Transmission Control Module Scan Tool Information (Allison)

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Scan Tool Data Parameters

Parameter	Expected Value	Description
Operating Conditions: Engine is at Idle, Upper Radiator Hose is Hot, Closed Throttle, Gear is in PARK, and Accessories are OFF.
Calculated Engine Torque	Y (lb ft)	Displays a range of 0-9,999 lb ft. This parameter indicates the calculated engine torque provided by the ECM via GM LAN. 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.
Calculated Throttle Position	%	Displays a range of 0-100%. This parameter indicates the percent throttle provided by the ECM via GM LAN. In the cases where the transmission ISS is not supplied by the ECM and the TCM loses communication with the ECM, the TCM will calculate the throttle position based on converter slip speed. In all other instances, the Calculated Throttle Position will default to a value that is TCM calibration dependent.
Current Gear	0-7	Displays 0, 1, 2, 3, 4, 5, 6, or 7. This parameter indicates the current transmission range attained as determined by the gear ratio.
Driver Demanded Engine Torque	Nm (lb ft)	Displays a range of 0-13,557 Nm (0-9,999 lb ft). This parameter indicates the amount of torque that is requested by the throttle position and driving conditions.
Driver Shift Control Mode	Inactive/Active	Displays Active or Inactive. This parameter indicates if the shift selector is in the manual mode position.
Driver Shift Request	Upshift / Downshift None / Invalid	Displays Upshift, Downshift, None, Invalid. This parameter displays the current request from the Tap Up/Tap Down switch system provided by the BCM via GM LAN. This parameter will display Upshift, Downshift, None, or Invalid depending on the amount of voltage measured.
Engine Run Time	Hr:Min:Sec	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.
Gear Command	0-8	Displays a range of 0-8. This parameter indicates the commanded gear state from the 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	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.
Ignition Voltage	V	Displays a range of 0.0-25.5 V. This parameter indicates the voltage level on the ignition input to the TCM. The normal ignition voltage is approximately 13.8 V, but may vary between 11-16 V.
Line Pressure Control Solenoid Valve Pressure Command	kPa (psi)	Displays a range of 1,600 kPa (0-232 psi). This parameter indicates the line pressure control solenoid valve commanded pressure. When the line pressure control solenoid valve is commanded ON, pressure from the line pressure control solenoid valve is directed to the line pressure regulator valve, which lowers the line pressure.
Pressure Control Solenoid Valve 1	kPa (psi)	Displays a range of 1,600 kPa (0-232 psi). This parameter is the commanded pressure of pressure control solenoid valve 1 which is directed through one or more of the shift valves to apply a clutch.
Pressure Control Solenoid Valve 2 Pressure Command	kPa (psi)	Displays a range of 1,600 kPa (0-232 psi). This parameter is the commanded pressure of pressure control solenoid valve 2 which is directed through the one or more of the shift valves to apply a clutch.
Requested Torque	Nm (lb ft)	Displays a range of 13,557 Nm (0-9,999 lb ft). This parameter indicates the amount of torque required by the driver.
Shift Solenoid Valve 1	On/Off	Displays On or Off. This parameter is the commanded state of the shift solenoid valve 1. On represents a commanded energized state, current is flowing through the solenoid valve. Off represents a non-commanded state, current is not flowing through the solenoid valve.
Shift Solenoid Valve 1 Debris Cleaning Command	Numeric Value	Displays a range of 0-255. This parameter indicates the number of times shift valve 1 did not stroke or destroke within a calibration dependent length of time after shift solenoid valve 1 was commanded ON or OFF.
Shift Solenoid Valve 1 Debris Cleaning Command	Disabled/Exhausted/Pressurized	This parameter indicates the override commanded state of shift solenoid valve 1 when debris cleaning of shift valve 1 is commanded.
Shift Solenoid Valve 2	On/Off	Displays ON or OFF. This parameter is the commanded state of shift solenoid valve 2. On represents a commanded energized state, current is flowing through the solenoid valve. Off represents a non-commanded state, current is not flowing through the solenoid valve.
Shift Solenoid Valve 2 Debris Cleaning Command	Numeric Value	Displays a range of 0-255. This parameter indicates the number of times shift valve 2 did not stroke or destroke within a calibration dependent length of time after shift solenoid valve 2 was commanded ON or OFF.
