic terminal is grounded with the
engine running, the system will enter the Field
Service mode. In this mode, the "Service Engine
Soon" light will show whether the system is in "Open"
or "Closed Loop".
In "Open Loop" the "Service Engine Soon" light
flashes two and one-half times per second.
In "Closed Loop", the light flashes once per second:
Also, in "Closed Loop", the light will stay OUT most of
the time if the system is too lean. It will stay "ON"
most of the time if the system is too rich.
While the system is in Field Service Mode, the
ECM will be in the following mode:
1. New trouble codes cannot be stored in the ECM.
2. The "Closed Loop" timer is bypassed.
Clearing Trouble Codes
When the ECM sets a trouble code, the "Service
Engine Soon" light will come "ON" and a trouble code
will be stored in memory. If the problem is
intermittent, the light will go out 10 seconds after the
fault goes away. However, the trouble code will stay
in the ECM memory until the battery voltage to the
ECM is removed. Removing battery voltage for 30
seconds will clear all stored trouble codes.
Trouble Codes should be cleared after repairs have
been completed. Also, some diagnostic charts will tell
you to clear the codes before using the chart. This
allows the ECM to set the code while going thru the
chart, which will help to find the cause of the problem
more quickly.
NOTICE:
To prevent ECM damage, the key must
be " O F F " when disconnecting or
reconnecting power to ECM (for
example battery cable, ECM pigtail,
ECM fuse, jumper cables, etc.).
ECM Learning Ability
The ECM has a "learning" ability which allows it
to make corrections for minor variations in the fuel
system to improve driveability. If the battery is
disconnected to clear diagnostic codes, or for repair,
the "learning" process has to begin all over again. A
change may be noted in the vehicle's performance. To
"teach" the vehicle, make sure the engine is at
operating temperature, and drive at part throttle,
with moderate acceleration and idle conditions, until
normal performance returns.
DRIVEABILITY AND EMISSIONS
SECTIONS 6E2 and 6 E 3 SUMMARY
The Driveability and Emissions sections are
subdivided into three sub-sections:
SECTION A : STARTING POINT AND CODE CHARTS
• Diagnostic circuit check (Starting Point)
• No-start and fuel system check charts
• Code Charts
SECTION B: SYMPTOMS
• Based on driveability symptoms, when no
codes, or intermittent codes, are stored.
SECTION C: COMPONENT SYSTEMS
• Circuit descriptions
• On-car service
• Functional check/Diagnosis charts