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. The parameters in the Typical Scan Data values column represent values that would be seen on a normally running engine.

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

Only the parameters listed below are referred to in this service manual for use in diagnosis. For further information on using the scan tool to diagnose the ECM and related sensors, refer to the applicable reference section listed below. If all values are within the typical range described below, refer to Symptoms - Engine Controls . The Typical Scan Data Values table contains all the parameters included in the following data lists arranged in alphabetical order:

    • General Info--Inputs
    • General Info--Outputs
    • Fuel and Emissions
    • Ignition
    • Misfire
    • Auxiliary Emissions
    • Idle/Speed Control
    • Output Driver Status
    • Engineering

For scan tool parameter definitions, refer to Scan Tool Data Definitions .

Important: Use the Typical Scan Data Values only after the following conditions are met:

    • The Diagnostic System Check - Engine Controls has been completed.
    • The engine is idling unless checking a value at a specified RPM.
    • The throttle is closed unless checking a value at a specified RPM.
    • The vehicle is in PARK or NEUTRAL.
    • The vehicle is operating in Closed Loop.
    • The vehicle accessories are turned OFF.

Scan Tool Parameter

Data List

Units Displayed

Typical Data Value

A/C High Side Pressure

General Info-Inputs

Volts

--

A/C Relay Command

General Info-Inputs, General Info-Outputs, Idle/Speed Control, Output Driver Status

