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 is completed
    • No 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:

Eng: Engine Data

CMP Actuator: Camshaft Position (CMP) Actuator Data

EVAP: Evaporative Emission (EVAP) Data

FUEL TRIM: Fuel Trim Data

HO2S: Heated Oxygen Sensor (HO2S) Data

Ignition: Ignition System Data

Induction: Induction Data

Misfire: Misfire Data

TAC: Throttle Actuator Control Data

Scan Tool Parameter

Data List

Units Displayed

Typical Data Value

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

5-Volt Reference 1 Circuit Status

EVAP, Ignition, Induction, TAC

OK/Fault

OK

5-Volt Reference 2 Circuit Status

EVAP, Ignition, Induction, TAC

OK/Fault

OK

A/C Relay Command

Eng, Indiction, Misfire, TAC

On/Off

Off

Air Flow Calculated

Eng, EVAP, Fuel Trim, HO2S, Induction, Misfire, TAC

g/s

3-6 g/s

Air Fuel Ratio

Eng, Fuel Trim, HO2S, Induction

Ratio

1.0

Ambient Air Temperature

Engine, EVAP

Degrees

Varies

APP Indicated Angle

CMP Actuator, Eng, EVAP, HO2S, Ignition, Induction, Misfire, TAC, Fuel Trim

Percent

0

APP Sensors

TAC

Percent

0

APP Sensor 1

TAC

Volts

Varies

APP Sensor 1 Indicated Position

TAC

Percent

0

APP Sensor 2

TAC

Volts

Varies

APP Sensor 2 Indicated Angle

TAC

Percent

0

APP Sensor 1 and 2

TAC

Agree/Disagree

Agree

BARO

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

kPa

65-110 kPa

BPP Signal

Engine, TAC

Applied/Released/Invalid

Released

BPP Signal Circuit

TAC

Applied/Released/Invalid

Released

Calc. TWC Temp.

Fuel Tim, Misfire

°C/°F

Varies

Catalytic Converter Protection Active

Fuel Trim, HO2S

Yes/No

No

CKP Active Counter

Ignition

Counts

Varies

CKP sensor

Ignition

RPM

650-950

CKP Resync Counter

Ignition

Counts

Varies

CMMD A/F Equivalence Ratio

Eng, Fuel Trim, HO2S, Induction

ratio

1:1

CMP Active Counter

CMP Actuator, Ignition

Counts

0-250

CMP Angle

CMP Actuator

Degrees of camshaft actuation

CMP Command

CMP Actuator

Percent

0%

CMP Sensor

CMP Actuator, Ignition, Misfire

RPM

Varies

CMP Solenoid Circuit Status

CMP Actuator

OK, Short to Gnd, Open, Short to B+, Incomplete

OK

CMP Variance

CMP Actuator

Degrees of camshaft actuation

CPP Switch (if equipped)

