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 powertrain control module (PCM) 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 in engine controls section for diagnosis. The Typical Scan Data Values table contains all the parameters included in the following data lists arranged in alphabetical order:

    • Engine Data 1--Contains general information regarding fuel delivery and basic engine operating conditions.
    • Engine Data 2--Contains general information regarding air conditioning (A/C), crankshaft position (CKP), camshaft position (CMP), knock sensor (KS), and basic engine operating conditions.
    • Engine Data 3--Contains general information regarding fuel delivery, engine coolant temperature (ECT), idle air temperature (IAT), vehicle theft deterrent (VTD), and basic engine operating conditions.
    • Evaporative Emission (EVAP) Data--Contains information specific to the evaporative emissions (EVAP) control system. Also displays parameters required to verify proper EVAP system operation.
    • Fuel Trim Data--Contains specific information regarding fuel trim.
    • Misfire Data--Contains specific information regarding misfire diagnostics and parameters required to verify proper operation with regard to misfire.

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.

Typical Scan Tool Data List

Scan Tool Parameter

Data List

Units Displayed

Typical Data Value

A/C High Side Pressure

Engine 2

Volts

0-5.0 Volts

A/C High Side Pressure

Engine 2

kPa/psi

0-3100 kPa/0-450 psi (varies with the refrigerant pressure)

Another TWC Test Desired

Fuel Trim

Yes/No

No

A/C Relay Command

Engine 1

Engine 2

Engine 3

Misfire

ON/OFF

OFF (ON with the A/C requested)

A/C Request Signal

Engine 2

Yes/No

No (Yes with A/C ON)

Air Flow Calculated

Engine 1

Engine 2

Engine 3

Fuel Trim

Misfire

g/s

Varies

Air/Fuel Ratio

Engine 2

Engine 3

Fuel Trim

Ratio

14.6:1 (varies)

BARO

Engine 1

EVAP

Fuel Trim

kPa

65-104 (varies with the altitude and barometric pressure).

CKP Active Counter (7X Reference)

Engine 2

0-255 Counts

0-255--Increments while cranking or running

CMP Active Counter

Engine 2

0-255 Counts

0-255--Increments while cranking or running

CMP Resync Counter

Engine 2

0-255 Counts

0

Cruise Control Active

Engine 1

Engine 2

Engine 3

Yes/No

No

Cruise Release Clutch / TCC Pedal Switch

Engine 1

Engine 2

Engine 3

Applied/Unapplied

Unapplied

Current Gear

Engine 1

Engine 2

Fuel Trim

1-6

6

Cycles of Misfire Data

Misfire

Counts

0-99 (varies)

Desired Idle Speed

Engine 1

Engine 2

Engine 3

EVAP

RPM

PCM commanded idle speed (varies with calibration).

ECT Sensor

Engine 1

Engine 2

Engine 3

EVAP

Fuel Trim

Misfire

°C-°F

85°C-115°C/185°F-239°F (varies with coolant temperature).

Engine Load

Engine 1

Engine 2

Engine 3

EVAP

Fuel Trim

Misfire

%

11%-21%

16-29% at 2,500 RPM

Engine Oil Life Remaining

Engine 3

%

0-100% (varies)

Engine Oil Pressure Switch

Engine 3

Low/OK

OK (Low with low oil pressure)

Engine Run Time

Engine 1

Engine 2

Engine 3

EVAP

Fuel Trim

Misfire

Hr:Min:Sec

Depends on time since startup.

Engine Speed

Engine 1

Engine 2

Engine 3

EVAP

Fuel Trim

Misfire

RPM

±100 RPM from Desired Idle

EVAP Purge Solenoid Command

Engine 1

EVAP

Fuel Trim

%

0%-100% (varies)

EVAP Test Results

EVAP

Passed/No Result

No Result

EVAP Test Abort Reason

EVAP

Aborted/Not Aborted

Not Aborted

EVAP Test State

EVAP

Test Completed/Test Running

Test Running

EVAP Vent Solenoid Command

Engine 1

EVAP

Fuel Trim

Venting/Non-venting

Varies

FC Relay Command

Engine 2

Engine 3

ON/OFF

OFF (Varies with fan request)

