GM Service Manual Online
For 1990-2009 cars only

The Engine Scan Tool Data List contains all engine controls-related parameters that are available on the scan tool. The list is arranged in alphabetical order. A given parameter may appear in any one of the data lists, and in some cases may appear more than once, or in more than one data list in order to group certain related parameters together.

Use the Engine Scan Tool Data List only after the following is determined:

    • The Diagnostic System Check - Vehicle is completed.
    • No diagnostic trouble codes (DTCs).
    • On-board diagnostics are functioning properly

The scan tool values from a properly running engine may be used for comparison with the engine you are diagnosing. The Engine Scan Tool Data List represents values that would be seen on a normally running engine.

Important: A scan tool that displays faulty data should not be used. The scan tool concern should be reported to the manufacturer. Use of a faulty scan tool can result in misdiagnosis and unnecessary parts replacement.

Only the parameters listed below are referenced in this service manual for use in diagnosis. If all values are within the typical range described below, refer to Symptoms - Engine Controls for diagnosis.

The column labeled Data List indicates where a parameter can be located on the scan tool. Refer to the scan tool operating manual for the exact locations of the data lists. The following is a description of each term listed:

Eng: Engine data

EGR: Exhaust gas recirculation (EGR) data

EVAP: Evaporative emission (EVAP) data

FT: Fuel trim data

HO2S: Heated Oxygen Sensor (HO2S) data

Ign: Ignition System data

I/M: I/M data

Misfire: Misfire data

ODD: Output Driver data

TAC: Throttle Actuator Control Data

Scan Tool Parameter

Data List

Units Displayed

Typical Data Value

Operating Conditions: Engine Idling/Radiator Hose Hot/Closed Throttle/Park or Neutral/Closed Loop/Accessories Off/Brake Pedal Released

APP Indicated Angle

Eng, EGR, EVAP, FT, HO2S, Ign, Misfire, TAC

%

0

APP Sensor 1

TAC

Volts

0.86

APP Sensor 1

TAC

%

0

APP Sensor 1 and 2

TAC

Agree/Disagree

Agree

APP Sensor 1 Circuit Status

TAC

OK/Fault

OK

APP Sensor 2

TAC

Volts

0.88

APP Sensor 2

TAC

%

0

APP Sensor 2 Circuit Status

TAC

OK/Fault

OK

BARO

Eng, EGR, EVAP, FT, HO2S, Ign, I/M

kPa

60-104 (varies with altitude)

