Pontiac Fiero 1988 Service Manual page 589

6E3-A-6 DRIVABILITY A N D EMISSIONS - F U E L INJECTION (PORT)
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 onboard 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 DISPLAYS 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
Idle / U p p e r R a d i a t o r Hose H o t / C l o s e d T h r o t t l e / Park o r N e u t r a l / C l o s e d L o o p / Ace, o f f
"SCAN" Position
Coolant Temp.
MAT Temp.
TPS
MAP
INT (Integrator)
BLM (Block Learn)
IAC
RPM
Units Displayed
c°
c°
Volts
Volts
Counts
Counts
Counts (steps)
RPM
Volts
Open/Closed
# of Degrees
M/Sec
0-100%
On-Off
Yes/No
On/Off
P/N and RDL
On/Off
MPH
Volts
Typical D a t a V a l u e
8 5 ° - 105°
10° - 60° (depends on underhood temp.)
. 4 - 1.25
1 - 2 (depends on Vac. & Baro pressure)
Varies
1 1 8 - 1 3 8
1 - 5 0
900 ± 75 RPM (depends on temperature)
. 1 - 1 and varies
Closed Loop (may go open w i t h extended idle)
Varies
. 7 - 2 . 0
0% (at idle)
Off
No (yes, w i t h A/C requested)
Off (on, w i t h A/C commanded on)
Park/Neutral (P/N)
Off/ (on, w i t h TCC commanded)
0
13.5-14.5
o
2
Open/Closed Loop
Spark Advance
BPW (base pulse w i d t h )
EGR Duty Cycle
EGR Vacuum Switch
A/C Request
A/C Clutch
P/N Switch
TCC
VSS
Battery
5-5-86
*7S3377-6E