On/Off

Off unless commanded On

A/C Relay - High Volts

Output Driver Status

Test Not Run/Test Pass

--

A/C Relay - Low Volts

Output Driver Status

Test Not Run/Test Pass

--

A/C Relay - Open

Output Driver Status

Test Not Run/Test Passed

--

A/C Request

General Info-Inputs, General Info-Outputs, Idle/Speed Control

Yes/No

No

Air Flow Calculated

Engineering/Fuel and Emissions

Grams/Sec

--

Air Fuel Ratio

Fuel and Emissions

Ratio

--

BARO

Fuel and Emissions

kPa

--

Brake Switch

General Info-Inputs, Idle/Speed Control

Applied/Released

--

Calc Converter Temp

Engineering

°C/°F

--

Clutch Pedal Switch

General Info Input

Released/Applied

--

CMP Resync Counter

General Info-Inputs, Ignition

Counts

--

Cooling Fan Relay CMD

General Info-Outputs, Output Driver Status

On/Off

0=Off

1=ON

Cooling Fan Relay - High

Output Driver Status

Test Not Run/Test Passed

--

Cooling Fan Relay - Low

Output Driver Status

Test Not Run/Test Passed

--

Cooling Fan Relay - Open

Output Driver Status

Test Not Run/Test Passed

--

Crank Learned

Misfire

Yes

No

Cruise Brake Switch

General Info, Inputs, Idle/Speed Control

Released/Applied

--

Cruise Control Clutch - High Volts

Output Driver Status

Test Not Run/Test Passed

--

Cruise Control Clutch - Low Volts

Output Driver Status

Test Not Run/Test Passed

--

Cruise Control Clutch - Open

Output Driver Status

Test Not Run/Test Passed

--

Cruise Control Dir. Ckt - High Volts

Output Driver Status

Test Not Run/Test Passed

--

Cruise Control Dir. Ckt - Low Volts

Output Driver Status

Test Not Run/Test Passed

--

Cruise Control Dir. Ckt - Open

Output Driver Status

Test Not Run/Test Passed

--

Cruise Clutch Command

Idle/Speed Control, Output Driver Status

On/Off

0=Off

1=ON

Cruise Delta

Idle/Speed Control

km/h/mph

--

Cruise Direction Command

Idle/Speed Control, Output Driver Status

No/Yes

--

Cruise Gear Out of Range

Idle/Speed Control

--

--

Cruise In Release State

Idle/Speed Control

Yes/No

0=No

1=Yes

Cruise Move Ckt - High Volts

Output Driver Status

Test Not Run/Test Passed

--

Cruise Move Ckt - Low Volts

Output Driver Status

Test Not Run/Test Passed

--

Cruise Move Ckt - Open

Output Driver Status

Test Not Run/Test Passed

--

Cruise Move Command

Output Driver Status

On/Off

--

Cruise Off Brake

Idle/Speed Control

Off/On

--

Cruise Resume/Accel

General Info-Inputs, Idle/Speed Control

On/Off

0=Off

1=ON

Cruise RPM Out of Range

Idle/Speed Control

Yes/No

--

Cruise Set/Coast

General Info-Inputs, Idle/Speed Control

On/Off

0=Off

1=ON

Cruise Set Speed

Idle/Speed Control

km/h /mph

--

Cruise Switch

General Info-Inputs, Idle/Speed Control

On/Off

0=Off

1=ON

Cruise Switch Voltage

Idle/Speed Control

Volts

--

Cruise Traction Active

Idle/Speed Control

Yes/No

--

Cruise Trans Range SW

Idle/Speed Control

Yes/No

--

Cruise Volt Out of Range

Idle/Speed Control

Yes/No

--

Cruise VSS Out of Range

Idle/Speed Control

--

--

Decel Fuel Off

Fuel and Emissions

Yes/No

--

Decel Rich Fault

Fuel and Emissions

Yes/No

--

Desired Idle Speed

Idle/Speed Control

RPM

--

Dist. Since Code Clear

Engineering

km/miles

--

ECT

General Info-Inputs, General Info-Outputs, Fuel and Emissions, Misfire, Auxiliary Emissions, Idle/Speed Control, Engineering

°C/°F

--

Engine LOAD

General Info-Inputs, General Info-Outputs, Fuel and Emissions, Misfire, Auxiliary Emissions, Idle/Speed Control, Engineering

%

--

Engine Oil Life Remaining

General Info-Inputs

%

--

Engine Oil Life Reset

General Info-Inputs

Yes/No

0=No

1=Yes

Engine Run Time

General Info-Inputs, General Info-Outputs, Fuel and Emissions, Misfire, Auxiliary Emissions, Idle/Speed Control, Engineering

H:MM:SS

--

Engine Speed

General Info-Inputs, General Info-Outputs, Fuel and Emissions, Misfire, Auxiliary Emissions, Idle/Speed Control, Engineering, Ignition

