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 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 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), intake 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 Volts

A/C High Side Pressure

Engine 2

kPa/psi

0-3,100 kPa (0-450 psi)

Varies with the refrigerant pressure

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/Released

Released

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

85-115°C/185-239°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 Abort Reason

EVAP

Aborted/Not Aborted

Not Aborted

EVAP Test Results

EVAP

Passed/No Result

No Result

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 1

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

mmHg/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

Fuel Trim Index

Fuel Trim

%

0% +/- 10%

Generator L Terminal Signal

Engine 2

ON/OFF

Varies

Generator F Terminal Signal

Engine 2

%

0-100%

Varies

HO2S 1

Engine 1

EVAP

Fuel Trim

mV

1-1,000, constantly Varying

HO2S 2

Engine 1

Fuel Trim

mV

0-1,000, constantly Varying

HO2S 1 Heater Command

Fuel Trim

ON/OFF

OFF

HO2S 2 Heater Command

Fuel Trim

ON/OFF

OFF

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

12-15 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

Power Enrichment

Engine 2

Fuel Trim

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 volts at wide open throttle

TR Switch

Engine 2

Engine 3

Fuel Trim

Park, Reverse, Neutral, Drive 4, 3, 2, 1

Park

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