GM Service Manual Online
For 1990-2009 cars only

The Engine Scan Tool Data List contains all engine controls-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 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:

CMP: CMP actuator data

Eng: Engine data

EVAP: Evaporative emission (EVAP) data

FT: Fuel trim data

HO2S: Heated oxygen sensor (HO2S) data

Ind: Induction data

Ign: Ignition system data

I/M: I/M data

Misfire: Misfire data

TAC: Throttle actuator control Data

Scan Tool Parameter

Data List

Units Displayed

Typical Data Value

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

5-Volt Reference 1

EVAP, Ign, Ind, TAC

Volts

5.0

5-Volt Reference 1 Circuit Status

EVAP, Ign, Ind, TAC

OK/Fault

OK

5-Volt Reference 2

EVAP, Ign, Ind, TAC

Volts

5.0

5-Volt Reference 2 Circuit Status

EVAP, Ign, Ind, TAC

OK/Fault

OK

Air Flow Calculated

Eng, EVAP, FT, HO2S, Ind, Misfire, TAC

g/s

Varies

Ambient Air Temperature

Eng

°C/°F

Varies

APP Indicated Angle

Eng, CMP, EVAP, FT, HO2S, Ign, Ind, Misfire, TAC

%

0

APP Sensor 1

TAC

Volts

0.88

APP Sensor 1 and 2

TAC

Agree/Disagree

Agree

APP Sensor 1 Indicated Position

TAC

%

0

APP Sensor 2

TAC

Volts

0.88

APP Sensor 2 Indicated Position

TAC

%

0

APP Sensors

TAC

%

0

BARO

Eng, EVAP, FT, HO2S, Ign, Ind, I/M

kPa

60-104 (varies with altitude)