Shift Solenoid Valve 2 Debris Cleaning Command	Disabled/Exhausted/Pressurized	This parameter indicates the override commanded state of shift solenoid valve 2 when debris cleaning of shift valve 2 is commanded.
Shift Solenoid Valve 3	On/Off	Displays ON or OFF. This parameter is the commanded state of the shift solenoid valve 3. On represents a commanded energized state, current is flowing through the solenoid valve. Off represents a non-commanded state, current is not flowing through the solenoid valve.
Shift Solenoid Valve 3 Debris Cleaning Command	Numeric Value	Displays a range of 0-255. This parameter indicates the number of times shift valve 3 did not stroke or destroke within a calibration dependent length of time after shift solenoid valve 3 was commanded ON or OFF.
Shift Solenoid Valve 3 Debris Cleaning Command	Disabled/Exhausted/Pressurized	This parameter indicates the override commanded state of shift solenoid valve 3 when debris cleaning of shift valve 3 is commanded.
TCC Pressure Control Solenoid Valve Command	kPa (psi)	Displays a range of 0-160 psi. This parameter indicates the commanded TCC pressure.
TCC Slip Speed	RPM	Displays -4,080 to +4,079 RPM. This parameter is the difference between the engine speed and transmission turbine speed. A negative value indicates the engine speed is less than the turbine speed, deceleration. A positive value indicates the engine speed is greater than the turbine speed.
Transmission Fluid Pressure Switch 1	On/Off	Displays ON or OFF. This parameter indicates the state of transmission fluid pressure switch 1 of the transmission fluid pressure switch, also known as the pressure switch manifold. ON represents a 0 voltage signal indicating that shift valve 1 is in the stroked position and OFF represents a reference voltage signal indicating shift valve 1 is in the destroked position.
Transmission Fluid Pressure Switch 2	On/Off	Displays ON or OFF. This parameter indicates the state of transmission fluid pressure switch 2 of the transmission fluid pressure switch, also known as the pressure switch manifold. ON represents a 0 voltage signal indicating that shift valve 2 is in the stroked position and OFF represents a reference voltage signal indicating shift valve 2 is in the destroked position.
Transmission Fluid Pressure Switch 3	On/Off	Displays ON or OFF. This parameter indicates the state of transmission fluid pressure switch 3 of the transmission fluid pressure switch, also known as the ressure switch manifold. ON represents a 0 voltage signal indicating that shift valve 3 is in the stroked position and OFF represents a reference voltage signal indicating shift valve 3 is in the destroked position.
Transmission Fluid Pressure Switch 4	On/Off	Displays ON or OFF. This parameter indicates the state of transmission fluid pressure switch 4 of the transmission fluid pressure switch, also known as the pressure switch manifold. ON represents a 0 voltage signal indicating that the selector valve is in reverse and OFF represents a reference voltage signal indicating the selector valve is in neutral or a forward range.
Tow/Haul Mode	Inactive/Active	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 by raising the shift points and applying the TCC in lower ranges.
TP Angle	Percent	Displays a range of 0-100 percent. The TP angle is computed by the ECM, from throttle position voltage. The TP angle should display 0 percent at idle and 100 percent at wide open throttle (WOT).
Transmission Range Switch	Park, Reverse, Neutral, Drive, 5,4,3,2,1	Displays a range of Park, Reverse, Neutral, Drive, 5, 4, 3, 2, 1. The transmission range switch indicates the transmission range selected by the driver.
Transmission Range Switch A/B/C/P	On/Off	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.
Transmission Fluid Temperature	°C (°F)	Displays -40°C to +158°C (-40°F to +316°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	On/Off	Displays ON or OFF. When ON, the TCM changes the shift pattern which will increase engine speed to increase cooler flow.
Transmission ISS	RPM	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	RPM	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	RPM	Displays 0-8,192 RPM. This parameter indicates the rotational speed of the torque converter turbine shaft expressed as RPM.

Scan Tool Output Controls

Output Control	Description
Shift Solenoid Valve 1, 2, and 3	The TCM commands the shift solenoid valve ON and OFF. The scan tool shift solenoid valve parameter should match the commanded state. The scan tool Commanded Gear parameter should correspond with the shift solenoid valve combination. Refer to Solenoid and Clutch Chart (PCS1, PCS2, SS1, SS2, and SS3)Solenoid and Clutch Chart (TCC PCS) . When the ignition is ON, and the engine is OFF, there are no limits to this control. The solenoid valve remains ON until commanded OFF, and vice versa. When the output control is exited, the solenoid valve state is determined by the TCM. When the engine is running, control of Shift Solenoid Valve 1, 2, and 3 is not allowed.
