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 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:

CC: Cruise Data

Eng 1: Engine data 1

Eng 2: Engine data 2

EGR: Exhaust gas recirculation (EGR) data

EVAP: Evaporative emission (EVAP) data

FUEL TRIM: Fuel trim 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

3X Crank Sensor

Eng 2

RPM

Varies

18X Crank Sensor

Eng 2

RPM

Varies

A/C High Side Pressure Sensor

Eng 2

kPa/PSI/Volts

Varies

A/C Off For WOT

Eng 2

Yes/No

No

A/C Pressure Disable

Eng 2

Yes/No

No

A/C Relay Command

Eng 1, 2, Misfire, EGR

On/Off

Off

A/C Relay Circuit Status

ODD

OK/Fault/Invalid State

OK

A/C Request Signal

Eng 2

Yes/No

No

Air Fuel Ratio

Eng 2, Fuel Trim

Ratio

14.2:1-14.7:1

APP Average

TAC

Number

0

APP Indicated Angle

Eng 1, 2, EGR, EVAP, TAC, Fuel Trim, CC

Percent

0

APP Sensor 1

TAC

Volts

Varies

APP Sensor 2

TAC

Volts

Varies

APP Sensor 1

TAC

Percent

Varies

APP Sensor 2

TAC

Percent

Varies

APP Sensor 1 and 2

TAC

Agree/Disagree

Agree

BARO

Eng 1, EGR, EVAP, Fuel Trim

kPa

65-110 kPa

Boost Solenoid Circuit Status

ODD

OK/Fault/Invalid State

OK

Boost Solenoid Command

Engine 2

Percent

100%

CMP Sensor Signal Present

Eng 2

Yes/No

Yes

Cruise Control Active

Eng 1, CC, TAC

Yes/No

No

Cruise Disengage History 1-6

CC

None

None

Cruise Mode Signal

CC

Volts

0.0

Cruise ON/OFF Switch

CC, TAC

On/Off

Off

Cruise Resume/Accel Switch

CC, TAC

On/Off

Off

Cruise Set/Coast Switch

CC, TAC

On/Off

Off

Current Gear

Eng 1, Eng 2, EGR, Fuel Trim

1, 2, 3, 4

1

Cycles of Misfire Data

Misfire

Counts

0-99

Cyl. 1-6 Injector Circuit Status

ODD

OK/Stuck Low (open)/Stuck High

OK

Decel Fuel Cut-off

EGR, Fuel Trim

Active/Inactive

Inactive

Desired EGR Position

Eng 1, EGR, Misfire

Percent

0

Desired EGR Position

EGR

Volts

0

Desired Idle Speed

Eng 1, 2, 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

ODD

OK/ Fault/ Invalid State

OK

ECT Sensor

Eng 1, 2, EGR, EVAP, Misfire, Fuel Trim

°C/°F

Varies

EGR Flow Test Count

EGR

Counts

0-12

EGR Learned Minimum Position

EGR

Volts

0.14-1.0

EGR Position Sensor

Eng 1, EGR, Misfire

Percent

Varies

EGR Position Sensor

EGR

Volts

0

EGR Position Variance

EGR

Percent

0

EGR Solenoid Circuit Status

ODD

OK/Fault/ Invalid State

OK

EGR Solenoid Command

EGR

Percent

0

Engine Load

Eng 1, 2, Misfire, Fuel Trim, EVAP, EGR, CC, TAC

Percent

0

Engine Oil Level Switch

Eng 2

OK/Low

OK

Engine Oil Life Remaining

Eng 2

Percent

0-100% (Varies)

