GM Service Manual Online
For 1990-2009 cars only

The Engine Scan Tool Data List contains all engine-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 in Vehicle DTC Information 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:

Cooling/HVAC:: Cooling HVAC Data

Cruise/Traction: Cruise Control/Traction Data

Electrical Theft: Electrical/Theft Data

Eng: Engine data

EGR: Exhaust gas recirculation (EGR) data

EVAP: Evaporative emission (EVAP) data

FUEL TRIM: Fuel trim data

HO2S: Heated Oxygen Sensor (HO2S) data

Ignition: Ignition System data

IPC: IPC Data

Misfire: Misfire data

ODD: Output driver data

TAC Output: Throttle Actuator Control Data

Scan Tool Parameter

Data List

Units Displayed

Typical Data Value

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

A/C Disengage Reason

Cooling/HVAC

Swithed off/Pressure too high/pressure too low

Switched Off

A/C High side Pressure

Cooling/HVAC

PSI

varies

A/C High side Pressure

Cooling/HVAC

volts

varies

A/C Off for WOT

Cooling/HVAC

Yes/No

No

A/C Pressure Disable

Cooling/HVAC

Yes/No

No

A/C Relay Circuit Status

ODD

OK/Fault/Invalid State

OK

A/C Relay Circuit History

ODD, Cooling/HVAC

OK/Fault/Invalid State

OK

A/C Relay Command

Eng, Misfire, EGR, Cooling/HVAC, TAC

On/Off

Off

A/C Request Signal

Cooling/HVAC

Yes/No

No

Air Fuel Ratio

Eng, Fuel Trim, HO2S

Ratio

14.2:1-14.7:1

APP Indicated Angle

Cruise/Traction, Eng, EGR, EVAP, HO2S, Ignition, Misfire, TAC, Fuel Trim

Percent

0

APP Sensor 1

TAC

Volts

Varies

APP Sensor 1 Circuit Status

TAC

OK/Not OK

OK

APP Sensor 2

TAC

Volts

Varies

APP Sensor 2 Circuit Status

TAC

OK/Not OK

OK

APP Sensor 1

TAC

Percent

Varies

APP Sensor 2

TAC

Percent

Varies

APP Sensor 1 and 2

TAC

Agree/Disagree

Agree

BARO

Eng, EGR, EVAP, Fuel Trim, HO2S, Ignition

kPa

65-110 kPa

Catalytic Converter Protection Active

Fuel Trim, HO2S

Yes/No

No

CKP Sensor

Ignition Data

RPM

varies

CMP Sensor

Ignition

RPM

Varies

CMP Sensor Signal Present

Ignition, Misfire

Yes/No

Yes

Crank Request Signal

Electrical/Theft

Yes/No

No

Cruise On/Off switch

Cruise/Traction

On/Off

Off

Cruise Control Active

Cruise/Traction, IPC, TAC

Yes/No

No

Cruise Disengage 1-6 History

Cruise/Traction

engage/disengage

--

Cruise Mode Signal

Cruise/Traction

Volts

varies

Cruise Resume/Accel. Switch

Cruise/Traction

On/Off

Off

Cruise Set/Coast Switch

Cruise/Traction

On/Off

Off

Cycles of Misfire Data

Misfire

Counts

0-99

Cyl. 1-6 Injector Circuit Status

ODD

OK/Stuck Low (Open)/Stuck High

OK

Cylinder 1 and 4 IC Circuit Status

ODD

OK/Not OK

OK

Cylinder 2 and 5 IC Circuit Status

ODD

OK/Not OK

OK

Cylinder 3 and 6 IC Circuit Status

ODD

OK/Not OK

OK

Cylinder 1-6 Injector Circuit History

ODD

OK/Stuck Low (Open)/Stuck High

OK

Decel Fuel Cut-off

Eng, EGR, Fuel Trim, HO2S

Active/Inactive

Inactive

Desired EGR Position

EGR, Misfire

Percent

0

Desired Idle Speed

Cruise/Traction, Eng, EVAP, TAC

RPM

Varies

Driver Module 1 Status

ODD

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

Enabled

Driver Module 2 Status

ODD

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

Enabled

Driver Module 3 Status

ODD

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

Enabled

EC Ignition Relay Circuit Status

ODD

OK/ Fault/ Invalid State

OK

EC Ignition Relay Circuit History

Electrical Theft, ODD