Engine, TAC

Applied/Released/Invalid

Released

Cruise Control Active

Engine, TAC

Active/Inactive/Invalid

Inactive

Cycles of Misfire Data

Misfire

Counts

0-99

Cylinder 1-6 Injector Circuit Status

Misfire

OK, Incomplete, Short B+, Short Gnd / Open

OK

Cylinder 1 and 4 IC Circuit Status

Misfire

OK, Incomplete, Short B+, Short Gnd / Open

OK

Cylinder 2 and 5 IC Circuit Status

Misfire

OK, Incomplete, Short B+, Short Gnd / Open

OK

Cylinder 3 and 6 IC Circuit Status

Misfire

OK, Incomplete, Short B+, Short Gnd / Open

OK

Cold Start Up

Eng, EVAP

Yes/No

Varies on startup

Decel Fuel Cut-off

Eng, Fuel Trim, HO2S

Active/Inactive

Inactive

Desired CMP

CMP Actuator

Degrees

Varies

Desired Idle Speed

CMP Actuator, Engine, EVAP, Induction, TAC

RPM

Varies

Distance Since DTC Cleared

Engine

Km/Miles

Varies

EC Ignition Relay Circuit Status

TAC

OK, Short to Gnd, Open, Short to B+, Incomplete

OK

EC Ignition Relay Feed Back Signal

Engine, TAC

Volts

13.0-14.2

EC Ignition Relay Command

Engine, TAC

ON/OFF

ON

ECT Sensor

CMP Actuator, Eng, EVAP, HO2S, Fuel Trim, Ignition, Induction, Misfire, TAC

°C/°F

Varies

Engine Load

CMP Actuator, Eng, Misfire, Fuel Trim, EVAP, HO2S, Ignition, Induction, TAC

Percent

0

Engine Oil Pressure Sensor

CMP Actuator, Engine, Misfire

kPa/PSI

15-25 PSI

Engine Oil Level Switch

CMP Actuator, Engine

Low/OK

OK

Engine Oil Life Remaining

CMP Actuator

Percent

Varies

Engine Oil Temperature

CMP Actuator

Degrees

Varies

Engine Off Time

EVAP

Hr: Min: Sec

Varies

Engine Run Time

CMP Actuator, Engine, EVAP, HO2S, Ignition, Induction, Misfire, TAC

Hr: Min: Sec

Varies

Engine Speed

CMP Actuator, Engine, EVAP, HO2S, Ignition, Induction, Misfire, Fuel Trim, TAC

RPM

Varies

EVAP Fault History

EVAP

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

No Fault

EVAP Purge Solenoid Circuit Status

EVAP

OK/Open/Short

OK

EVAP Purge Solenoid Command

Eng, EVAP, Fuel Trim, HO2S

Percent

0-2%

EVAP Vent Solenoid Circuit Status

EVAP

OK, Short to Gnd, Open, Short to B+, Incomplete

OK

EVAP Vent Solenoid Command

Eng, EVAP

Venting/Not Venting

Venting

Ext. Travel BPP Signal

TAC

Applied/Released/Invalid

Released

Fuel Alcohol Content

Fuel Trim

Percent

0-85%

Fuel Composition Learn

Fuel Trim

Active/Inactive

Active

Fuel Level Sensor

EVAP

Volts

Varies

Fuel Level Sensor

EVAP

percent

Varies

Fuel Pump Relay Circuit Status

Engine

OK, Short to Gnd, Open, Short to B+, Incomplete

OK

Fuel Pump Relay Command

Engine

On/Off

On

Fuel Tank Level Remaining

Engine, EVAP, Fuel Trim, Misfire

Percent

0-104

Fuel Tank Pressure Sensor

Engine, EVAP

mm Hg/in H2O

Varies

Fuel Tank Pressure Sensor

EVAP

Volts

Varies

Fuel Trim Cell

Engine, Fuel Trim

0-20

17

Fuel Trim Learn

Engine, Fuel Trim

Enabled/Disabled

Varies

Fuel Trim System Test State

Fuel Trim

Disabled/Enabled/Run Purge Test

Varies

Fuel Volatility

EVAP, Fuel Trim

Low/Moderate/High

Varies

HO2S  1

Engine, EVAP, Fuel Trim, Induction, HO2S

Millivolts

300-900 and Varying

HO2S 1 Heater Command

HO2S

Percent

Varies

HO2S 1 Heater Command

HO2S

Amps

Varies

HO2S 2

Eng, Fuel Trim, HO2S

Millivolts

400-600 and Varying

HO2S 2 Heater Command

HO2S

Percent

Varies

HO2S 2 Heater Command

HO2S

Amps

Varies

Fuel Tank Rated Capacity

EVAP

Gallons/Liters

Varies with vehicle option

Hot Open Loop

Fuel Trim, HO2S

Active/Inactive

Inactive

IAT Sensor

CMP Actuator, Engine, EVAP, Fuel Trim, HO2S, Ignition, Induction, Misfire, TAC

°C/°F

Varies

Ignition Accessory Signal

Engine, TAC

ON/OFF

OFF

Ignition 1 Signal

CMP Actuator, Engine, EVAP, Fuel Trim, HO2S, Ignition, Induction, Misfire, TAC

Volts

13.0-14.2

Injector PWM

Engine, Fuel Trim, HO2S, Misfire

Milliseconds

Varies

IMT Valve Command

Induction

ON/OFF

ON

IMT Valve Command

Induction

Open/Closed

Open

IMT Valve Feedback Signal

Induction

Percent

20-22%

IMT Valve Learn Enabled

Induction

YES/NO

YES

IMT Valve Position

Induction

Open, Intermediate, Closed

Open

IMT Valve Solenoid Circuit Status

Induction

OK, Short to Gnd, Open, Short to B+, Incomplete

OK

Knock Bank 1 Circuit Status

Ignition

Pass/Fail

Pass

KS Bank 2 Circuit Status

Ignition

Pass/Fail

Pass

Knock Detected Cylinder 1-6

Ignition

YES/NO

NO

LT FT Test Avg.