Clear TAP (Transmission Adaptive Pressures)	Allows the TCM to reset the TAP cells to the original base value on individual shifts. There are no limits to using this output control. It may be performed with the engine running or when the ignition is ON, and the engine is OFF.
Transmission Adaptive Pressure Reset	Allows the TCM to reset the TAP cells to the original base value for all shifts. There are no limits to using this output control. It may be performed with the engine running or when the ignition is ON, and the engine is OFF.
Pressure Control Solenoid Valve 1 and 2	The TCM commands current to Pressure Control Solenoid Valve 1 and 2 in order to control clutch pressure. For Pressure Control Solenoid Valve 1, as the amperage increases, the clutch pressure decreases. As the amperage decreases, the clutch pressure increases. For Pressure Control Solenoid Valve 2, as the amperage increases, the clutch pressure increases. As the amperage decreases, the clutch pressure decreases. The amperage range is 0.00-1.00 A.
Shift Transmission Gear	The TCM commands upshifts and downshifts. The scan tool Commanded Gear parameter should correspond with the shift solenoid valve combination. Refer to Solenoid and Clutch Chart (PCS1, PCS2, SS1, SS2, and SS3)Solenoid and Clutch Chart (TCC PCS) . When the engine is running, the following control limits apply: The TCM does not allow a shift if it causes the engine RPM to exceed a calibrated limit. If a gear is requested and the engine speed is too high, the message "Engine speed too high" appears on the scan tool display. The TCM does not allow a downshift if the vehicle speed exceeds a calibrated limit. If a downshift is requested and the vehicle speed is too high, the message "Eng. is on and veh. speed too hi for downshift" appears on the scan tool display. The TCM does not allow an upshift that is greater than the current selected transmission range, PRNDL. For example, 3rd gear is not allowed if the transmission range is D2. If an upshift is requested that is greater than the current selected transmission range, the message "Eng. running and gear request is greater than the current TR" appears on the scan tool display.
TCC Pressure Control Solenoid Valve	The TCM commands the duty cycle of the TCC pressure control solenoid valve. The duty cycle is represented by a percentage of ON, energized, time. Approximately 90-100 percent duty cycle represents an ON, energized, commanded state. Zero percent represents an OFF, non-energized, commanded state. The scan tool TCC Duty Cycle parameter should match the commanded state. When the ignition is ON, and the engine is OFF, there are no limits to this control. The solenoid valve remains ON, 90-100 percent duty cycle, until commanded OFF, zero percent duty cycle, and vice versa. When the output control is exited, the solenoid valve duty cycle is determined by the TCM. When the engine is running, the following control limits apply: If the transmission range is Park, and the transmission is in hot mode, the TCC control solenoid valve may not be commanded OFF. If the solenoid valve is requested OFF, the message "TCC OFF command disabled in Hot Mode" appears on the scan tool display. The TCC control solenoid valve may not be commanded OFF for more than a calibrated amount of time. If the solenoid valve is commanded OFF, for a certain amount of time, the message "TCC OFF time has been exceeded" appears on the scan tool display.
Transmission Adaptive Values Learn	Transmission adaptive values learn is a procedure for which a series of test are run to allow the transmission control module (TCM) to learn individual clutch characteristics. Once the clutch data is learned, transmission adaptive values learn translates it to the adaptive data cells, which the TCM uses for clutch control during range shifts. Refer to FastLearn Procedure .
Preselect All TAP Cells (Transmission Adaptive Pressures)	Allows the TCM to reset, the TAP cells to the original base value on individual shifts. There are no limits to using this output control. It may be performed with the engine running or when the ignition is ON, and the engine is OFF.
Line Pressure Control Solenoid Valve	The TCM commands the Line Pressure Control Solenoid Valve ON and OFF. When the ignition is ON, and the engine is OFF, there are no limits to this control. The solenoid valve remains ON until commanded OFF, and vice versa. When the output control is exited, the solenoid valve state is determined by the TCM. When the engine is running, control of the line pressure control solenoid valve is not allowed.