OK/ Fault/ Invalid State

OK

ECT Sensor

Cooling/HVAC, Eng, EGR, EVAP, HO2S, IPC, Ignition, Misfire, Fuel Trim, TAC

°C/°F

Varies

EGR Flow Test Count

EGR

Counts

0

EGR Learned Minimum Position

EGR

Volts

0.14-1.0

EGR Position Sensor

Eng, EGR, Misfire

Percent

0%

EGR Position Sensor

EGR

Volts

0.6--0.7 volts

EGR Position Variance

EGR

Percent

0

EGR Solenoid Circuit History

ODD

OK/Open/Fault/ Invalid State

OK

EGR Solenoid Circuit Status

ODD

OK/Fault/ Invalid State

OK

EGR Solenoid Command

EGR

Percent

0

Engine Hot Lamp Command

Cooling/HVAC

On/Off

Off

Engine Load

Cooling/HVAC, Eng, Misfire, Fuel Trim, EVAP, EGR, HO2S, Ignition, TAC

Percent

Varies

Engine Oil Life Remaining

IPC

Percent

Varies

Engine Oil Pressure Switch

Eng, IPC

Low/OK

OK

Engine Run Time

Cruise/Traction, Cooling/HVAC, Eng, EVAP, Misfire, Fuel Trim, EGR, HO2S, Ignition, TAC, ODD

Hr: Min: Sec

Varies

Engine Speed

Cooling/HVAC, Cruise/TractionEng, EGR, Electrical/Theft, EVAP, Fuel Trim, HO2S, Ignition, IPC, Misfire, TAC

RPM

Varies

EVAP Fault History

EVAP

Fault/No Fault

No Fault

EVAP Purge Solenoid Circuit History

ODD

OK/Open/Short

OK

EVAP Purge Solenoid Circuit Status

ODD

OK/Open/Short

OK

EVAP Purge Solenoid Command

Eng, EVAP, Fuel Trim, HO2S

Percent

Varies

EVAP Vent Solenoid Circuit History

ODD

OK/Open/Short

OK

EVAP Vent Solenoid Circuit Status

ODD

OK/Open/Short

OK

EVAP Vent Solenoid Command

Eng, EVAP

Venting/Not Venting

Venting

FC Relay 1 Circuit History

Cooling/HVAC, ODD

OK/Fault/Invalid State

OK

FC Relay 1 Command

Cooling/HVAC

On/Off

Off

FC Relay 1 Circuit Status

ODD

OK/Fault/Invalid State

OK

FC Relay 2 and 3 Circuit History

Cooling/HVAC, ODD

OK/Fault/Invalid State

OK

FC Relay 2 and 3 Circuit Status

ODD

OK/Fault/Invalid State

OK

FC Relay 2 and 3 Command

Cooling/HVAC

On/Off

Off

Fuel Level Sensor

EVAP, IPC

Volts

Varies

Fuel Pump Relay Circuit History

ODD

OK/Fault/Invalid State

OK

Fuel Pump Relay Circuit Status

ODD

OK/Fault/Invalid State

OK

Fuel Pump Relay Command

Eng

On/Off

On

Fuel Tank Level Remaining

EVAP, IPC

Percent

0-104

Fuel Tank Pressure Sensor

Eng, EVAP

mm Hg/in H2O

Varies

Fuel Tank Pressure Sensor

EVAP

Volts

Varies

Fuel Trim Cell

EVAP, Eng, Fuel Trim

0-4

0

Fuel Trim Learn

Eng, EVAP, Fuel Trim

Enabled/Disabled

Enabled

Generator L-Terminal Signal Command

Electrical/Theft

On/Off

On

Generator Lamp Command

IPC Data, Electrical/Theft

On/Off

Off

HO2S 1

EVAP, Eng, Fuel Trim, HO2S

millivolts

0-1000 and Varying

HO2S 1 Ready

HO2S

Yes/No

Yes

HO2S 2

Eng, Fuel Trim, HO2S

millivolts

0-1000 and Varying

HO2S 1 Heater Command

HO2S

On/Off

On

HO2S 2 Heater Command

HO2S

On/Off

On

HO2S 1 Heater

HO2S

Amps

Varies

HO2S 2 Heater

HO2S

Amps

Varies

HO2S 1 Heater Circuit History

ODD

OK/Fault/ Invalid State

OK

HO2S 2 Heaster Circuit History

ODD

OK/Fault/ Invalid State

OK

HO2S 1 Heater Circuit Status

ODD

OK/Fault/ Invalid State

OK

HO2S 2 Heater Circuit Status

ODD

OK/Fault/ Invalid State

OK

Hot Open Loop

Cooling/HVAC, Fuel Trim, HO2S

Active/Inactive

Inactive

IAT Sensor

Cooling/HVAC, Eng, EVAP, EGR, Fuel Trim, HO2S, Ignition, Misfire, TAC

°C/°F

Varies

Ignition 1 Signal

Cooling/HVAC, Cruise/Traction, Electical/Theft, EVAP, Eng, EGR, Fuel Trim, HO2S, Ignition, IPC, Misfire, TAC

Volts

12.6 volts or more (varies)