Calc. TWC Temp. Bank 1

FT, Misfire

°C/°F

Varies

Calc. TWC Temp. Bank 2

FT, Misfire

°C/°F

Varies

Catalyst Monitor Complete This Ignition

I/M

Yes/No

Varies

Catalyst Monitor Enabled This Ignition

I/M

Yes/No

Yes

Catalytic Converter Protection Active

FT, HO2S

Yes/No

No

CKP Active Counter

Ign

Counts

0-255 incrementing

CKP Resync Counter

Ign

Counts

0

CKP Sensor

Ign

RPM

700-750

Cmmd. A/F Equivalence Ratio

Eng, FT, HO2S, Ind

:1

1.0

CMP Active Counter

CMP, Ign

Counts

0-255 incrementing

CMP Angle

CMP

Degrees

0

CMP Command

CMP

%

0

CMP Sensor

CMP, Ign, Misfire

RPM

610-690

CMP Solenoid Circuit Status

CMP

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

OK

CMP Variance

CMP

Degrees

0

Cold Startup

EVAP, I/M

Yes/No

Varies

Cycles of Misfire Data

Misfire

Counts

0-100 incrementing

Cylinder 1 and 4 IC Circuit Status

Misfire

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

OK

Cylinder 1 Injector Circuit Status

Misfire

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

OK

Cylinder 2 and 5 IC Circuit Status

Misfire

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

OK

Cylinder 2 Injector Circuit Status

Misfire

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

OK

Cylinder 3 and 6 IC Circuit Status

Misfire

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

OK

Cylinder 3 Injector Circuit Status

Misfire

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

OK

Cylinder 4 Injector Circuit Status

Misfire

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

OK

Cylinder 5 Injector Circuit Status

Misfire

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

OK

Cylinder 6 Injector Circuit Status

Misfire

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

OK

Decel. Fuel Cutoff

Eng, FT, HO2S

Active/Inactive

Inactive

Desired CMP

CMP

Degrees

0

Desired Idle Speed

Eng, CMP, EVAP, Ind, TAC

RPM

648

Distance Since DTC Cleared

Eng

km/miles

Varies

EC Ignition Relay Circuit Status

TAC

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

OK

EC Ignition Relay Command

Eng, TAC

On/Off

On

EC Ignition Relay Feedback Signal

Eng, TAC

Volts

13.5

ECT Sensor

Eng, CMP, EVAP, FT, HO2S, Ign, Ind, Misfire, TAC, I/M

°C/°F

99/210

Engine Load

Eng, CMP, EVAP, FT, HO2S, Ign, Ind, Misfire, TAC

%

Varies

Engine Off Time

EVAP

Seconds

Varies

Engine Run Time

Eng, CMP, EVAP, FT, HO2S, Ign, Ind, I/M, Misfire, TAC

Hr:Min:Sec

Varies

Engine Speed

Eng, CMP, EVAP, FT, HO2S, Ign, Ind, Misfire, TAC

RPM

610-690

EVAP Fault History

EVAP

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

No Fault

EVAP Monitor Complete This Ignition

I/M

Yes/No

Varies

EVAP Monitor Enabled This Ignition

I/M

Yes/No

No

EVAP Purge Solenoid Circuit Status

EVAP

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

OK

EVAP Purge Solenoid Command

Eng, EVAP, FT, HO2S

%

20

EVAP Vent Solenoid Circuit Status

EVAP

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

OK

EVAP Vent Solenoid Command

Eng, EVAP

Venting/Not Venting

Venting

Fuel Level Sensor

EVAP

Volts

Varies

Fuel Pump Relay Command

Eng

On/Off

On

Fuel Tank Level Remaining

Eng, EVAP, FT, Misfire, I/M

%

Varies

Fuel Tank Pressure Sensor

Eng, EVAP

mm Hg/in H2O

-19.8 to +12.52/-10.5 to +6.17

Fuel Tank Pressure Sensor

EVAP

Volts

0.2-4.0

Fuel Tank Rated Capacity

EVAP

Liters/Gallons

Varies

Fuel Trim Cell

Eng, FT

Cell

17

Fuel Trim Learn

FT

Enabled/Disabled

Enabled

Fuel Trim System Test State

FT

Disabled/Monitoring/Run Purge Test/Report

Monitoring

Fuel Volatility

EVAP, FT

Low, Moderate, High

Varies

HO2S Bank 1 Sensor 1

Eng, EVAP, FT, HO2S, Ind

mV

0-1,000

HO2S Bank 1 Sensor 1 Heater

HO2S

Amps

0.50-1.00

HO2S Bank 1 Sensor 1 Heater Circuit Status

HO2S

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

OK

HO2S Bank 1 Sensor 1 Heater Command

HO2S

On/Off

On

HO2S Bank 1 Sensor 1 Heater Command

HO2S

%

7-60

HO2S Bank 1 Sensor 2

Eng, FT, HO2S

mV

0-1,000

HO2S Bank 1 Sensor 2 Heater

HO2S

Amps

0.50-1.00

HO2S Bank 1 Sensor 2 Heater Circuit Status

HO2S

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

OK

HO2S Bank 1 Sensor 2 Heater Command

HO2S

On/Off

On

HO2S Bank 1 Sensor 2 Heater Command

HO2S

%

7-90

HO2S Bank 2 Sensor 1

Eng, EVAP, FT, HO2S, Ind

mV

0-1,000

HO2S Bank 2 Sensor 1 Heater

HO2S

Amps

0.50-1.00

HO2S Bank 2 Sensor 1 Heater Circuit Status

HO2S

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

OK

HO2S Bank 2 Sensor 1 Heater Command

HO2S

On/Off

On

HO2S Bank 2 Sensor 1 Heater Command

