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, and in some cases may appear more than once, 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 (the 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 (the current is flowing through the solenoid). Off represents a non-commanded state (current not flowing through the solenoid).

A/C Request -- Scan tool displays Yes/No: This parameter indicates that the A/C has been requested and therefore the idle air, as commanded by the ECM, has been increased.

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

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

Calc. Pressure -- Scan tool displays 0 to 2550 kPa: The TCM uses various data parameters including the commanded Pressure Control Solenoid duty cycle in order to calculate the line pressure.

Cruise -- Scan tool displays Active/ Inactive: Displays the current state of the Cruise Control System.

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).

Desired Power Relay -- 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).

Desired Torque -- Scan tool displays 0 to 100%: This parameter indicates 100% during conditions when the torque reduction is not being requested. The value will decrease as the torque is reduced under certain operating conditions.

ECT -- Scan tool displays: 2 to 86%: This value represents coolant temperature as sent over the PWM encoded ECM Data Input 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 a dedicated line.

Engine Torque -- Scan tool displays 9 to 92%: This value is proportional to engine torque. The ECM provides a torque output value to the TCM.

MIL Request -- Scan tool displays Active/Inactive: The TCM has no direct control of the engine MIL, but if a transmission fault occurs that is emissions related, the engine MIL must illuminate. A MIL Request circuit between the ECM and the TCM provides a means for illuminating the MIL, even though the fault was detected by the TCM. This parameter indicates the state of this circuit as commanded by the TCM. Active indicates signal voltage low (MIL Requested), Inactive indicates signal voltage high.

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

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

Park/Neutral Info To ECM -- Scan tool displays Yes/No: This parameter indicates the state of the Transmission Range Selector as perceived by the ECM. Yes displays whenever Park or Neutral are selected, while any selector position will display No.

PC Solenoid -- Scan tool displays 100 to 1099 mA: This parameter is the actual current of the pressure control regulator solenoid circuit at the TCM. 100 milliamps (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.

Power Relay Status -- Scan tool displays On/Off: Indicates the actual state of the relay output circuit. Active indicates on (high).

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.
    • Warm-up Program 1 -- In order to quickly warm-up the vehicle catalyst, this mode is activated on the engine start with the engine temperature lower than 30°C and the vehicle speed is lower than 5 km/h. Activated for a driving time of approximately 1 minute, this mode is similar to performance mode. The upshiftd are delayed when compared to the economy mode.
    • Uphill Mode 1 -- The Uphill Mode 1 is activated depending on the vehicle load and the road load. The example is towing a trailer or when driving up a slight grade. Shift lines mainly affected are 3-4/4-3, 2-3/3-2, 1-2/2-1.
    • Downhill Mode 1 -- The Downhill Mode is activated when the vehicle descends a grade. Additional engine braking is provided by modifying the 3-4/4-3 and 2-3/3-2 shift lines
Sport Mode Lamp -- Scan tool displays On/Off: This display indicates the commanded state of the Sport Indicator Lamp. If the Sport Indicator Lamp and the display do not agree, go to the Sport Indicator Lamp Diagnosis table.

Sport Mode Switch -- Scan tool displays On/Off: This display indicates the perceived state of the Program Push Button. When you depress the button, this parameter will display On.

STL -- Scan tool displays Active/Inactive: This display indicates the commanded state of the Service Transmission Lamp (STL). If the STL and the display do not agree, go to the STL Diagnosis table.

TCC Solenoid -- Scan tool displays On/Off: This parameter is the commanded state of the TCC solenoid. Active indicates a commanded energized state (current flowing through the solenoid). Inactive 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.

Torque Factor TCM/EBTCM -- Scan tool displays 9 to 92%: This parameter displays the gear position signal output received by the Electronic Brake and Traction Control Module (EBTCM) from the TCM. When the vehicle speed is 0 and the Trans. Range Selector is in Park or Neutral, the signal output is around 9, while in R, D, 3, 2, or 1 the signal output is around 30%. When the vehicle speed is greater than 0, and the vehicle is shifting through its gear range, the signal output is typically 23% in 1st gear , 21% in 2nd gear, 16% in 3rd gear, and 14% in 4th gear.

TP Load Signal -- Scan tool displays: 8 to 93%: This value represents throttle position as sent over the PWM encoded ECM Data Input Circuit.

Trans. Fluid Temp -- 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.

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

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

WOT Switch -- Scan tool displays On/Off: This is the current state of the Throttle Switch. Active indicates that the throttle depresses beyond the equivalent of approximately 80% throttle angle.

Winter Mode Lamp -- Scan tool displays Active/Inactive: This display indicates the commanded state of the Winter Indicator Lamp. If the Winter Indicator Lamp and the display do not agree, go to the Winter Indicator Lamp Diagnosis table.

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