GM Service Manual Online
For 1990-2009 cars only

Use the Typical Scan Data Values table only after the Powertrain On-Board Diagnostic System Check has been completed, no DTCs were noted and you have determined the on-board diagnostics are functioning properly. Scan tool values from a properly running engine may be used for comparison with the engine you are diagnosing. The Typical Scan Data values 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.

Important: Use the Typical Scan Data Values only after the following conditions are met:

    • The Powertrain On-Board Diagnostic System Check has been completed.
    • The engine is idling.
    • The engine is at operating temperature.
    • The throttle is closed.
    • The vehicle is in PARK or NEUTRAL.
    • The vehicle is operating in Closed Loop.
    • The vehicle accessories are turned OFF.

Typical Scan Tool Data Values

Scan Tool Parameter

Data List

Units Displayed

Typical Data Value

A/C High Side Pressure

Engine 2

Volts

Varies with refrigerant temperature

A/C Pressure Out of Range

Engine 2

Yes / No

No (Yes with low or high A/C refrigerant pressure)

A/C Relay

Output Driver

Fault / OK

OK

A/C Request

Engine 2

Yes / No

No (Yes with A/C requested

Actual EGR Position

Engine 1

Engine 2

EGR

Misfire

Percent

0%

Air/Fuel Ratio

Engine 1

Catalyst

HO2S

A.I.R

Ratio

14.2:1-14.7:1

A.I.R Active Test AIR Injection

A.I.R

Yes / No

Yes

A.I.R Active Test Inhibit

A.I.R

Yes / No

No

A.I.R Active Test Passed

A.I.R

Yes / No

Yes

A.I.R Passive Test Inhibit

A.I.R

Yes / No

Yes

A.I.R Passive Test in Progress

A.I.R

Yes / No

Yes

A.I.R Passive Test 1 Passed

A.I.R

Yes / No

Yes

A.I.R Passive Test 2 Fail

A.I.R

Yes / No

No

A.I.R Passive Test Passed

A.I.R

Yes / No

Yes

A.I.R Pump Relay

Engine 1

A.I.R

On / Off

Off

A.I.R Pump Relay

Output Driver

A.I.R

Fault / OK

OK

A.I.R Solenoid

Engine 1

A.I.R

On / Off

Off

A.I.R Solenoid

Output Driver

A.I.R

Fault / OK

OK

BARO

Engine 1

Engine 2

Catalyst

EVAP

EGR

kPa / Volts

65 - 110 kPa (Depends on altitude and barometric pressure)

Boost Solenoid

Engine 2

Percent

100%

Brake Switch

Engine 1

Engaged / Released

Released (Engaged with pedal depressed)

Cam Signal Present

Misfire

Yes / No

Yes

Change Oil Lamp

Engine 2

%

Displays remaining oil life

Change Oil Lamp

Output Driver

Fault / OK

OK

Commanded A/C

Engine 2

Catalyst

Misfire

On / Off

Off (On with A/C compressor engaged)

Commanded GEN

Engine 1

On / Off

On

Commanded Starter

Engine 2

Disabled / Enabled

Disabled

Cruise

Engine 1

Engaged / Disengaged

Disengaged

Cruise Inhibit

Engine 1

Yes / No

Yes

Cruise Inhibit

Output Driver

Fault / OK

OK

Cruise Inhibited Reason

Engine 1

Reason

Vehicle Speed

Current Gear

Engine 1

1 / 2 / 3 / 4

1

Cylinder # Injector CKT H / S

Output Driver

Fault / OK

OK

Decel Fuel Mode

Engine 1

Engine 2

Catalyst

HO2S

Misfire

Active / Inactive

Inactive

Desired EGR Position

Engine 1

Engine 2

EGR

Misfire

Percent

0%

Desired Idle Speed

Engine 1

Engine 2

EGR

RPM

PCM commanded idle speed (varies with temperature)

Driver Module 1 Status

Output Driver

Disabled / Enabled

Enabled

Driver Module 2 Status

Output Driver

Disabled / Enabled

Enabled

Driver Module 3 Status

Output Driver

Disabled / Enabled

Enabled

Driver Module 4 Status

Output Driver

Disabled / Enabled

Enabled

ECT

Engine 1

Engine 2

EGR

EVAP

Catalyst

HO2S

Misfire

A.I.R

°C, °F

85°C-105°C / 185°F-220°F (varies with temperature)

EGR Closed Valve Pintle Position

EGR

Volts

0.14-1.0 Volts

EGR Duty Cycle

EGR

Percent

0%

EGR Feedback

EGR

Volts

0.14-1.0 Volts

EGR Flow Test Count

EGR

Counts

0-10

EGR Position Error

EGR

Percent

0%-9%

Engine Hot Lamp

Engine 2

On / Off

Off

Engine Load

Engine 1

Engine 2

Catalyst

Misfire

A.I.R

Percent

Varies with Load

Engine Oil Level

Engine 2

OK / Low

OK

Engine Oil Life

Engine 2

Percent

0%-100% (varies)

Engine Oil Pressure

Engine 2

OK / Low

OK

Engine Run Time

Engine 1

Engine 2

Catalyst

EVAP

A.I.R

Hr: Min: Sec

Depends on time since startup

Engine Speed

Engine 1

Engine 2

EGR

EVAP

HO2S

Misfire

RPM

± 100 RPM from Desired Idle Speed

EVAP Canister Purge

EVAP

HO2S

A.I.R

Percent

0% - 25% (varies)

