GM Service Manual Online
For 1990-2009 cars only
4WD Low: Displays Enabled or Disabled. This parameter is the signal state of the four-wheel drive low circuit. Enabled indicates a 0 voltage signal requested 4WD low. Disabled indicates a B+ voltage signal, which does not request 4WD low.

Cold Shift Pattern: Displays Enabled or Disabled. This parameter indicates whether the transmission is operating under a cold shift strategy.

Current Gear: Displays 1, 2, 3, 4, 5, or 6. This parameter indicates the current commanded state of the pressure control solenoids 1 and 2 and the state of the TFP switches 1, 2, 3, and 4.

Driver Demanded Engine Torque: Displays a range of 0-9,999 lb ft. This parameter indicates the amount of torque that is requested by throttle angle and driving conditions.

Engine Run Time: Displays a range of 0:00:00-18:12:15 hr/min/sec. This parameter measures the length of time the engine has been in operation during the present ignition cycle.

Engine Torque: Displays a range of 0-9,999 lb ft. This parameter is a calculated value based on engine load, throttle position, mass air flow, and other engine and transmission inputs. This parameter is accurate to within 15 lb ft of actual measured engine torque.

Gear Commanded: Displays a range of 0-8. This parameter indicates the commanded gear state from the transmission control module (TCM). When the vehicle is in the Neutral position this parameter displays 0. When the vehicle shift lever is placed in Drive, this parameter displays 1 while the vehicle is in first gear and changes accordingly as the vehicle shifts through 2, 3, 4, 5, and 6 This parameter displays 7 when reverse is commanded and 8 when the shift selector is in the park position.

Gear Ratio: Displays a range of 0.000 to 8.00:1. This parameter is the actual gear ratio of the current commanded gear. The gear ratio is calculated by dividing the turbine speed by the output speed.

Gear Selected: Displays a range of 0-8. This parameter indicates the selected state of the gear selector. Park = 8, Reverse = 7, Neutral = 0, Drive = 6, M = 1, 2, 3, 4, 5 or 6 selected by tap up, tap down feature, and 1 =1 as the gear selector is moved through the ranges.

Ignition Voltage: Displays a range of 0.0-25.5 Volts. This parameter indicates the voltage level on the ignition input to the TCM. The normal ignition voltage is approximately 13.8 volts, but may vary between 11-16 volts.

Last Output Speed Range Shift: Displays a range of 0-8,192 RPM. This parameter indicates the RPM value at which the last shift occurred.

Line PC Sol. Pressure Command: Displays a range of 0-232 psi. This parameter indicates the commanded line pressure.

Next Output Speed for Downshift: Displays a range of 0-8,192 RPM. This parameter indicates the RPM value at which the next output speed downshift will occur based on current driving requirements.

Next Output Speed Upshift: Displays a range of 0-8,192 RPM. This parameter indicates the RPM value at which the next output speed upshift will occur based on current driving requirements.

Normal Shift Pattern: Displays Enabled or Disabled. This parameter indicates the transmission is operating under a normal shift pattern strategy.

PC Sol. 1 Pressure Command: Displays a range of 0-232 psi. This parameter is the commanded pressure of pressure control solenoid 1.

PC Sol. 2 Pressure Command: Displays a range of 0-232 psi. This parameter is the commanded pressure of pressure control solenoid 2.

Previous Gear: Displays 0-7. This parameter displays the most recent gear the transmission has completed. During an upshift or downshift it continues to display the gear it was currently in until the new gear position has been successfully completed.

Requested Torque: Displays a range of 0-9,999 lb ft. This parameter indicates the amount of torque required by the driver.

Service Brake Status Inverted: Displays Enabled or Disabled. This parameter indicates the status of the brake switch. Enabled indicates that the brake pedal is not depressed. Disabled indicates that the brake pedal is depressed.

Shift Solenoid 1: Displays ON or OFF. This parameter is the commanded state of the shift solenoid 1 valve. On represents a commanded energized state, current is flowing through the solenoid. Off represents a non-commanded state, current is not flowing through the solenoid.

