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
    • 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

AC Relay CKT Short to Ground

General Info-Outputs

Yes/No

Yes

AC Relay CKT Short to Voltage

General Info-Outputs

Yes/No

No

A/C High Side Pressure

General Info-Outputs, 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 Request

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

Yes/No

No

Air Flow

Engineering

Grams/Sec

--

Air Fuel Ratio

Fuel and Emissions

Ratio

--

Air Pump Rel. CKT Open or Short to Ground

General Info-Outputs

Yes/No

No

Air Pump Rel. CKT Short to Voltage

General Info-Outputs

Yes/No

No

Air Pump Relay Commanded

General Info-Outputs

On/Off

Off

AIR Pump Relay Command

Auxiliary Emissions

On/Off

--

BARO

Fuel and Emissions

kPa

--

CAL. Compression Output

Misfire

Counts

--

Calc Converter Temp

Engineering

°C/°F

--

CKP Active Counter

General Info-Inputs, Ignition

Counts

--

CMP Active Counter

General Info-Inputs, Ignition

Counts

--

CMP Resync Counter

General Info-Inputs, Ignition

Counts

--

Cooling Fan Relay CMD

General Info-Outputs, Output Driver Status

On/Off

0=Off

1=ON

Cruise Brake Switch/ Clutch Switch

General Info, Inputs, Idle/Speed Control

Released/Applied

--

Cruise Engaged

General Info-Inputs,

Yes/No

No

Cruise Engaged

Idle/Speed Control

On/Off

--

Current IAC Memory

Engineering

Counts

--

Decel Fuel Cut-Off

Fuel and Emissions

Yes/No

--

Desired Idle Speed

Idle/Speed Control

RPM

--

ECT

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

°C/°F

--

Engine LOAD

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

%

--

Engine Oil Life Remaining

General Info-Inputs

%

--

Engine Run Time

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

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 Purge CKT Open or Short to Ground

General Info-Outputs

Yes/No

No

EVAP Purge CKT Short to Voltage

General Info-Outputs

Yes/No

No

EVAP Purge Solenoid DC

General Info-Outputs, Fuel and Emissions, Auxiliary Emissions

%

--

EVAP Tank Vac. Slope

Engineering

mm Hg/in H2O

--

EVAP Vent CKT Open or Short to Ground

General Info-Outputs

Yes/No

No

EVAP Vent CKT Short to Voltage

General Info-Outputs

Yes/No

No

EVAP Vent Solenoid

General Info-Outputs, Auxiliary Emissions

On/Off

--

FC 1 Relay CKT Open or Short to Ground

General Info-Outputs

Yes/No

No

FC 1 Relay CKT Short to Voltage

General Info-Outputs

Yes/No

No

FC 2 Relay CKT Open or Short to Ground

General Info-Outputs

Yes/No

No

FC 2 Relay CKT Short to Voltage

General Info-Outputs

Yes/No

No

Fan Control 1 Command

General Info-Outputs

On/Off

Off

Fan Control 2 Command

General Info-Outputs

On/Off

Off

Fuel Level

General Info-Inputs/Ignition/Fuel and Emissions

%

--

Fuel Tank Pressure

General Info-Inputs

mm Hg/in H2O

--

Fuel Tank Pressure Sensor

General Info-Inputs, Auxiliary Emissions

Volts

--

Fuel Trim Cell

Fuel and Emissions

Cell #

--

Fuel Trim Index

Fuel and Emissions

%

--

Generator F Terminal DC

General Info Outputs

%

--

Generator L Terminal

General Info Outputs

Disabled/Enabled

0=Disabled

1=Enabled

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

IAT

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

°C/°F

--

Ignition 1

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

Volts

--

Injector PWM

Fuel and Emissions

Milliseconds (ms)

--

KS Active Counter

Ignition

Counts

--

Knock Retard

Ignition

Degree

--

Knock Sensor 1

General Info-Inputs, Ignition

Volts

--

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 Oil Pressure

General Info Inputs

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

--

Misfire Current #1-4

Misfire

Counts

--

Misfire History #1-4

Misfire

Counts

--

Module Driver Overtemp

General Info-Outputs

Yes/No

No

Module Driver Overvoltage

General Info-Outputs

Yes/No

No

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, General Info-Inputs

%

--

Spark

Ignition

Degree (BTDC)

--

Start Up ECT

Fuel and Emissions

°C/°F

--

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

%

--

Total Misfire Count

Misfire

Counts

--

Vehicle Speed

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

km/h / mph

Varies