Fuel Trim

Percent

Varies

LT FT Test Avg. w/o Purge

Fuel Trim

Percent

Varies

Injector 1-6 Disabled Due to Misfire

Misfire

Yes/No

No

Intake Manifold Pressure

Fuel Trim, Induction

kPa

Varies

Knock Retard

Ignition

Degrees

0

Knock Sensor Bank 1 Circuit Status

Ignition

OK/Fault/Incomplete

OK

Knock Sensor Bank 2 Circuit Status

Ignition

OK/Fault/Incomplete

OK

KS Module Status

Ignition

Pass/Fail

Pass

Long Term FT

Eng, EVAP, Fuel Trim, HO2S

Percent

-10% to +10%

Loop Status

Eng, Fuel Trim, EVAP, HO2S

Open/Closed

Closed

MAF Sensor

CMP Actuator, Eng, EVAP, Fuel Trim, HO2S, Ignition, Induction, Misfire, TAC

g/s

3-6 (Varies with altitude)

MAF Sensor

EVAP, Fuel Trim, Induction,

Hz

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

MAF Performance Test

Fuel Trim, Induction, TAC

OK/Fault

OK

MAP Sensor

Induction

Volts

0.4-2.0 Volts

MAP Sensor

CMP Actuator, Eng, EVAP, Fuel Trim, HO2S, Ignition, Induction, Misfire, EGR, TAC

kPa

20-48 kPa (Varies with altitude)

MAP Performance Test 1

Fuel Trim, Induction, TAC

OK/Fault

OK

MAP Performance Test 2

Fuel Trim, Induction, TAC

OK/Fault

OK

MIL Command

Engine

On/Off

Off

MIL Circuit Status

Engine

OK, Short to Gnd, Open, Short to B+, Incomplete

OK

MIL Requested by DTC

CMP Actuator, Engine, EVAP, HO2S, Ignition, Induction, Misfire, TAC

YES/NO

NO

Misfire Current Cyl. 1-6

Misfire

Counts

0

Misfire History Cyl. 1-6

Misfire

Counts

0

PNP Switch (if equipped)

Engine

Park/Neutral

Park

Power Enrichment

Engine, Fuel Trim, HO2S, Misfire

Active/Inactive

Inactive

Reduced Engine Power

TAC

Active/Inactive

Inactive

ST FT Test Avg.

Fuel Trim

Percent

Varies

Short Term FT

Eng, EVAP, Fuel Trim, HO2S,

Percent

-10 to +10

Spark

Engine, Fuel Trim, HO2S, Ignition, Induction, Misfire

Degrees

22 (Varies)

Start Up ECT

EVAP, Fuel Trim, HO2S

°C/°F

Varies

Start Up IAT

EVAP, Fuel Trim, HO2S

°C/°F

Varies

TAC Forced Engine Shutdown

TAC

YES/NO

NO

TAC Motor

TAC

Enabled/Disabled

Enabled

TAC Motor Command

TAC

Percent

Varies

Torque Management Spark Retard

Ignition

Degrees

0

TCS Torque Request Signal

TAC

Percent

100%

TCS Torque Delivered Signal

TAC

Percent

75%

Total Knock Retard

Ignition

Degrees

0

Total Misfire

Misfire

Counts

0

TP Desired Angle

TAC

Percent

Varies

TP Indicated Angle

CMP Actuator, Engine, EVAP, Fuel Trim, HO2S, Ignition, Induction, Misfire, TAC

Percent

%

TP Performance Test

Fuel Trim, Induction, TAC

OK/Fault

OK

TP Sensor 1

TAC

Volts

Varies

TP Sensor 1 Indicated Position

TAC

Percent

0

TP Sensors 1 and 2

TAC

Agree/Disagree

Agree

TP Sensor 1 Learned Minimum

TAC

Volts

Varies

TP Sensor 2

TAC

Volts

Varies

TP Sensor 2 Indicated Position

TAC

Percent

0

TP Sensor 2 Learned Minimum

TAC

Volts

Varies

Vehicle Speed Sensor

CMP Actuator, Engine, EVAP, Fuel Trim, HO2S, Ignition, Induction, Misfire, TAC

mph/km/h

0

Warm-ups w/o Emission Faults

Engine

1-10

0

Warm-ups w/o Non-Emission Faults

Engine

1-10

0

Wide Open Throttle

TAC

YES/NO

NO