Catalyst Monitor Complete This Ignition

I/M

Yes/No

Varies

Catalyst Monitor Enabled This Ignition

I/M

Yes/No

Yes

Catalytic Converter Protection Active

FT, HO2S

Yes/No

No

CKP Sensor

Ign

RPM

700-750

Cmmd. A/F Equivalence Ratio

Eng, FT, HO2S

:1

1.0

CMP Sensor

Ign, Misfire

RPM

700-750

CMP Sensor Signal Present

Ign

Yes/No

Yes

Cycles of Misfire Data

Misfire

Counts

0-100 incrementing

Cylinder 1 and 4 IC Circuit Status

ODD

OK/Fault

OK

Cylinder 1 Injector Circuit History

ODD

OK/Open/Short/Invalid

OK

Cylinder 1 Injector Circuit Status

ODD

OK/Fault

OK

Cylinder 2 and 5 IC Circuit Status

ODD

OK/Fault

OK

Cylinder 2 Injector Circuit History

ODD

OK/Open/Short/Invalid

OK

Cylinder 2 Injector Circuit Status

ODD

OK/Fault

OK

Cylinder 3 and 6 IC Circuit Status

ODD

OK/Fault

OK

Cylinder 3 Injector Circuit History

ODD

OK/Open/Short/Invalid

OK

Cylinder 3 Injector Circuit Status

ODD

OK/Fault

OK

Cylinder 4 Injector Circuit History

ODD

OK/Open/Short/Invalid

OK

Cylinder 4 Injector Circuit Status

ODD

OK/Fault

OK

Cylinder 5 Injector Circuit History

ODD

OK/Open/Short/Invalid

OK

Cylinder 5 Injector Circuit Status

ODD

OK/Fault

OK

Cylinder 6 Injector Circuit History

ODD

OK/Open/Short/Invalid

OK

Cylinder 6 Injector Circuit Status

ODD

OK/Fault

OK

Decel. Fuel Cutoff

Eng, EGR, FT, HO2S

Active/Inactive

Inactive

Desired EGR Position

EGR

%

0

Desired Idle Speed

Eng, EVAP, TAC

RPM

720

Distance Since DTC Cleared

Eng

km/miles

Varies

Driver 1 Module Status

ODD

Enabled/Off-High Volts/Off-High Temp/Invalid

Enabled

Driver 2 Module Status

ODD

Enabled/Off-High Volts/Off-High Temp/Invalid

Enabled

Driver 3 Module Status

ODD

Enabled/Off-High Temp

Enabled

EC Ignition Relay Circuit History

ODD

OK/Open/Short/Invalid

OK

EC Ignition Relay Circuit Status

ODD

OK/Fault/Invalid

OK

ECT Sensor

Eng, EGR, EVAP, FT, HO2S, Ign, Misfire, TAC, I/M

°C/°F

99/210

EGR Flow Test Count

EGR

Counts

0-12

EGR Learned Minimum Position

EGR

Volts

0.14-1.0

EGR Monitor Complete This Ignition

I/M

Yes/No

Varies

EGR Monitor Enabled This Ignition

I/M

Yes/No

Yes

EGR Position Sensor

Eng, EGR, Misfire

%

0

EGR Position Sensor

EGR

Volts

0.71

EGR Position Variance

EGR

%

-100

EGR Solenoid Circuit history

ODD

OK/Open/Stuck Low/Stuck High/High Voltage/High Temp/Invalid

OK

EGR Solenoid Circuit Status

ODD

OK/Fault/Invalid

OK

EGR Solenoid Command

EGR

%

0

Engine Load

Eng, EGR, EVAP, FT, HO2S, Ign, Misfire, TAC

%

Varies

Engine Run Time

Eng, EGR, EVAP, FT, HO2S, Ign, I/M, Misfire, TAC, ODD

Hr:Min:Sec

Varies

Engine Speed

Eng, EGR, EVAP, FT, HO2S, Ign, Misfire, TAC

RPM

700-750

Engine Speed Circuit Status

ODD

OK/Fault/Invalid

OK

EVAP Fault History

EVAP

No Fault/Excess Vacuum/Purge Valve Leak/ Small Leak/Weak Vacuum/No Test Result

No Fault

EVAP Monitor Complete This Ignition

I/M

Yes/No

Varies

EVAP Monitor Enabled This Ignition

I/M

Yes/No

No

EVAP Purge Solenoid Circuit History

ODD

OK/Open/Short/Invalid

OK

EVAP Purge Solenoid Circuit Status

ODD

OK/Fault/Invalid

OK

EVAP Purge Solenoid Command

Eng, EVAP, FT, HO2S

%

10-15

EVAP Vent Solenoid Circuit History

ODD

OK/Open/Short/Invalid

OK

EVAP Vent Solenoid Circuit Status

ODD

OK/Fault/Invalid

OK

EVAP Vent Solenoid Command

Eng, EVAP

Venting/Not Venting

Venting

Fuel Level Sensor

EVAP

Volts

Varies

Fuel Pump Relay Circuit History

ODD

OK/Open/Stuck Low/Stuck High/High Voltage/High Temp/Invalid

OK

Fuel Pump Relay Circuit Status

ODD

OK/Fault/Invalid

OK

Fuel Pump Relay Command

Eng

On/Off