Engine Oil Pressure Switch

Eng 2

Low/OK

OK

Engine Run Time

Eng 1, 2, EVAP, Misfire, Fuel Trim, EGR, CC, TAC

Hr: Min: Sec

Varies

Engine Speed

Eng 1, 2, EGR, EVAP, Misfire, Fuel Trim, CC, TAC

RPM

Varies

EVAP Fault History

EVAP

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

No Fault

EVAP Purge Solenoid Circuit Status

ODD

OK/Fault/Invalid State

OK

EVAP Purge Solenoid Command

Eng 1, EVAP, Fuel Trim

Percent

Varies

EVAP Vent Solenoid Command

Eng 1, EVAP, Fuel Trim

Venting/Not Venting

Varies

EVAP Vent Solenoid Circuit Status

ODD

OK/Fault/Invalid State

OK

FC Relay 1 Circuit Status

ODD

OK/Fault/Invalid State

OK

FC Relay 1 Command

Eng 2

On/Off

Off

FC Relay 2 and 3 Circuit Status

ODD

OK/Fault/Invalid State

OK

FC Relay 2 and 3 Command

Eng 2

On/Off

Off

Fuel Pump Relay Circuit Status

ODD

OK/Fault/Invalid State

OK

Fuel Pump Relay Command

Eng 1

On/Off

On

Fuel Tank Level Remaining

EVAP

Percent

0-104

Fuel Tank Pressure Sensor

Eng 1, EVAP

mm Hg/in H2O

Varies

Fuel Tank Pressure Sensor

EVAP

Volts

Varies

Fuel Trim Cell

EVAP, Eng 1, Fuel Trim

0-4

0

Fuel Trim Learn

Eng 1, EVAP, Fuel Trim

Enabled/Disabled

Varies

GEN L-Terminal Signal Command

Eng 2

On/Off

Off

HO2S 1

EVAP, Eng 1, Fuel Trim

millivolts

0-1000 and Varying

HO2S 2

Eng 1, Fuel Trim

millivolts

0-1000 and Varying

HO2S 1 Heater Circuit Status

ODD

OK/ Fault

OK

HO2S 2 Heater Circuit Status

ODD

OK/ Fault

OK

HO2S 1 Heater Command

Eng 2

On/Off

On

HO2S 2 Heater Command

Eng 2

On/Off

On

HO2S 1 Heater Current

Eng 2

Amps

Varies

HO2S 2 Heater Current

Eng 2

Amps

Varies

IAT Sensor

Eng 1, 2, EVAP, EGR, Fuel Trim

°C/°F

Varies

Ignition 1 Signal

EVAP, Eng 1, 2, EGR, Fuel Trim, CC, TAC

Volts

Varies

Ignition Mode

Eng 2

IC/Bypass

IC

IMS

Eng 1, 2, EGR, Fuel Trim, CC

P, R, N, D4, D, 3, D2, D1

P

Initial Brake Apply Signal

CC, TAC

Released/ Applied

Released

Injector PWM

Eng 2, Fuel Trim, Misfire

milliseconds

Varies

Knock Retard

Eng 1, EGR

Degrees

0

Long Term FT

Eng 1, 2, EVAP, Fuel Trim

Percent

-10% to +10%

Loop Status

Eng 1, 2, Fuel Trim, EVAP, EGR

Open/Closed

Closed

MAF Sensor

Eng 1, 2, EGR, Misfire, EVAP, Fuel Trim, TAC

g/s

3-6 (Varies with altitude)

MAF Sensor

Eng 2

Hz

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

MAP Sensor

Eng 1, 2

Volts

0.4-2.0 Volts

MAP Sensor

Eng 1, 2, EVAP, Fuel Trim, Misfire, EGR, TAC

kPa

20-48 kPa (Varies with altitude)

MIL Command

Eng 2

On/Off

Off

MIL Circuit Status

ODD

OK/Fault/Invalid State

OK

Misfire Current Cyl. 1-6

Misfire

Counts

0-4

Misfire History Cyl. 1-6

Misfire

Counts

0

Number of DTCs

Eng 1, EVAP, Fuel Trim, TAC

Number

0

PCM/VCM in VTD Fail/Enable

Eng 1

Yes/No

No

Power Enrichment

Eng 2, Misfire

Active/Inactive

Inactive

Reduced Engine Power

Eng 1, TAC, Misfire, CC

Active/Inactive

Inactive

Short Term FT

Eng 1, 2, EVAP, Fuel Trim

Percent

-10 to +10

Spark

Eng 1, 2, Misfire, Fuel Trim

Degrees

22 (varies)

Starter Enable Relay Circuit Status

ODD

OK/ Fault

OK

Starter Relay Command

Eng 2

On/Off

Off

Start Up ECT

EVAP, Fuel Trim

°C/°F

Varies

Start Up IAT

EVAP, Fuel Trim

°C/°F

Varies

Stop Lamp Signal

CC, TAC

On/Off

Off

TAC/PCM Communications Signal

Eng 1, CC, TAC

OK/ Fault

OK

TCC Brake Pedal Switch

Eng 2

Applied/Released

Released

TCC PWM Solenoid Circuit Status

ODD

OK/ Fault/ Invalid State

OK

TCC PWM Solenoid Command

Eng 2, Misfire, CC

On/Off

Off

TCS Delivered Torque Circuit Status

ODD

OK/ Fault

OK

Torque Request Signal (If Equipped)

Eng 2, TAC

Percent

100%

Torque Delivered Signal (If Equipped)

Eng 2, TAC

Percent

75%

TP Desired Angle

Eng 1, 2, EGR, TAC, Fuel Trim, EVAP, CC

Percent

Varies

TP Indicated Angle

Eng 1, 2, EGR, Fuel Trim, EVAP, Misfire, CC, TAC

Percent

%

TP Sensor 1

TAC

Volts

Varies

TP Sensor 2

TAC

Volts

Varies

TP Sensor 1

TAC

Percent

Varies

TP Sensor 2

TAC

Percent

Varies

TP Sensor 1 and 2

TAC

Agree/ Disagree

Agree

Traction Control Status (If Equipped)

Eng 2, CC, TAC

Active/Inactive

Inactive

Vehicle Speed Sensor

Eng 1, 2, EGR, EVAP, Fuel Trim, Misfire, CC, TAC

mph/ km/h

0

VTD Auto Learn Timer

Eng 1

Active/ Inactive

Inactive

VTD Fuel Disable

Eng 1

Active/ Inactive

Inactive

VTD Fuel Disable until Ignition Off

Eng 1

Yes/No

No