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:

    • Powertrain On-Board Diagnostic System Check is completed.
    • No Diagnostic Trouble Codes (DTCs) are active.
    • On-board diagnostics are functioning properly.

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 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 1: Engine Data 1 List

Eng 2: Engine Data 2 List

EGR: Exhaust Recirculation Valve Data

EVAP: Evaporative Emissions Data

Cat: Exhaust Catalyst Data

HO2S: Heated Oxygen Sensor Data

Misfire: Cylinder Misfire Data

Cruise: Cruise Control Data

TAC: Throttle Actuator Control Data

ODD: Output Driver 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

3X Crank Sensor

Misfire

RPM

Varies

18X Crank Sensor

Misfire

RPM

Varies

1-2 Sol.

ODD

OK/Fault/Invalid State

OK

2-3 Sol.

ODD

OK/Fault/Invalid State

OK

3-2 Downshift Sol.

ODD

OK/Fault/Invalid State

OK

A/C High Side Pressure

Eng 2

Volts

Varies

A/C Press Out of Range

Eng 2

Yes/No

No

A/C Relay

ODD

OK/Fault/Invalid State

OK

A/C Request

Eng 2, Cat, Misfire

Yes/No

No

Actual EGR Position

Eng 1, 2, EGR, Misfire

Percent

0

Air Fuel Ratio

Eng 1, Cat, HO2S

Ratio

14.2:1 - 14.7:1

APP Average

Eng 1, 2, EGR, Cat, HO2S, Cruise, TAC

Counts

Varies

APP Indicated Angle

Eng 1, 2, EGR, Cat, HO2S, Cruise, TAC

Percent

0

APP Sensor 1

TAC

Volts

0.8 - 1.0

APP Sensor 2

TAC

Volts

0.8 - 1.0

APP Sensor 3

TAC

Volts

0.8 - 1.0

APP Sensor 1 Angle

TAC

Percent

0

APP Sensor 2 Angle

TAC

Percent

0

APP Sensor 3 Angle

TAC

Percent

0

APP Sen. 1 and 2 Disagree

TAC

Yes/No

No

APP Sen. 1 and 3 Disagree

TAC

Yes/No

No

APP Sen. 2 and 3 Disagree

TAC

Yes/No

No

APP Sen. 1 Out of Range

TAC

Yes/No

No

APP Sen. 2 Out of Range

TAC

Yes/No

No

APP Sen. 3 Out of Range

TAC

Yes/No

No

BARO

Eng 1, 2, EGR, EVAP, Cat

kPa/Volts

65-110 kPa / 3.5-4.5 Volts

Brake Switch

Cruise, TAC

Applied/Released

Released

Cam Signal Present

Misfire

Yes/No

Yes

Clutch Anticipate Switch

Cruise (w/ Manual Transmission)

Applied/Released

Released

Commanded A/C

Eng 2, Cat, Misfire

On/Off

Off

Commanded Gen

Eng 1

On/Off

On

Cruise

Cruise, TAC

Engaged/Disengaged

Disengaged

Cruise Disengage Hist.1-6

Cruise

Cruise Control Diagnosis

Varies

Cruise Release Sw.

