GM Service Manual Online
For 1990-2009 cars only

The scan tool data definitions list contains a brief description of all transmission related parameters that are available on the scan tool. The list is arranged in alphabetical order. A given parameter may appear in any one of the data lists, or in more than one data list in order to group certain related parameters together. The Engine and Misfire data list, typical values and data definitions are covered in Engine Controls.

1-2/3-4 Solenoid -- Scan tool displays On/Off: This parameter is the commanded status of the 1-2/3-4 shift solenoid. On represents a commanded energized state (current flowing through the solenoid). Off represents a non-commanded state (current is not flowing through the solenoid).

2-3 Solenoid -- Scan tool displays On/Off: This parameter is the commanded status of the 2-3 shift solenoid. On represents a commanded energized state (current is flowing through the solenoid). Off represents a non-commanded state (current not flowing through the solenoid).

Accelerator Pedal Posit -- Scan tool displays a range of 0 to 100%: This parameter indicates the position of the accelerator pedal. The value indicated may not correspond to the TP angle valve.

Band Apply Solenoid -- Scan tool displays 0 to 100%: This parameter indicates the commanded duty cycle (DC) of the Band Apply Solenoid.

Battery Voltage -- Scan tool displays 0 to 18 Volts: This parameter is the battery voltage at the TCM.

Brake Switch -- Scan tool displays Applied/Released: Indicates the state of the Brake Switch. The TCM uses this input in order to control the TCC operation.

Commanded Gear-- Scan tool displays 1-2-3-4: This is the actual forward gear that is currently commanded by the TCM.

DTC #1: Scan tool displays current diagnostic trouble code set by the TCM.

DTC #2: Scan tool displays the second diagnostic trouble code set by the TCM. More than two codes can be set at one time by the TCM. Refer to DTC history.

Default Mode -- Scan tool displays Active/Inactive: Inactive indicates that the transmission is operating in normal modes. Active indicates that the transmission control system is operating in the default mode (all of the controlled components are de-energized).

ECT -- Scan tool displays: -40°C to 215°C (-40°F - 419°F): This value represents coolant temperature as sent over the ECM CAN data circuit.

Engine Speed -- Scan tool displays 0 to 8160 RPM: This is essentially a digital tachometer display. The engine speed is provided to the TCM from the ECM on the CAN data circuit.

Engine Torque -- Scan tool displays -100 to 410 N·m(-136 to +548 lb-ft): This value is proportional to engine torque. The ECM provides a torque output value to the TCM.

Engine Torque Reduction -- Scan tool displays -500 to +10 N·m(6.678-7.4 lb-ft): This parameter indicates the amount of torque reduction being requested. The value will decrease as the torque is reduced.

Hot Mode -- Scan tool displays Yes/No: This parameter monitors transmission temperature. Yes indicates that the transmission temperature has exceeded 165°C (329°F).

MIL Request -- Scan tool displays Active/Inactive: This is the current state of the MIL indicator lamp. Active indicates the TCM is requesting MIL illumination and the MIL should be on. Inactive indicates the TCM is not requesting MIL illumination.

Number of DTCs -- Scan tool displays 1-20: This indicates the actual quantity of DTCs stored in the TCM.

PC Sol. Actual Current 0.10 to 1.1 -- Scan tool displays .010 to 1.063 AMPS: This parameter is the actual current of the pressure control regulator solenoid circuit at the TCM. 0.10 AMPS (low current flow) indicates that the maximum line pressure is being commanded. 1.1 amps (high current flow) indicates that the minimum line pressure is being commanded.

PRNDL A -- Scan tool displays High/Low: This parameter is the input from the automatic transmission mode switch. High represents a B+ voltage signal and low represents a 0 voltage signal.

PRNDL B -- Scan tool displays High/Low: This parameter is the input from the automatic transmission mode switch. High represents a B+ voltage signal and low represents a 0 voltage signal.

PRNDL C -- Scan tool displays High/Low: This parameter is the input from the automatic transmission mode switch. High represents a B+ voltage signal and low represents a 0 voltage signal.

PRNDL P -- Scan tool displays High/Low: This parameter is the input from the automatic transmission mode switch. High represents a B+ voltage signal and low represents a 0 voltage signal.

Power Relay Status -- Scan tool displays On/Off: Indicates the commanded state of the relay output circuit. Active indicates the TCM is commanding the relay On (circuit voltage high). Inactive indicates the TCM is commanding the relay Off.

STL -- Scan tool displays On/Off: In early production vehicles, this display indicates the commanded state of the service transmission lamp.

Shift Pattern Mode: The scan tool displays the following modes:

    • Economy Program -- A manually selectable transmission mode (also the default mode at start up). Provides smooth shifts and shift scheduling tailored for fuel economy.
    • Sport Program -- A manually selectable transmission mode. The Sport Program provides firmer/delayed upshifts a for more aggressive performance.
    • Winter Program -- A manually selectable transmission mode. In this mode the transmission will start in 3rd gear in order to improve the traction during slippery conditions.
Sport Mode Lamp -- Scan tool displays On/Off: This display indicates the commanded state of the sport indicator lamp. In late production vehicles, the value will toggle rapidly when a DTC is set.

Sport Mode Switch -- Scan tool displays On/Off: This display indicates the state of the sport program push button. When you depress the button, this parameter will display On.

TCC Slip Speed -- Scan tool displays a range of -4064 to +4064 RPM: This parameter is the difference between transmission output speed and engine speed. A negative value indicates that the engine speed is less than the output speed (deceleration). A positive value indicates that the engine speed is greater than the output speed (acceleration). A value of zero indicates that the engine speed is equal to the output speed (TCC applied).

TCC Solenoid -- Scan tool displays On/Off: This parameter is the commanded state of the TCC solenoid. On indicates a commanded energized state (current flowing through the solenoid). Off indicates a commanded non-energized state (current not flowing through the solenoid).

TCM Torq. Red. Request -- Scan tool displays Yes/No: Yes indicates that the transmission is requesting the ECM to reduce the engine torque. No indicates engine torque reduction is not being requested.

TFT Sensor -- Scan tool displays: 0 to 5 Volts: This is the actual voltage on the TFT sensor signal circuit to the TCM as measured by the TCM. The value indicated may not correspond to the accelerator pedal posit value.

TP Angle -- Scan tool displays a range of 0-100%: This parameter indicates the amount of throttle opening.

TR Switch -- P/A/B/C: Scan tool displays On/Off: These parameters are the four inputs from the automatic transmission mode switch assembly. On represents a 0 voltage signal. Off represents a B+ voltage signal.

Trans. Fluid Temp. -- Scan tool displays: -40 to 215°C (-40° to 419°F): Display shows the temperature of the transmission fluid.

Transmission OSS -- Scan tool displays 0 to 8160 RPM: This parameter indicates the rotational speed of the transmission output shaft expressed as revolutions per minute.

Transmission Range -- Scan tool displays Park, Reverse, Neutral, Drive, 3rd, 2nd, 1st: Indicates the transmission selector lever position.

Vehicle Speed -- Scan tool displays a range of 0-248 km/h (0-158 mph): This parameter is the input signal from the vehicle speed sensor assembly to the TCM.

WOT Switch -- Scan tool displays On/Off: This parameter monitors wide open throttle requests from the ECM. On indicates that the accelerator pedal has been depressed beyond 89%.

Winter Mode Lamp -- Scan tool displays On/Off: This display indicates the commanded state of the winter indicator lamp.

Winter Mode Switch -- Scan tool displays On/Off: This display indicates the state of the winter mode push button. When then button is depressed this parameter will display on.