Scan Tool Data List

If after completing the on-board diagnostic system check and finding the on-board diagnostics functioning properly and no diagnostic trouble codes displayed "Typical Scan Values" for the appropriate engine may be used for comparison. 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 display.

CAUTI0N: If a scan tool displays any data known to be inaccurate or faulty, the tool should not be used for diagnosis. Using a faulty or incompatible scan tool can result in misdiagnosis and unnecessary parts replacement.

Only the parameters listed below are used in this manual for diagnosis. If a scan tool reads other parameters, the values are not recommended by General Motors for use in diagnosis.

NOTE: If all values are within the range illustrated, refer to DIAGNOSIS BY SYMPTOM. Testing and Inspection

NOTE: Be sure the following conditions are met when recording actual data values.

^ Engine at normal operating temperature (upper radiator hose hot)
^ Engine idling at closed throttle
^ Transmission gear selector in "Park" or "Neutral" position
^ System operating in "Closed Loop"
^ All Accessories and A/C turned "OFF"
^ Brake Not Applied

TYPICAL SCAN DATA VALUES

TECH-1 PARAMETER UNITS TYPICAL DATA VALUE

Engine Speed RPM 650-750
Desired Idle RPM 675
Eng Cool Temp °C°F Varies 85°-105°C (185°-220°F)
Intake Air Temp °C °F Varies with air temp.
Throt Position Volts .20-.74
Throttle Angle Percent 0%
Mass Air Flow Gm/Sec 4.9 (varies)
Calc Eng Load Counts 70-80
HO2S mV (millivolts) Varies (100-900)
Loop Status Open Loop/Closed Loop Closed Loop
HO2S Cross Cnts Counts Varies
Rich/Lean Status Rich/Lean Rich/Lean Changing Constantly
Spark Advance Degrees 16° (Varies)
ST. Fuel Trim Counts 95-140*
L.T. Fuel Trim Counts 95-138*
Fuel Trim Cell Cell# 0
Knock Retard Degrees 0°
Knock Signal Yes/No No
Idle Air Control Counts 16-20
Park/Neutral Pos P-N/R-DL P-N
MPH Km/h mph, Km/h 0, 0
TCC Mode On/Apply/Off/Release Off
TCC Duty Cycle Percent 0%
TCC Slip RPM +254
N/V Ratio Counts 0
Current Weak Cyl Cylinder #/None None
Driver Select Sw (VIN-1 only) Normal/Sporty/N/A Normal
Boost Duty Cycle (VIN-1 only) Percent 100%
Cam/Crank Error Counts 0-2 (Varies)
Trans Fluid Temp C°/F° Varies
Fuel Evap Purge Percent Varies
System Voltage Volts 13.5V (varies)
A/C Request Yes/No No
A/C Clutch On/Off Off
Fan 1 Fan 2 On/Off Off
A/C Head Press. OK/High OK
Actual EGR Pos Percent 0%
Desired EGR Pos Percent 0%
EGR Pintle Pos Volts 0-1V
C/C Brake Switch Applied/Released Released (Applied if C/C ON-OFF Switch is "OFF.")
TCC Brake Switch Applied/Released Released
C/C Set Speed mph. Km/h 0, 0
MPH, Km/h mph, Km/h 0, 0
Actual Servo Pos. Percent 0%
Desired Servo Pos. Percent 0%
Cruise Mode Off/Disengaged/Stand by/ Off
Cruise/Resume/Accelerate/Coast
Raw Servo Pos. Counts Approx. 15-85 and Steady
C/C Brake Switch Applied/Released Released (Applied if C/C
ON-OFF Switch is "OFF.")
C/C On/Off Sw On/Off Off
C/C Res/Accel Sw On/Off Off
C/C Set/Coast Sw On/Off Off
C/C Vacuum So On/Off Off
C/C Vent Sol On/Off Off
Shift A Sol On/Off On
Shift B Sol On/Off On
PRNDL P High/Low Low
PRNDL A High/Low Low
PRNDL B High/Low High
PRNDL C High/Low High
Trans Range Switch Low/Drive 2/Drive 3/Drive 4/ Park
Neutral/Reverse/Park
Commanded Gear First/Second/Third/Fourth 1st
P/N Yes/No Yes
2nd Actual Yes/No No
3rd Actual Yes/No No
4th Actual Yes/No No
QDM 1 High/Low Low
QDM 2 High/Low Low
QDM 4 High/Low Low
PASS-KEY ii Fuel (C/H only) Enabled/Disabled Enabled
Calibration ID Prom ID # Internal l.D. only
Time From Start Minutes Varies

* A poor PCM ground at the ignition mounting bracket to engine, could cause short term fuel trim and long term fuel trim to read around 150, make a careful physical inspection of this critical connection.