Cruise, TAC

Applied/Released

Released

Cruise Resume/Accel

Cruise, TAC

On/Off

Off

Cruise Set/Coast

Cruise, TAC

On/Off

Off

Cruise Switch

Cruise, TAC

On/Off

Off

Current Gear

Eng 1

Transmission Gear Position

1

Cyl. 1-6 Ckt. History

ODD

OK/Stuck Low (open)/Stuck High/Fault

OK

Cyl. 1-6 Ckt. Status

ODD

OK/Stuck Low (open)/Stuck High

OK

Decel Fuel Mode

Eng 1, 2, Cat, HO2S, Misfire, Cruise, TAC

Active/Inactive

Inactive

Desired EGR Position

Eng 1, 2, EGR, Misfire

Percent

0

Desired Idle Speed

Eng 1, 2, EVAP, Cruise, TAC

RPM

PCM Controlled (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

Driver Module 4 Status

ODD

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

Enabled

ECT

Eng 1, 2, EGR, EVAP, Cat, HO2S, Misfire

°C/°F

Varies

EGR Closed Val. Pintle

EGR

Volts

0.14-1.0

EGR Duty Cycle

EGR

Percent

0

EGR Feedback

EGR

Volts

0.14-1.0

EGR Flow Test Count

EGR

Counts

0-10

EGR Position Error

EGR

Percent

0-100

Engine Load

Eng 1, 2, Cat, Misfire, Cruise, TAC

Percent

2-5

Engine Run Time

Engine 1, 2, EVAP, Cat, Cruise, TAC

Hr: Min: Sec

Varies

Engine Speed

Eng 1, 2, EGR, EVAP, Cat, HO2S, Misfire, Cruise, TAC

RPM

Varies

EVAP Canister Purge

EVAP, HO2S

Percent

Low and Varying

EVAP Fault History

EVAP

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

No Fault

EVAP Purge Sol.

ODD

OK/Fault/Invalid State

OK

EVAP Vent Sol.

EVAP

Open/Closed

Varies

EVAP Vent Sol.

ODD

OK/Fault/Invalid State

OK

Fans High Speed

Eng 2, Cat

On/Off

Off

Fans Low Speed

Eng 2, Cat

On/Off

Off

FC Relay 1

ODD

OK/Fault/Invalid State

OK

FC Relay 2 and 3

ODD

OK/Fault/Invalid State

OK

Fuel Level

EVAP

Percent

0-100

Fuel Pump

Eng 2

On/Off

On

Fuel Pump Ckt. History

ODD

OK/Stuck Low (open)/Stuck High/Fault

OK

Fuel Pump Ckt. Status

ODD

OK/Stuck Low (open)/Stuck High/Fault

OK

Fuel Tank Pressure

EVAP

in H2O/Volts

Varies

Fuel Trim Cell

Eng 1, Misfire

0-4

0

Fuel Trim Learn

Eng 1, Cat

Enabled/Disabled

Varies

HO2S Bank 1 Sensor 1

Eng 1, HO2S

Ready/Not Ready

Ready

HO2S Bank 2 Sensor 1

Eng 1, HO2S

Ready/Not Ready

Ready

HO2S Bank 1 Sensor 1

Eng 1, Cat, HO2S

millivolts

0-1000 and Varying

HO2S Bank 2 Sensor 1

Eng 1, Cat, HO2S

millivolts

0-1000 and Varying

HO2S Bank 1 Sensor 2

Eng 1, Cat, HO2S

millivolts

0-1000 and Varying

HO2S Warm-Up Bn1 Sen 1

HO2S

Min: Sec

Varies (under 2 minutes)

HO2S Warm-Up Bn2 Sen 1

HO2S

Min: Sec

Varies (under 2 minutes)

HO2S Warm-Up Bn1 Sen 2

HO2S

Min: Sec

Varies (under 2 minutes)

HO2S XCounts Bank 1

HO2S

Counts

Varies

HO2S XCounts Bank 2

HO2S

Counts

Varies

IAT

Eng 1, 2, EVAP, Cat, HO2S

°C/°F

Varies

Ignition 1

Eng 1, 2, EGR, HO2S, Cruise, TAC

Volts

Varies

Ignition Mode

Eng 2

IC/Bypass

IC

Injector Pulse Width

Eng 1, Cat

milliseconds

Varies (1.5-3.5)

Knock Retard

Eng 2

Degrees

0

Long Term FT Bank 1

Eng 1, Misfire

Percent

-10-10

Long Term FT Bank 2

Eng 1, Misfire

Percent

-10-10

Loop Status

Eng 1, Cat, HO2S, Misfire

Open/Closed

Closed

MAF

Eng 1, 2, Cat, HO2S, TAC

Grams per Second

3-6 (depends on altitude)

