Transmission Control Module Scan Tool Information

The Transmission Control Module Scan Tool Data List contains 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 values below represent a typical display recorded from a properly functioning system.

NOTE:

Do not use a scan tool that displays faulty data. Report the condition to the scan tool manufacturer. The use of a faulty scan tool can result in misdiagnosis and the unnecessary replacement of components.

Only the parameters listed below are used/referenced in this service information for diagnosis. If a scan tool displays other parameters, those values are not recommended by General Motors for use in diagnosis.

If all values are within the expected value described below, refer to Symptoms - Automatic Transmission for diagnosis.

The scan tool values from a properly functioning transmission may be used for comparison with the transmission you are diagnosing. The values below represent a typical display recorded from a properly functioning system.

Scan Tool Data Parameters

Parameter	System State	Expected Value	Description
Operating Conditions: Engine at idle, upper radiator hose hot, closed throttle, transmission in Park, closed loop operation, accessories OFF, brake pedal not applied.
Actual Line Pressure Control Solenoid Valve Current	Varies	mA	This parameter displays the actual current being used by the Line Pressure Solenoid Valve. The Line Pressure Control Solenoid Valve is also known as the Pressure Control Solenoid 1 Valve. The scan tool displays current flow in milliamperes (mA). A reading of 0 mA, no current flowing, indicates low line pressure. A reading of 1000 mA (1.000 ampere), high current flow, indicates high pressure.
Actual Pulley Gear-Ratio	Varies	Ratio	This parameter displays the actual pulley gear-ratio.
Actual TCC Pressure Control Solenoid Valve Current	Varies	mA	This parameter displays the actual current being used by the Torque Convertor Clutch (TCC) Pressure Control Solenoid Valve. The scan tool displays current flow in milliamperes (mA). A reading of 0 mA, no current flowing, indicates low line pressure. A reading of 1000 mA (1.000 ampere), high current flow, indicates high pressure.
Automatic Braking Active Signal	Released	Applied/Released	This parameter displays the reception status of the stop lamp switch signal received through CAN communication.
Brake Pedal Switch	Released	Applied/Released	This parameter displays the status of the brake switch circuit input. Applied indicates a zero voltage input, brake pedal applied. Released indicates a voltage input, brake pedal released. The scan tool displays Applied or Released.
Calculated Line Pressure	Varies	kPa	This parameter displays a calculated line pressure used by the Line Pressure Solenoid Valve.
Calculated Throttle Position	Varies	%	This parameter displays a calculated value based off accelerator pedal position and actual throttle position. It represents the driver's intended request for torque or acceleration. The range is 0 - 100%, where 0% represents an idle or coast request and 100% represents a request for wide open throttle (WOT).
Calculated Vehicle Speed	-	-	This parameter calculates the speed at which the vehicle is traveling as kilometers per hour (km/h) or miles per hour (MPH). The transmission control module (TCM) calculates vehicle speed based on the input signal from the vehicle/output shaft speed sensor.
Clutch Slip Speed	Varies	RPM	This parameter displays the amount of torque converter clutch (TCC) slip between the engine and the transmission input shaft. A negative value indicates that the engine speed is less than the input speed, deceleration. A positive value indicates that the engine speed is greater than the input speed, acceleration. A value of zero indicates that the engine speed is equal to the input speed, TCC applied.
Control Module Voltage Signal	Varies	Volts	This parameter displays the system voltage measured by the transmission control module (TCM) at the TCM ignition voltage input circuit.
Engine Speed	Varies	RPM	This parameter displays the rotational speed of the engine expressed as revolutions per minute. This parameter value is determined by the engine control module and communicated to the TCM through the High Speed GMLAN Serial Data link.
Engine Speed Signal	Varies	RPM	This parameter displays the rotational speed of the engine expressed as revolutions per minute. This parameter value is determined by the engine control module and communicated to the TCM through the High Speed GMLAN Serial Data link.
Engine Torque	Varies	(N m)	This parameter displays the estimated amount of torque that is being delivered from the engine. The ECM calculates this value based on engine load, throttle position, mass air flow, and other engine inputs. The ECM communicates this value to the TCM through the High Speed GMLAN Serial Data link.
Gear Ratio	Varies	Ratio	This parameter displays the actual transmission gear ratio. The scan tool displays the gear ratio calculated from the automatic transmission (AT) input speed sensor (ISS) and the automatic transmission (AT) output speed sensor (OSS) inputs.