RPM

Varies

EVAP Large Leak

Auxiliary Emissions

Not Ran/Pass/Fail

0,0=Not Ran

1,0=Fail

0,1=Pass

EVAP Pressure Slope

Engineering

H2O/Sec

--

EVAP Purge - High Volts

Output Driver Status

Test Not Run/Test Passed

--

EVAP Purge - Low Volts

Output Driver Status

Test Not Run/Test Passed

--

EVAP Purge - Open

Output Driver Status

Test Not Run/Test Passed

--

EVAP Purge Solenoid

General Info-Outputs, Output Driver Status

On/Off

0=Off

1=ON

EVAP Purge Solenoid DC

General Info-Outputs, Fuel and Emissions, Auxiliary Emissions

%

--

EVAP Purge Valve Leak

Auxiliary Emissions

Not Ran/Pass/Fail

0,0=Not Ran

1,0=Fail

0,1=Pass

EVAP System Small Leak

Auxiliary Emissions

Not Ran/Pass/Fail

0,0=Not Ran

1,0=Fail

0,1=Pass

EVAP Tank Vac. Filtered

Engineering

H2O/Sec

--

EVAP Tank Vac. Slope

Engineering

mm Hg/s /in H2O/s

--

EVAP Vent Blockage

Auxiliary Emissions

Not Ran/Pass/Fail

0,0=Not Ran

1,0=Fail

0,1=Pass

EVAP Vent - High Volts

Output Driver Status

Test Not Run/Test Passed

--

EVAP Vent - Low Volts

Output Driver Status

Test Not Run/Test Passed

--

EVAP Vent - Open

Output Driver Status

Test Not Run/Test Passed

--

EVAP Vent Solenoid

General Info-Outputs, Output Driver Status

On/Off

--

Fuel Cutoff

Fuel and Emissions

On/Off

--

Fuel Level Sensor

Fuel and Emissions/Ignition

Volts

--

Fuel Level

General Info-Inputs/Ignition/Fuel and Emissions

%

--

Fuel Pump Relay - High Volts

Output Driver Status

Test Not Run/Test Passed

--

Fuel Pump Relay - Low Volts

Output Driver Status

Test Not Run/Test Passed

--

Fuel Pump Relay - Open

Output Driver Status

Test Not Run/Test Passed

--

Fuel Pump Relay Command

General Info-Outputs, Output Driver Status

On/Off

0=Off

1=ON

Fuel Tank Pressure

General Info-Inputs, Auxiliary Emissions

mm Hg/in H2O

--

Fuel Tank Pressure Sensor

General Info-Inputs, Auxiliary Emissions

Volts

--

Fuel Trim Cell

Fuel and Emissions

Cell #

--

Generator F Terminal DC

General Info Inputs

%

--

Generator L Terminal

General Info Inputs

Disabled/Enabled

0=Disabled

1=Enabled

High Spark Modifier

Ignition

Degree

--

HO2S 1, 2 Heater Command

Output Driver Status, General Info Inputs

On/Off

0=Off

1=ON

HO2S 1, 2

General Info-Inputs, Fuel and Emissions, Auxiliary Emissions

mV

0-1,000 mV and varying

HO2S 1, 2 Heater Current

Auxiliary Emissions, General Info, Fuel and Emissions

Amps

0.5-0.6 Amps

HO2S 1, 2 Heater - High Volts

Output Driver Status

Test Not Run/Test Passed

--

HO2S 1, 2 Heater - Low Volts

Output Driver Status

Test Not Run/Test Passed

--

HO2S 1, 2 Heater - Open

Output Driver Status

Test Not Run/Test Passed

--

IAC Motor Ckt - High Volts

Output Driver Status

Test Pass/Fail

--

IAC Motor Command

Output Driver Status

On/Off

--

IAC Position

Idle/Speed Control

Counts

--

IAC Position with A/C

Engineering, Idle/Speed Control

Counts

--

IAC Position without A/C

Engineering, Idle/Speed Control

Counts

--

IAT

General Info-Inputs, General Info-Outputs, Fuel and Emissions, Misfire, Auxiliary Emissions, Idle/Speed Control, Engineering, Ignition

°C/°F

--

Ign. Coil 1 and 4 - Command

Output Driver Status

On/Off

--

Ign. Coil 1 and 4 - High Volts

Output Driver Status

Test Not Run/Test Passed

--

Ign. Coil 1 and 4 - Low Volts

Output Driver Status

Test Not Run/Test Passed

--

Ign. Coil 1 and 4 - Open

Output Driver Status

Test Not Run/Test Passed

--

Ign. Coil 2 and 3 - Command

Output Driver Status

On/Off

--

Ign. Coil 2 and 3 - High Volts

Output Driver Status

Test Not Run/Test Passed

--

Ign. Coil 2 and 3 - Low Volts

Output Driver Status

Test Not Run/Test Passed

--

Ign. Coil 2 and 3- Open

Output Driver Status

Test Not Run/Test Passed

--

Ignition 1

General Info-Inputs, General Info-Outputs, Fuel and Emissions, Misfire, Auxiliary Emissions, Idle/Speed Control, Engineering

Volts

--

Injector PWM

Fuel and Emissions

Milliseconds (ms)