MAF Frequency

Eng 1

Hz

1200-3000 (depends on altitude)

MAP

Eng 1, 2, EGR, EVAP, TAC

kPa/Volts

20-48 kPa/0.75-2 Volts (depends on altitude)

MIL

Eng 2

On/Off

Off

MIL

ODD

OK/Fault/Invalid State

OK

Misfire Current Cyl. 1-6

Misfire

Counts

0

Misfire History Cyl. 1-6

Misfire

Counts

0

Misfiring Cylinder Prim.

Misfire

0-6

0

Misfiring Cylinder Sec.

Misfire

0-6

0

Power Enrichment

Eng 1, 2, Cat, HO2S, Misfire, Cruise, TAC

Active/Inactive

Inactive

Reduced Engine Power

Eng 1, 2, EGR, Cat, HO2S, Misfire, Cruise, TAC

Active/Inactive

Inactive

Rich/Lean Bank 1

Eng 1

Rich/Lean

Constantly Varying

Rich/Lean Bank 2

Eng 1

Rich/Lean

Constantly Varying

Short Term FT Bank 1

Eng 1, Cat, Misfire

Percent

-10-10

Short Term FT Bank 2

Eng 1, Cat, Misfire

Percent

-10-10

Spark

Eng 2

Degrees

20 (varies)

Starter Enable Relay

ODD

OK/Fault/Invalid State

OK

Starter Inhibit

Eng 2

Active/Inactive

Inactive

Start Up ECT

EVAP, HO2S

°C/°F

Varies

Start Up IAT

EVAP, HO2S

°C/°F

Varies

TAC Brake Switch

Cruise, TAC

Applied/Released

Released

TAC/PCM Communication

Eng 1, 2, EGR, Cat, HO2S, Cruise, TAC

OK/Fault

OK

TCC Enable Sol.

ODD

OK/Fault/Invalid State

OK

TCC Sol.

ODD

OK/Fault/Invalid State

OK

Total Misfire Current Count

Misfire

Counts

0

Total Misfire Failures Since First Fail

Misfire

Counts

0

Total Misfire Passes Since First Fail

Misfire

Counts

0

TP Desired Angle

Eng 1, 2, EGR, Cat, HO2S, Cruise, TAC

Percent

1-4

TP Indicated Angle

Eng 1, 2, EGR, Cat, HO2S, Misfire, Cruise, TAC

Percent

1-4

TP Sensor 1

TAC

Volts

0.5-1.2

TP Sensor 2

TAC

Volts

0.5-1.2

TP Sensor 1 Angle

TAC

Percent

2-4

TP Sensor 2 Angle

TAC

Percent

2-4

TP Sensors Disagree

TAC

Yes/No

No

TP Sensor 1 Out of Range

TAC

Yes/No

No

TP Sensor 2 Out of Range

TAC

Yes/No

No

Traction Control

Eng 2, Cruise

Active/Inactive

Inactive

Traction Control Desired Toque

Eng 2, Cruise

Percent

100%

Traction Control Torque

Eng 2, Cruise

Percent

65-80%

Transmission Range

Eng 2, Cruise (w/ automatic transmission)

Transmission Gear Position

Park

TR Switch A

Eng 2, Cruise (w/ automatic transmission)

Low/High

High

TR Switch B

Eng 2, Cruise (w/ automatic transmission)

Low/High

Low

TR Switch C

Eng 2, Cruise (w/ automatic transmission)

Low/High

High

TWC Protection

Eng 1, 2, Cat, HO2S, Misfire, Cruise, TAC

Active/Inactive

Inactive

Vehicle Speed

Eng 1, 2, EGR, Cat, Misfire, Cruise, TAC

MPH/Km/h

0

VTD Fuel Disable

Eng 2

Active/Inactive

Inactive