On

Fuel Tank Level Remaining

EVAP, FT, Misfire, I/M

%

Varies

Fuel Tank Pressure Sensor

Eng, EVAP

mm Hg/in H2O

-19.8 to +12.52/-10.5 to +6.17

Fuel Tank Pressure Sensor

EVAP

Volts

0.2-4.0

Fuel Trim Cell

Eng, FT

Cell

0

Fuel Trim Learn

FT

Enabled/Disabled

Enabled

HO2S 1

Eng, EVAP, FT, HO2S

mV

0-1,000

HO2S 2

Eng, FT, HO2S

mV

50-850

HO2S 1 Heater Command

HO2S

On/Off

On

HO2S 2 Heater Command

HO2S

On/Off

On

HO2S 1 Heater

HO2S

amps

0.50-1.00

HO2S 1 Heater Circuit History

ODD

OK/Open/Short/Invalid

OK

HO2S 1 Heater Circuit Status

ODD

OK/Fault/Invalid

OK

HO2S 1 Ready

FT, HO2S

Yes/No

Yes

HO2S 2 Heater

HO2S

amps

0.50-1.00

HO2S 2 Heater Circuit History

ODD

OK/Open/Short/Invalid

OK

HO2S 2 Heater Circuit Status

ODD

OK/Fault/Invalid

OK

HO2S Heater Monitor Complete This Ignition

I/M

Yes/No

Varies

HO2S Heater Monitor Enabled This Ignition

I/M

Yes/No

Varies

HO2S/O2S Monitor Complete This Ignition

I/M

Yes/No

Varies

HO2S/O2S Monitor Enabled This Ignition

I/M

Yes/No

Varies

HOT Open Loop

FT, HO2S

Active/Inactive

Inactive

IAT Sensor

Eng, EGR, EVAP, FT, HO2S, Ign, I/M, Misfire, TAC

°C/°F

Varies

Ignition 1 Signal

Eng, EGR, EVAP, FT, HO2S, Ign, I/M, Misfire

Volts

12-14.5

Ignition Mode

Ign

IC/Bypass

IC

Ignition Off Time

Eng, EVAP, I/M

min

Varies

Injector PWM

Eng, FT, HO2S, Misfire

ms

1.85-2.05

Knock Retard

EGR, Ign

degrees

0

KS Active Counter

Ign

Yes/No

No

Long Term FT

Eng, EVAP, FT, HO2S

%

0

Loop Status

Eng, EVAP, FT, HO2S

Open/Closed

Closed

MAF Sensor

Eng, EGR, EVAP, FT, HO2S, Ign, Misfire, TAC

g/s

3-6 (varies with altitude)

MAF Sensor

Eng

Hz

1,200-1,300 (varies with altitude)

MAP Sensor

Eng, EGR, EVAP, FT, HO2S, Ign, Misfire, TAC

kPa

20-48 (varies with altitude)

MAP Sensor

Eng

Volts

0.4-2.0 (varies with altitude)

MIL Circuit History

ODD

OK/Open/Short/Invalid

OK

MIL Circuit Status

ODD

OK/Fault/Invalid

OK

MIL Command

Eng, I/M

On/Off

Off

Misfire Current Cyl. 1

Misfire

Counts

0

Misfire Current Cyl. 2

Misfire

Counts

0

Misfire Current Cyl. 3

Misfire

Counts

0

Misfire Current Cyl. 4

Misfire

Counts

0

Misfire Current Cyl. 5

Misfire

Counts

0

Misfire Current Cyl. 6

Misfire

Counts

0

Misfire History Cyl. 1

Misfire

Counts

0

Misfire History Cyl. 2

Misfire

Counts

0

Misfire History Cyl. 3

Misfire

Counts

0

Misfire History Cyl. 4

Misfire

Counts

0

Misfire History Cyl. 5

Misfire

Counts

0

Misfire History Cyl. 6

Misfire

Counts

0

Power Enrichment

Eng, FT, HO2S, Misfire

Active/Inactive

Inactive

Short Term FT

Eng, EVAP, FT, HO2S

%

0

Spark

Eng, FT, HO2S, Ign, Misfire

degrees

18-24

Start-up ECT

EVAP, HO2S, I/M

°C/°F

Varies

Start-up IAT

EVAP, HO2S, I/M

°C/°F

Varies

TAC Stoplamp Pedal Switch

TAC

Released/Applied

Released

TAC Vehicle Speed Signal

TAC

OK/Fault

OK

TAC/PCM Communication Signal

TAC

OK/Fault

OK

Total Misfire

Misfire

Counts

0

TP Desired Angle

TAC

%

3

TP Indicated Angle

Eng, EGR, EVAP, FT, HO2S, Ign, Misfire, TAC

%

3

TP Sensor 1

TAC

Volts

0.69

TP Sensor 1

TAC

%

3

TP Sensor 1 Circuit Status

TAC

OK/Fault

OK

TP Sensor 2

TAC

Volts

0.69

TP Sensor 2

TAC

%

3

TP Sensor 2 Circuit Status

TAC

OK/Fault

OK

TP Sensors 1 and 2

TAC

Agree/Disagree

Agree

TWC Temperature Calculated

FT, Misfire

°C/°F

Varies

Vehicle Speed Sensor

Eng, EGR, EVAP, FT, HO2S, Ign, I/M, Misfire, TAC

km/h /mph

0

Warm-ups Since DTC Cleared

Eng

Counts

Varies

Warm-ups w/o Emission Faults

Eng

Counts

Varies

Warm-ups w/o Non-Emission Faults

Eng

Counts

Varies