Ignition Voltage	9 - 19	Volts	This parameter displays the system voltage measured by the transmission control module (TCM) at the TCM ignition voltage input circuit.
Line Pressure Control Solenoid Valve Current	Varies	mA	This parameter displays the current the transmission control module (TCM) is sending to the Line Pressure Control Solenoid Valve. The scan tool displays current flow in milliamperes (mA). A reading of 0 mA, no current flowing, indicates low line pressure. A reading of 1000 mA (1.000 ampere), high current flow, indicates high pressure. The Line Pressure Solenoid Valve is also known as the Line Pressure Control Solenoid Valve or the Pressure Control Solenoid Valve 1.
Primary Pulley Speed	Varies	RPM	This parameter displays the rotational speed of the Primary Pulley expressed as revolutions per minute. This parameter value is determined by the Primary Pulley/Input Speed Sensor.
Primary Pulley Speed	Varies	V	This parameter displays the voltage sent to the primary pulley pressure sensor.
Pulley Gear-Ratio Command	Varies	Ratio	This parameter displays the commanded transmission gear ratio. The scan tool displays the gear ratio calculated from the automatic transmission (AT) input speed sensor (ISS) and the automatic transmission (AT) output speed sensor (OSS) inputs.
Secondary Pulley Pressure	Varies	kPa (psi)	This parameter displays the actual pressure at the secondary pulley. This is the same as line pressure.
Secondary Pulley Pressure Sensor	Varies	Volts	This parameter displays the voltage sent to the secondary pulley pressure sensor.
Secondary Pulley Speed	Varies	RPM	This parameter displays the rotational speed of the Secondary Pulley expressed as revolutions per minute. This parameter value is determined by the Secondary Pulley/Intermediate Shaft Speed Sensor.
TCC Pressure Control Solenoid Valve	Varies	kPa (psi)	This parameter displays the actual pressure at the TCC Pressure Control Solenoid Valve.
TCC Pressure Control Solenoid Valve	Varies	mA	This parameter displays the actual current being used by the Torque Convertor Clutch (TCC) Pressure Control Solenoid Valve. The scan tool displays current flow in milliamperes (mA). A reading of 0 mA, no current flowing, indicates low line pressure. A reading of 1000 mA (1.000 ampere), high current flow, indicates high pressure.
Throttle Position Command	Varies	%	This parameter displays a commanded value based off accelerator pedal position. It represents the driver's intended request for torque or acceleration. The range is 0 - 100%, where 0% represents an idle or coast request and 100% represents a request for wide open throttle (WOT).
Torque Converter Efficiency	Varies	Ratio	This parameter displays when the torque converter clutch is engaging and eliminating slip of the converter.
Torque Delivered Signal	Varies	(N m)	This parameter displays when the torque converter is commanded on, pushing the torque converter clutch piston for engagement.
Transmission Fluid Temperature	Varies	°C (°F)	This parameter displays the temperature of the transmission. Transmission fluid temperature is high 151°C (304°F) when signal voltage is low, 0 V, and transmission fluid temperature is low -40°C (-40°F) when signal voltage is high, 2.5 V.
Transmission Fluid Temperature Sensor	Varies	Volts	This parameter displays the input signal of the transmission fluid temperature sensor. Transmission fluid temperature is high 151°C (304°F) when signal voltage is low, 0 V, and transmission fluid temperature is low -40°C (-40°F) when signal voltage is high, 2.5 V.
Transmission Input Speed	Varies	RPM	This parameter displays the rotational speed of the transmission primary pulley speed (side cover of transaxle). The scan tool displays primary pulley speed in revolutions per minute (RPM).
Transmission ISS	Varies	RPM	This parameter displays the rotational speed of the transmission input shaft speed (front side of transaxle case). The scan tool displays input shaft speed in revolutions per minute (RPM).
Transmission OSS	Varies	RPM	This parameter displays the rotational speed of the transmission output shaft/final gear (back side of transaxle). The scan tool displays output shaft speed in revolutions per minute (RPM).
Transmission Range Switch	Park	Park, Reverse, Neutral, Drive, Low or Invalid	This parameter displays the current position of the transmission range switch.
Wheel Speed Signal	Varies	km/h (MPH)	This parameter displays the vehicle speed signal (ABS) at which the vehicle is traveling, received through CAN communication as kilometers per hour (km/h) or miles per hour (MPH).

Scan Tool Output Controls

Output Control	Description
Automatic Braking Active Signal	The TCM resets the engine braking with the engine braking adjustment. ON: Turns ON the engine brake control. OFF: Turns OFF the engine brake control.
Transmission Oil Life Reset	The TCM resets the amount of oil life remaining to 100 percent. There are not limits to using this output control. It may be performed with the engine running or when the ignition is ON or OFF.