--

Injector 1-4 Command

Output Driver Status

On/Off

0=Off

1=ON

Injector 1-4 - High Volts

Output Driver Status

Test Not Run/Test Passed

--

Injector 1-4 - Low Volts

Output Driver Status

Test Not Run/Test Passed

--

Injector 1-4 - Open

Output Driver Status

Test Not Run/Test Passed

--

KS Noise

Ignition

Counts

--

Knock Retard

Ignition

Degree

--

Lean/Rich Avg. Time

Engineering

Milliseconds (ms)

--

Lean/Rich Transitions

Engineering

Counts

--

Long Term FT

Fuel and Emissions, Auxiliary Emissions, Ignition

%

--

Loop Status

Fuel and Emissions

Open/On

0=Open

1=ON

Low Coolant Level

General Info-Inputs, Idle/Speed Control

Yes/No

--

Low Oil Pressure

General Information

No/Yes

--

Low Spark Modifier

Ignition

Degree

--

MAP

General Info-Inputs, General Info-Outputs, Fuel and Emissions, Misfire, Auxiliary Emissions, Idle/Speed Control, Engineering, Ignition

kPa

--

MAP Sensor

General Info-Inputs

Volts

--

MIL Command

Output Driver Status

On/Off

0=Off

1=ON

M/T Clutch Disengaged

Idle/Speed Control

Yes/No

--

Mid Spark Modifier

Ignition

Degree

--

MIL High Volts

Output Driver Status

Test Not Run/Test Pass

--

MIL Low Volts

Output Driver Status

Test Not Run/Test Pass

--

MIL Open

Output Driver Status

Test Not Run/Test Status

--

Misfire Current #1-4

Misfire

Counts

--

Misfire Enabled

Misfire

Yes/No

0=No

1=Yes

Misfire History #1-4

Misfire

Counts

--

O2S 1

General Info-Inputs, Fuel and Emissions, Auxiliary Emissions

Millivolts

--

O2S Transition Time Ratio

Engineering

Ratio

--

Park Brake Switch

Idle/Speed Control

Off/On

--

Park/Neutral Switch

Idle/Speed Control

R, D, L, P, N

0=R, D, L

1=P, N

Power Enrichments

Fuel and Emissions

Inactive/Active

--

Rich/Lean Avg. Time

Engineering

Milliseconds (ms)

--

Rich/Lean Transitions

Engineering

Counts

--

Seed and Key Timer

Engineering

Seconds

--

Short Term FT

Fuel and Emissions, Auxiliary Emissions, Ignition

%

--

Spark

Ignition

Degree (BTDC)

--

Starter Relay Command

Output Driver Status

On/Off

--

Starter Relay-High Volts

Output Driver Status

Test Pass/Test Not Run

--

Starter Relay- Low Volts

Output Driver Status

Test Pass/Test Fail

 

Starter Relay-Open

Output Driver Status

Test Pass/Test Fail

--

Start Up ECT

Fuel and Emissions

°C/°F

--

Steering Assist Sol. DC

General Info-Inputs

%

--

Steering Sol. Command

Output Driver Status

--

--

Steering Solenoid - High Volts

Output Driver Status

--

--

Steering Solenoid - Low Volts

Output Driver Status

--

--

Steering Solenoid - Open

Output Driver Status

--

--

System Power Mode

General Info Inputs

Run/Off

--

TP Sensor

General Info-Inputs, Idle/Speed Control

Volts

--

TP Angle

General Info-Inputs, General Info-Outputs, Fuel and Emissions, Misfire, Auxiliary Emissions, Idle/Speed Control, Engineering, Ignition

%

--

Vehicle Speed

General Info-Inputs, General Info-Outputs, Fuel and Emissions, Misfire, Auxiliary Emissions, Idle/Speed Control, Engineering, Ignition

km/h / mph

Varies

VTD Fail Enable

Engineering

On/Off

--

VTD Fuel Cutoff

--

Yes/No

0=No

1=Yes

VTD Fuel Disable

Engineering

Active/Inactive

--