GM Service Manual Online
For 1990-2009 cars only

Scan Tool Parameter

Units Displayed

Cold Key On¹

Cold Idle¹

Hot Idle¹

89 km/h (55 MPH) Cruise²

AFO Signal

PCM/ AF ECM

Varies

AF ECM

AF ECM

AF ECM

AFO Signal Command

PCM/ AF ECM

Varies

AF ECM

AF ECM

AF ECM

AFO Enable Circuit Status

OK/Open/Shrt Ground/ Shrt Voltage

OK

OK

OK

OK

Alternative Fuel Level

%

Near gage reading

Near gage reading

Near gage reading

Near gage reading

Alternative Fuel Mileage Log

miles/ km

varies

varies

varies

varies

Alternative Fuel Run Time Log

Hours

varies

varies

varies

varies

Battery Voltage

Volts

within 1.5 volts of battery volts

within 1.5 volts of battery volts

within 1.5 volts of battery volts

within 1.5 volts of battery volts

ECT Sensor

°C (°F) / V

-20°C to 50°C

-20°C to 50°C

90°C to 110°C

90°C to 110°C

Engine Load

%

0%

1 to 5

1 to 5

13

Engine Run Time

Hr. / Min. / Sec.

0:00:00

Varies

Varies

Varies

Engine Speed

RPM

0

Within 80 RPM of Desired Idle

Within 80 RPM of Desired Idle

1700

EVAP Purge Solenoid Command

%

0%

Varies

Varies

Varies

EVAP Purge Solenoid Reduce Request Command

Normal/Reduce

Varies

Varies

Varies

Varies

EVAP Reduce Request Circuit Status

OK/Open/Shrt Ground/ Shrt Voltage

OK

OK

OK

OK

Fuel Control PWM Signal Command

%

Varies

Varies

Varies

Varies

Fuel Control Circuit Status

OK/Open/Shrt Ground/ Shrt Voltage

OK

OK

OK

OK

Fuel Gage Relay Command

Gasoline/ Alt. Fuel

AF

AF

AF

AF

Fuel Gage Select Switch

Released/ Depressed

Released

Released

Released

Released

Fuel Gage Circuit Status

OK/Open/Shrt Ground/ Shrt Voltage

OK

OK

OK

OK

Fuel Indicator Lamp Command

On/ Off

On two seconds then Off

Off

Off

Off

(Alt. Fuel) Fuel Pump Relay Command

On/Off

Off 2 seconds then On

On

On

On

Fuel Pressure Sensor

psi/ V

350 to 3600 psi

350 to 3600 psi

350 to 3600 psi

350 to 3600 psi

Fuel Temperature Sensor

°C (°F)/ V

near IAT

cooler than IAT

cooler than IAT

cooler than IAT

Gasoline Fuel Mileage Log

miles/ km

varies

varies

varies

varies

Gasoline Fuel Run Time Log

Hours

varies

varies

varies

varies

High Pressure Lockoff Relay Command

Flow/ No Flow

Flow 1 second then No Flow

Flow

Flow

Flow

HPL Solenoid Output Circuit Status

OK/Open/Shrt Ground/ Shrt Voltage

OK

OK

OK

OK

HO2S Bank 1 Sensor 1

mV

351 to 551 mV

Varies

Varying

Varying

HO2S Bank 2 Sensor 1

mV

351 to 551 mV

Varies

Varying

Varying

IAT Sensor

°C (°F) / V

near outside temp

near outside temp

underhood temp

underhood temp

Idle Fuel Control Solenoid PWM Command

%

Varies

Varies

Varies

Varies

Idle Control Circuit Status

OK/Open/Shrt Ground/ Shrt Voltage

OK

OK

OK

OK

Ignition 0

Volts

near battery volts

near battery volts

near battery volts

near battery volts

Long Term FT Avg.

%

0%

-25% to 25%

-25% to 25%

-25% to 25%

Loop Status

Open/ Closed

Open

Varies

Closed

Closed

Low Pressure Lockoff Solenoid Command

Flow/ No Flow

No Flow

Flow

Flow

Flow

LPL Solenoid Circuit Status

OK/Open/Shrt Ground/ Shrt Voltage

OK

OK

OK

OK

MAF Sensor

gms/sec - Hz

2.4 gms

9.8 -11.0 gms

5.0-7.0 gms

2-3 kHz

20-28 gms

MAP Sensor

kPa/ V

equal to barometric pressure

30 to 50 kPa

1.50 V @ 38 kPa

30 to 50 kPa

1.50 V @ 38 kPa

65 / 2.88

(Gasoline) MIL Command

Yes/No

Yes

No

No

No

(Alt. Fuel) MIL Command

On/ Off

On

Off

Off

Off

MIL Output CKT Status

OK/Open/Shrt Ground/ Shrt Voltage

OK

OK

OK

OK

Reference Voltage High

Volts

4.8 - 5.2

4.8 - 5.2

4.8 - 5.2

4.8 - 5.2

Reference Voltage Low

Volts

-0.2 - 0.2

-0.2 - 0.2

-0.2 - 0.2

-0.2 - 0.2

Short Term FT Avg.

%

0%

-5% to 5%

-8% to 8%

-10% to 10%

TP Sensor

Volts/%

0.55

0%

0.55

0%

0.55

0%

1.05

11%

Vehicle Speed Sensor

km/h (mph)

0

0

0

55 MPH

¹For Cold Key On, Cold Idle, and Hot Idle ensure the following driving conditions are met:

    • Vehicle in PARK
    • A/C turned OFF
    • No power steering load
    • All accessories OFF
    • Brake pedal released

²For 89 km/h (55 MPH) Cruise ensure the following driving conditions are met:

    • Vehicle in Drive
    • AC turned ON
    • No power steering load

Record the data after driving for approximately 1.6 km (1 mile).