Fuel Level Sensor

Engine 1

EVAP

%

0-100% Depends on fuel level

Fuel Pump Relay Command

Engine 1

ON/OFF

ON

Fuel Tank Pressure Sensor

Engine 1

EVAP

mm Hg/in H2O

Depends on Pressure/Vacuum

Fuel Tank Pressure Sensor

EVAP

Volts

Depends on Pressure/Vacuum

Fuel Trim Cell

Engine 1

EVAP

Fuel Trim

Cell number

18-21 at idle (Varies with the air flow, RPM P/N and A/C

Generator L Terminal Signal

Engine 2

Voltage/No Voltage

Voltage

Generator F Terminal Signal

Engine 2

%

0-100% (Varies)

HO2S 2

Engine 1

Fuel Trim

mV

0-1000, constantly varying

IAC Position

Engine 1

Fuel Trim

Counts

5-60

IAT Sensor

Engine 1

Engine 2

Engine 3

EVAP

Fuel Trim

°C-°F

10°-80°C (50°-176°F varies with under hood temperature)

Ignition 1 Signal

Engine 1

Engine 2

Engine 3

EVAP

Fuel Trim

Volts

12.0-15.0 Volts (Varies)

Injector PWM

Engine 2

Fuel Trim

Misfire

mS

3-4 mS

Injector 1 Command

Engine 3

mS

3-4 mS

Injector 2 Command

Engine 3

mS

3-4 mS

Injector 3 Command

Engine 3

mS

3-4 mS

Injector 4 Command

Engine 3

mS

3-4 mS

Knock Retard

Engine 1

Degrees

Long Term FT

Engine 1

Engine 2

Engine 3

EVAP

Fuel Trim

0% +/- 10-%

58-198 (-100%- to 100% varies)

Loop Status

Engine 1

Engine 2

Engine 3

EVAP

Fuel Trim

Open/Closed

Closed

MAP Sensor

Engine 1

Engine 2

Engine 3

EVAP

Fuel Trim

Misfire

kPa

25-48 kPa

MAP Sensor

Engine 1

Engine 2

Engine 3

Volts

1-3 volts (Varies with the vacuum and BARO pressure)

MIL Command

Engine 1

ON/OFF

OFF (with no codes)

Misfire Current #1-#4

Misfire

0-255 Counts

0 (increase with a misfire)

Misfire History #1-#4

Misfire

0-255 Counts

0 (increase with a misfire)

Med. Resolution Resync Counter

Engine 2

0-255 Counts

0

Number of DTCs

Engine 1

EVAP

Fuel Trim

Number

0

O2S 1

Engine 1

EVAP

Fuel Trim

mV

1-1000 and varying

Power Enrichment

Engine 2

Misfire

Active/Inactive

Inactive

Short Term FT

Engine 1

Engine 2

Engine 3

EVAP

Fuel Trim

%

0% +/- 10%

Spark

Engine 1

Engine 2

Engine 3

Fuel Trim

Misfire

Degrees

Varies

Start Up ECT

Engine 2

EVAP

Fuel Trim

°C-°F

Varies with start up temperature

TCC Enable Solenoid Command

Engine 1

Engine 2

Misfire

ON/OFF

ON

TP Sensor

Engine 1

Engine 2

EVAP

Fuel Trim

Misfire

%

0% (up to 100% at wide open throttle)

TP Sensor

Engine 1

Engine 2

Engine 3

Volts

0.200--0.900 volts (up to 5.0 volts at wide open throttle)

TR Switch

Engine 2

Engine 3

Fuel Trim

Low/High

Low/Low/High/High

TWC Temperature Calculated

Fuel Trim

°C-°F

Varies

Vehicle Speed Sensor

Engine 1

Engine 2

Engine 3

EVAP

Fuel Trim

Misfire

Km/h/MPH

0

VTD Fuel Disable

Engine 3

Active/Inactive

Inactive

VTD Auto. Learn Timer

Engine 3

Active/Inactive

Inactive