Shift Solenoid 2: Displays ON or OFF. This parameter is the commanded state of the shift solenoid 2 valve. On represents a commanded energized state, current is flowing through the solenoid. Off represents a non-commanded state, current is not flowing through the solenoid.

Shift Solenoid 3: Displays ON or OFF. This parameter is the commanded state of the shift solenoid 3 valve. On represents a commanded energized state, current is flowing through the solenoid. Off represents a non-commanded state, current is not flowing through the solenoid.

TCC PC Sol. Pressure Command: Displays a range of 0-160 psi. This parameter indicates the commanded TCC pressure.

TCC Slip Speed: Displays -4,080 to +4,079 RPM. This parameter is the difference between transmission input speed and engine speed. A negative value indicates the engine speed is less than the input speed, deceleration. A positive value indicates the engine speed is equal to the input speed, TCC applied.

TFP Switch 1: Displays ON or OFF. This parameter indicates the state of pressure switch 1 of the pressure switch module. ON represents a 0 voltage signal indicating that shift valve 1 is in the stroked position and OFF represents a 5 volt reference voltage signal indicating shift valve 1 is in the destroked position.

TFP Switch 2: Displays ON or OFF. This parameter indicates the state of pressure switch 2 of the pressure switch module. ON represents a 0 voltage signal indicating that shift valve 2 is in the stroked position and OFF represents a 5 volt reference voltage signal indicating shift valve 2 is in the destroked position.

TFP Switch 3: Displays ON or OFF. This parameter indicates the state of pressure switch 3 of the pressure switch module. ON represents a 0 voltage signal indicating that shift valve 3 is in the stroked position and OFF represents a 5 volt reference voltage signal indicating shift valve 3 is in the destroked position.

TFP Switch 4: Displays ON or OFF. This parameter indicates the state of pressure switch 4 of the pressure switch module. ON represents a 0 voltage signal indicating that the selector valve is in reverse and OFF represents a 5 volt reference voltage signal indicating the selector valve is neutral or a forward range.

Torque Management Duty Cycle: Displays in a percent of Duty Cycle. This parameter indicates the amount of torque management being used by the transmission control module (TCM).

Tow/Haul Mode: Displays Active/Inactive. This parameter indicates whether the driver has placed the vehicle in the Tow/Haul mode. When this parameter is active, the TCM modifies the shift strategy in order to provide more torque to the wheels during shifts.

TP Angle: Displays a range of 0-100 percent. The TP angle is computed by the PCM, from TP voltage. The TP angle should display 0 percent at idle and 100 percent at wide open throttle (WOT).

TR Sw.: Displays a range of Park, Reverse, Neutral, Drive, 5, 4, 3, 2, 1. The transmission range (TR) switch indicates the TR selected by the driver.

TR Sw. A/B/C/P: Displays ON/OFF, ON/OFF, ON/OFF, ON/OFF. These parameters are four inputs from the internal mode switch assembly. ON represents a 5 volt reference voltage signal. OFF represents a 0 voltage signal.

Trans. Fluid Temp.: Displays -40°C to +151°C (-40°F to +304°F). This parameter is the input signal of the transmission fluid temperature sensor. The transmission fluid temperature is high when the signal voltage is low, and the transmission fluid temperature is low when the signal voltage is high.

Transmission Hot Mode: Displays ON or OFF. This parameter monitors the transmission fluid temperature (TFT). Yes indicates the transmission fluid temperature has exceeded 135°C (275°F).

Transmission ISS: Displays 0-8,192 RPM. This parameter measures the rotational speed of the torque converter, same as the engine speed, expressed as revolutions per minute (RPM). In some cases, parameter data is provided by the ECM via the GMLAN.

Transmission OSS: Displays 0-8,192 RPM. This parameter measures the rotational speed of the transmission output shaft expressed as RPM. On four-wheel drive applications, the transfer case output shaft speed is measured.

Turbine Speed: Displays 0-8,192 RPM. This parameter indicates the rotational speed of the torque converter turbine shaft expressed as RPM.