EVAP Fault History

EVAP

No Fault

No Test Result

Excess Vacuum

Purge Valve Leak

Small Leak

Weak Vacuum

No Fault

EVAP Purge Solenoid

Output Driver

Fault / OK

OK

EVAP Vent Solenoid

EVAP

Open / Closed

Open

EVAP Vent Solenoid

Output Driver

Fault / OK

OK

Fan High Speed

Engine 2

Catalyst

On / Off

Off (On with fan running)

Fan Low Speed

Engine 2

Catalyst

On / Off

Off (On with fan running)

FC Relay 1

Output Driver

Fault / OK

OK

FC Relay 2 and 3

Output Driver

Fault / OK

OK

Fuel Level

EVAP

Percent

0%-100% (varies)

Fuel Pump

Engine 2

On / Off

On

Fuel Pump Speed

Engine 2

Normal / High

Normal

Fuel Pump CKT Status

Output Driver

Fault / OK

OK

Fuel Pump CKT Hist.

Output Driver

Fault / OK

OK

Fuel Pump Speed (VIN 1)

Engine 2

Normal / High

Normal

Fuel Tank Pressure

EVAP

mmHg / Volts

-0.33 / -0.53 mmHg

1.46 / 1.49 Volts

Fuel Trim Cell

Engine 1

Misfire

A.I.R

Cell #

0

Fuel Trim Learn

Engine 1

Catalyst

Disabled / Enabled

Enabled

Generator Lamp

Engine 2

On / Off

Off

Generator PWM

Engine 2

Percent

Varies

HO2S Sensor 1

Engine 1

HO2S

Not Ready / Ready

Ready

HO2S Sensor 1

Engine 1

Catalyst

HO2S

A.I.R

Millivolts

0-1000 constantly varying

HO2S Sensor 2

Engine 1

Catalyst

HO2S

Millivolts

0-1000 constantly varying

HO2S XCounts

HO2S

Counts

Varies

IAC Position

Engine 1

Engine 2

Catalyst

EGR

Misfire

Counts

10-40

IAT

Engine 1

Engine 2

Catalyst

EVAP

HO2S

A.I.R

°C, °F

Varies with ambient air temperature

Ignition 1

Engine 1

Engine 2

EGR

HO2S

A.I.R

Volts

13 (varies)

Ignition Mode

Engine 2

IC / Bypass

IC

Injector Pulse Width

Engine 1

Catalyst

Milliseconds

1.5-3.5 (varies with engine load

Knock Retard

Engine 2

Degrees

0 degrees

Long Term FT

Engine 1

Misfire

A.I.R

Percent

-10%-10%

Loop Status

Engine 1

Catalyst

HO2S

Misfire

A.I.R

Open / Closed

Closed

Low Oil Lamp

Engine 2

On / Off

Off

MAF

Engine 1

Engine 2

Catalyst

HO2S

A.I.R

g/s

Varies (Depends on engine load and barometric pressure)

MAF Frequency

Engine 1

Hz

1200-3000 (Depends on engine load and barometric pressure)

MAP

Engine 1

Engine 2

EVAP

EGR

kPa / Volts

29-48 kpa / 1-2 volts (Depends on engine load and barometric pressure)

MIL

Engine 2

On / Off

Off

MIL

Output Driver

Fault / OK

OK

Misfire Current Cylinder #

Misfire

Counts

0-4

Misfire History Cylinder #

Misfire

Counts

0

Misfiring Cylinder (Primary / Secondary)

Misfire

0-6

0

Power Enrichment

Engine 1

Engine 2

Catalyst

HO2S

Misfire

Active / Inactive

Inactive

Rich/Lean Status

Engine 1

Rich / Lean

Constantly changing

Short Term FT

Engine 1

Catalyst

Misfire

A.I.R

Percent

-10%-10%

Spark

Engine 2

Degrees

20° (Varies)

Start Up ECT

EVAP

HO2S

A.I.R

°C, °F

Depends on engine coolant temperature at time of startup

Start Up IAT

EVAP

HO2S

A.I.R

°C, °F

Depends on engine ambient temperature at time of startup

TCC Solenoid

Output Driver

Fault / OK

OK

Throttle at Idle

Engine 1

Yes / No

Yes

Total Misfire Current Count

Misfire

Counts

0-5

Total Misfire Failures Since First Fail

Misfire

Counts

0

Total Misfire Passes Since First Fail

Misfire

Counts

0

TP Angle

Engine 1

Engine 2

Catalyst

EGR

EVAP

HO2S

Misfire

A.I.R

Percent

0%

TP Sensor

Engine 1

Volts

0.20-0.74

Traction Control

Engine 2

Active / Inactive

Inactive

Traction Control Desired

Engine 2

Percent

100%

Traction Control Torque

Engine 2

Percent

70%-80% (Varies with load)

Transmission Range

Engine 2

Park / Reverse / Neutral / Drive 4 / Driver 3 / Driver 2 / Low

Park

TR Switch P / A / B / C

Engine 2

High / Low

Low / Low / High / High

TWC Protection

Engine 1

Engine 2

Catalyst

HO2S

Misfire

Active / Inactive

Inactive

Vehicle Speed

Engine 1

Engine 2

EGR

EVAP

Catalyst

Misfire

mph / km/h

0

VTD Fuel Disable

Engine 2

Active / Inactive

Inactive

1 - 2 Solenoid

Output Driver

Fault / OK

OK

2 - 3 Solenoid

Output Driver

Fault / OK

OK

3X Crank Sensor

Misfire

RPM

Varies with Engine Speed

18X Crank Sensor

Misfire

RPM

Varies with Engine Speed