Ignition Off Time

EVAP, Eng

Minutes/ Varies

Varies

Initial Brake Apply Signal

TAC

Released/ Applied

Released

Injector PWM

Fuel Trim, HO2S, Misfire

milliseconds

Varies

Knock Retard

EGR, Ignition

Degrees

0

KS Activity

Ignition

Yes/No

No

Long Term FT

Eng, EVAP, Fuel Trim, HO2S

Percent

-10 to +10%

Long Term FT Average

Fuel Trim

Percent

varies

Loop Status

Eng, Fuel Trim, EVAP, HO2S

Open/Closed

Closed

MAF Sensor

Eng, EGR, Misfire, EVAP, Fuel Trim, HO2S, Ignition, TAC

g/s

3-6 (Varies with altitude)

MAF Sensor

EVAP, Fuel Trim, HO2S, Misfire, TAC

Hz

1,200-3,000 (Depends on altitude)

MAP Sensor

Eng, EGR, Fuel Trim, HO2S, Misfire, TAC

Volts

0.4-2.0 Volts

MAP Sensor

Eng, EVAP, Fuel Trim, HO2S, Ignition, Misfire, EGR, TAC

kPa

20-48 kPa (Varies with altitude)

MIL Circuit History

IPC, ODD

OK/Fault/Invalid State

OK

MIL Command

EVAP, Eng, EGR, Ignition, IPC

On/Off

Off

MIL Circuit Status

ODD

OK/Fault/Invalid State

OK

Mileage Since DTC Cleared

Eng

km/h /mph

Varies

Misfire Current Cyl. 1-6

Misfire

Counts

0

Misfire History Cyl. 1-6

Misfire

Counts

0

Moderate Brake Apply Signal

TAC

Applied/Released

Released

Number of DTCs

Eng

Number

0

PCM Reset

EGR, Eng, EVAP, Ign, ODD

Yes/No

No

Power Enrichment

Eng, Fuel Trim, HO2S, Misfire

Active/Inactive

Inactive

Reduced Engine Power

HO2S, TAC

Active/Inactive

Inactive

Short Term FT

Eng, EVAP, Fuel Trim, HO2S,

Percent

-10 to +10%

Spark

Cooling/HVAC, Cruise/Traction, Eng, Misfire, Fuel Trim, HO2S, Ignition

Degrees

16° (varies)

Start Up ECT

Cooling/HVAC, EVAP, Fuel Trim, HO2S

°C/°F

Varies

Start Up IAT

EVAP, Fuel Trim, HO2S

°C/°F

Varies

Starter Relay Circuit Status

ODD

OK/ Fault

OK

Starter Relay Circuit History

Electrical/Theft, ODD

OK/ Fault/ Invalid State

OK

Starter Relay Command

Electrical/Theft

On/Off

Off

Stop Lamp Pedal Switch

Cruise/Traction, Eng, Electrical/Theft, TAC

Released/Applied

Released

Stop Lamp Switch Signal

Electrical/Theft, Cruise/Traction, TAC

volts

Varies

TAC/PCM Communications Signal

Cruise/Traction, TAC

OK/ Fault

OK

TAC Stop Lamp Pedal Switch

Cruise/Traction, Electrical/Theft, TAC

Applied/Released

Released

TAC Vehicle Speed Signal

TAC

OK/Fault

OK

TCS Delivered Torque Circuit Status

ODD

OK/ Fault

OK

Torque Request Signal

Cruise/Traction, TAC

Percent

100%

Torque Delivered Signal

TAC

Percent

75%

Total Misfire Count

Misfire

1-255

0

TP Desired Angle

Cruise/Traction, TAC

Percent

Varies

TP Indicated Angle

Cruise/Traction, EGR, Eng , Fuel Trim, HO2S, Ignition, EVAP, Misfire, TAC

Percent

%

TP Sensor 1

TAC

Percent

Varies

TP Sensor 1

TAC

Volts

Varies

TP Sensors 1 and 2

TAC

Agree/ Disagree

Agree

TP Sensor 1 Circuit Status

TAC

OK/Not OK

OK

TP Sensor 2

TAC

Percent

Varies

TP Sensor 2

TAC

Volts

Varies

TP Sensor 2 Circuit Status

TAC

OK/Not OK

OK

Traction Control Status

Cruise/Traction, TAC

Active/Inactive

Inactive

TWC Temperature Calculated

Fuel Trim, Misfire

°C/°F

varies

Vehicle Security Status

Electrical/Theft

OK/Not OK

OK

Vehicle Speed Circuit History

ODD

OK/ Fault/ Invalid State

OK

Vehicle Speed Circuit Status

ODD

OK/ Fault/ Invalid State

OK

Vehicle Speed Sensor

Cooling HVAC, Cruise/Traction, Eng, EGR, EVAP, HO2S, Ignition, IPC, Fuel Trim, Misfire, TAC

mph/ km/h

0

Warm-ups w/o Emission Faults

Eng

1-10

varies

Warm-ups w/o Non-Emission Faults

Eng

1-10

varies