HO2S

%

7-60

HO2S Bank 2 Sensor 2

Eng, FT, HO2S

mV

0-1,000

HO2S Bank 2 Sensor 2 Heater

HO2S

Amps

0.50-1.00

HO2S Bank 2 Sensor 2 Heater Circuit Status

HO2S

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

OK

HO2S Bank 2 Sensor 2 Heater Command

HO2S

On/Off

On

HO2S Bank 2 Sensor 2 Heater Command

HO2S

%

7-90

HO2S Heater Monitor Complete This Ignition

I/M

Yes/No

Varies

HO2S Heater Monitor Enabled This Ignition

I/M

Yes/No

Varies

HO2S/O2S Monitor Complete This Ignition

I/M

Yes/No

Varies

HO2S/O2S Monitor Enabled This Ignition

I/M

Yes/No

Varies

HOT Open Loop

FT, HO2S

Active/Inactive

Inactive

IAT Sensor

Eng, CMP, EVAP, FT, HO2S, Ign, Ind, I/M, Misfire, TAC

°C/°F

Varies

Ignition 1 Signal

Eng, CMP, EVAP, FT, HO2S, Ign, Ind, I/M, Misfire, TAC

Volts

12-14.5

Ignition Accessory Signal

Eng, TAC

On/Off

On

Ignition Off Time

I/M

min

Varies

Inj. 1 Disabled Due to Misfire

Misfire

Yes/No

No

Inj. 2 Disabled Due to Misfire

Misfire

Yes/No

No

Inj. 3 Disabled Due to Misfire

Misfire

Yes/No

No

Inj. 4 Disabled Due to Misfire

Misfire

Yes/No

No

Inj. 5 Disabled Due to Misfire

Misfire

Yes/No

No

Inj. 6 Disabled Due to Misfire

Misfire

Yes/No

No

Injector PWM Bank 1

Eng, FT, HO2S, Misfire

ms

1.85-2.05

Injector PWM Bank 2

Eng, FT, HO2S, Misfire

ms

1.85-2.05

Intake Manifold Pressure

FT, Ind

kPa

varies

Knock Detected Cyl. 1

Ign

Yes/No

No

Knock Detected Cyl. 2

Ign

Yes/No

No

Knock Detected Cyl. 3

Ign

Yes/No

No

Knock Detected Cyl. 4

Ign

Yes/No

No

Knock Detected Cyl. 5

Ign

Yes/No

No

Knock Detected Cyl. 6

Ign

Yes/No

No

Knock Retard

EGR, Ign

degrees

0

Long Term FT Bank 1

Eng, EVAP, FT, HO2S

%

0

Long Term FT Bank 2

Eng, EVAP, FT, HO2S

%

0

Loop Status

Eng, EVAP, FT, HO2S

Open/Closed

Closed

LT FT Test Avg. Bank 1

FT

%

1.00

LT FT Test Avg. Bank 2

FT

%

1.00

LT FT Test Avg. Bn 1 w/o purge

FT

%

0.98

LT FT Test Avg. Bn 2 w/o purge

FT

%

0.99

MAF Performance Test

FT, Ind, TAC

OK/Fault

OK

MAF Sensor

Eng, CMP, EVAP, FT, HO2S, Ign, Ind, Misfire, TAC

g/s

3-6 (varies with altitude)

MAF Sensor

Ind

Hz

1,200-1,300 (varies with altitude)

MAP Performance Test 1

FT, Ind, TAC

OK/Fault

OK

MAP Performance Test 2

FT, Ind, TAC

OK/Fault

OK

MAP Sensor

Eng, CMP, EVAP, FT, HO2S, Ign, Ind, Misfire, TAC

kPa

20-48 (varies with altitude)

MAP Sensor

Ind

Volts

0.4-2.0 (varies with altitude)

MIL Circuit Status

Eng

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

OK

MIL Command

Eng, I/M

On/Off

Off

MIL Requested by DTC

Eng, CMP, EVAP, FT, HO2S, Ign, Ind, I/M, Misfire, TAC

Yes/No

No

Misfire Current Cyl. 1

Misfire

Counts

0

Misfire Current Cyl. 2

Misfire

Counts

0

Misfire Current Cyl. 3

Misfire

Counts

0

Misfire Current Cyl. 4

Misfire

Counts

0

Misfire Current Cyl. 5

Misfire

Counts

0

Misfire Current Cyl. 6

Misfire

Counts

0

Misfire History Cyl. 1

Misfire

Counts

0

Misfire History Cyl. 2

Misfire

Counts

0

Misfire History Cyl. 3

Misfire

Counts

0

Misfire History Cyl. 4

Misfire

Counts

0

Misfire History Cyl. 5

Misfire

Counts

0

Misfire History Cyl. 6

Misfire

Counts

0

Power Enrichment

Eng, FT, HO2S, Misfire

Active/Inactive

Inactive

Reduced Engine Power

TAC

Active/Inactive

Inactive

Short Term FT Bank 1

Eng, EVAP, FT, HO2S

%

0

Short Term FT Bank 2

Eng, EVAP, FT, HO2S

%

0

Spark

Eng, FT, HO2S, Ign, Ind, Misfire

degrees

18-24

ST FT Test Avg. Bank 1

FT

%

0.98-1.00

ST FT Test Avg. Bank 2

FT

%

0.98-1.00

Start-up ECT

HO2S, I/M

°C/°F

Varies

Start-up IAT

HO2S, I/M

°C/°F

Varies

TAC Forced Engine Shutdown

TAC

Yes/No

No

TAC Motor

TAC

Enabled/Disabled

Enabled

TAC Motor Command

TAC

%

15-25

Torque Management Spark Retard

Ign

Degrees

0

Total Knock Retard

Ign

Degrees

0

Total Misfire

Misfire

Counts

0

TP Desired Angle

TAC

%

3

TP Indicated Angle

Eng, CMP, EVAP, FT, HO2S, Ign, Ind, Misfire, TAC

%

4

TP Performance Test

FT, Ind, TAC

OK/Fault

OK

TP Sensor 1

TAC

Volts

4.18

TP Sensor 1 Indicated Position

TAC

%

4

TP Sensor 1 Learned Minimum

TAC

Volts

0.63

TP Sensor 2

TAC

Volts

0.78

TP Sensor 2 Indicated Position

TAC

%

4

TP Sensor 2 Learned Minimum

TAC

Volts

0.63

TP Sensors 1 and 2

TAC

Agree/Disagree

Agree

Vehicle Speed Sensor

Eng, CMP, EVAP, FT, HO2S, Ign, Ind, I/M, Misfire, TAC

km/h /mph

0

Warm-ups Since DTC Cleared

Eng

Counts

Varies

Warm-ups w/o Emission Faults

Eng

Counts

Varies

Warm-ups w/o Non-Emission Faults

Eng

Counts

Varies

Wide Open Throttle

TAC

Yes/No

No