GM Service Manual Online
For 1990-2009 cars only
Table 1: At-1 Data List
Table 2: At-2 Data List

If you have completed the On-Board Diagnostic (OBD) system check, if the diagnostics are functioning properly and if no DTCs display, you may use the Typical Scan Values in the table below for comparison. These typical values are an average of display values recorded from normally operating vehicles. They represent the display from a normally functioning system.

You should never use a scan tool that displays faulty data. The condition should be reported to the manufacturer. The use of a faulty scan tool can result in misdiagnosis and the unnecessary replacement of parts.

Only the parameters listed below are used in this manual for diagnosing. If a scan tool displays other parameters, the values are not recommended by General Motors for use in diagnosis.

Scan tests are performed under the following driving conditions:

    • Engine idling
    • Upper radiator hose is hot
    • Closed throttle
    • Transmission is in Park
    • Closed Loop
    • Accessories OFF

At-1 Data List

Tech 2 Parameter

Units Displayed

Typical Scan Values

Engine Torque

N·m (lb ft)

Varies

TP Sensor

Volts

0.59V

TP Angle

Percent applied

0%

Engine Speed

RPM

610 RPM

Transmission ISS

RPM

680 RPM

Turbine Speed

RPM

680 RPM

Transmission OSS

RPM

0

Vehicle Speed

km/h (mph)

0

Commanded Gear

1,2,3,4

1

1-2 Sol.

ON/OFF

ON

2-3 Sol.

ON/OFF

OFF

Gear Ratio

Ratio

400:1

1-2 Sol. Open

Yes/No

No

1-2 Sol. Shorted

Yes/No

No

2-3 Sol. Open

Yes/No

No

2-3 Sol. Shorted

Yes/No

No

TFP Switch A/B/C

ON/OFF

OFF/ON/OFF

Trans. Fluid Temp.

°C (°F)

65°C (149°F)

TFT Sensor

Volts

3.02 Volts


At-2 Data List

Tech 2 Parameter

Units Displayed

Typical Scan Values

ECT

°C (°F)

83°C (181°F)

TFT Sensor

Volts

3.02V

Hot Mode

Yes/No

No

PC Act. Current

amps

0.96 amps

PC Ref. Current

amps

0.96 amps

PC Sol. Duty Cycle

Percent on time

57%/Varies

TCC Brake Switch

Open/Closed

Closed

TCC Duty Cycle

%

0%

TCC Slip Speed

RPM

-70 Varies

TCC Duty Cycle Open

Yes/No

No

TCC Duty Cycle Shorted

Yes/No

No

Last Shift Time

Seconds

Varies

1-2 Shift Time

Seconds

Varies

2-3 Shift Time

Seconds

Varies

3-4 Shift Time

Seconds

Varies

Adaptable Shift

Yes/No

No

Engine Run Time

Hr:Min:Sec

00:00:00

Ignition Voltage

Volts

13.5-14.5

Cruise

ENABLED/DISABLED

DISABLED

A/C Clutch

Yes/No

No

4WD

ENABLED/DISABLED

DISABLED

4WD Low

ENABLED/DISABLED

DISABLED