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Transmission Control Module Scan Tool Information AF33-5

Table 1: Scan Tool Data Parameters
Table 2: Scan Tool Output Controls

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.

Important: 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 parts.

Only the parameters listed below are used/referenced in this manual 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 range 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

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.

TP Angle

0 percent

This parameter displays a percentage that is calculated based on TP sensor voltage. The TP angle should display 0 percent at idle and 100 percent at wide open throttle (WOT).

Battery Voltage

12.8 volts

This parameter displays the Battery Positive Voltage measured at the TCM BATT fuse.

Brake Switch

Released

This parameter displays the state of the brake switch circuit input. The scan tool will display Applied when the brake pedal is depressed and Released when the brake pedal is released.

Commanded Gear

1

This parameter displays the current commanded state of the shift solenoid valves. The scan tool displays 1, 2, 3, 4 or 5.

Cruise

Disabled

This parameter displays the commanded state of the cruise control system. The scan tool displays ENABLED or DISABLED. When the display indicates ENABLED, the PCM is allowing cruise control operation. When the display indicates DISABLED, the PCM has disabled cruise control operation. When the cruise control display is ENABLED, shift patterns will be altered for 2-3 and 3-4 upshifts or 4-3 and 3-2 downshifts.

ECT

85-105°C (185-220°F)

This parameter displays the input signal from the engine coolant temperature (ECT) sensor. ECT is high at 151°C (304°F) when the signal voltage is low, 0 volt. ECT is low at -40°C (-40°F) when the signal voltage is high, 5 volt.

Engine Speed

660-680 RPM

This parameter displays the rotational speed of the engine expressed as revolutions per minute.

Engine Torque

0 N·m (0 lb ft)

This parameter displays a calculated value based on engine load, throttle position, mass air flow, and other engine inputs. This parameter is accurate to within 20 N·m (15 lb ft) of actual measured engine torque.

Gear Ratio

7.97:1

This parameter displays the actual transmission gear ratio. The scan tool displays the gear ratio calculated from the automatic transmission input shaft speed sensor (AT ISS) and the automatic transmission output shaft speed sensor (AT OSS) inputs.

Ignition Voltage

12.6-14.0 volts

This parameter displays the system voltage measured at the ignition feed.

Last 1-2 Shift Status

Inconclusive, Good

This parameter displays the shift quality of the last 1-2 gearshift. The scan tool displays Good, Long, Short, Tie-Up, Flare, or Inconclusive. Inconclusive is displayed if the conditions for determining the last shift status were not met.

Last 2-1 Shift Status

Inconclusive, Good

This parameter displays the shift quality of the last 2-1 gearshift. The scan tool displays Good, Long, Short, Tie-Up, Flare, or Inconclusive. Inconclusive is displayed if the conditions for determining the last shift status were not met.

Last 2-3 Shift Status

Inconclusive, Good

This parameter displays the shift quality of the last 2-3 gearshift. The scan tool displays Good, Long, Short, Tie-Up, Flare, or Inconclusive. Inconclusive is displayed if the conditions for determining the last shift status were not met.

Last 2-4 Shift Status

Inconclusive, Good

This parameter displays the shift quality of the last 2-4 gearshift. The scan tool displays Good, Long, Short, Tie-Up, Flare, or Inconclusive. Inconclusive is displayed if the conditions for determining the last shift status were not met.

Last 3-2 Shift Status

Inconclusive, Good

This parameter displays the shift quality of the last 3-2 gearshift. The scan tool displays Good, Long, Short, Tie-Up, Flare, or Inconclusive. Inconclusive is displayed if the conditions for determining the last shift status were not met.

Last 3-4 Shift Status

Inconclusive, Good

This parameter displays the shift quality of the last 3-4 gearshift. The scan tool displays Good, Long, Short, Tie-Up, Flare, or Inconclusive. Inconclusive is displayed if the conditions for determining the last shift status were not met.

Last 4-2 Shift Status

Inconclusive, Good

This parameter displays the shift quality of the last 4-2 gearshift. The scan tool displays Good, Long, Short, Tie-Up, Flare, or Inconclusive. Inconclusive is displayed if the conditions for determining the last shift status were not met.

Last 4-3 Shift Status

Inconclusive, Good

This parameter displays the shift quality of the last 4-3 gearshift. The scan tool displays Good, Long, Short, Tie-Up, Flare, or Inconclusive. Inconclusive is displayed if the conditions for determining the last shift status were not met.

Last 4-5 Shift Status

Inconclusive, Good

This parameter displays the shift quality of the last 4-5 gearshift. The scan tool displays Good, Long, Short, Tie-Up, Flare, or Inconclusive. Inconclusive is displayed if the conditions for determining the last shift status were not met.

Last 5-4 Shift Status

Inconclusive, Good

This parameter displays the shift quality of the last 5-4 gearshift. The scan tool displays Good, Long, Short, Tie-Up, Flare, or Inconclusive. Inconclusive is displayed if the conditions for determining the last shift status were not met.

Line PC Sol. Actual Current

0.96 amps

This parameter displays the actual current flow of the line pressure control (PC) solenoid valve circuit. The scan tool displays current flow in amps. A reading of 0.00 amps, no current is flowing, indicates high line pressure. A reading of 1.10 amps, a high flow of current, indicates low line pressure.

Line PC Sol. CKT Status

OK

This parameter displays whether an open, short to voltage or ground exists in the line pressure control (PC) solenoid valve feedback signal circuit. The scan tool displays OK, Open/Short to Volts, Short to GND, or Indeterminate.

Line PC Sol. Duty Cycle

59 percent

This parameter displays the commanded state of the line pressure control (PC) solenoid valve. The scan tool displays the percentage of the PC solenoid valve energized On time. A reading of 0 percent indicates zero On time, or a non-energized, commanded Off, state. A reading of 100 percent represents a fully energized, commanded On, state.

Line PC Sol. Ref. Current

1.0 amps

This parameter displays the commanded reference current flow of the line pressure control (PC) solenoid valve circuit. The scan tool displays current flow in amps. A reading of 0.00 amps, no current is flowing, indicates high line pressure. A reading of 1.10 amps, a high flow of current, indicates low line pressure.

Shift PC Sol. Actual Current

0.66 amps

This parameter displays the actual current flow of the shift pressure control (PC) solenoid valve circuit. The scan tool displays current flow in amps. A reading of 0.00 amps, no current is flowing, indicates an actual high shift pressure. A reading of 1.10 amps, a high flow of current, indicates low shift pressure.

Shift PC Sol. CKT Status

OK

This parameter displays whether an open, short to voltage or ground exists in the shift pressure control (PC) solenoid valve feedback signal circuit. The scan tool displays OK, Open/Short to Volts, Short to GND.

Shift PC Sol. Duty Cycle

39 percent

This parameter displays the commanded state of the shift pressure control (PC) solenoid valve. The scan tool displays the percentage of the shift PC solenoid valve energized ON time. A reading of 0 percent indicates zero ON time, a non-energized commanded OFF state. A reading of 100 percent represents an energized commanded ON state.

Shift PC Sol. Ref. Current

0.66 amps

This parameter displays the commanded reference current flow of the shift pressure control (PC) solenoid valve circuit. The scan tool displays current flow in amps. A reading of 0.00 amps, no current is flowing, indicates an actual high shift pressure. A reading of 1.10 amps, a high flow of current, indicates low shift pressure.

Shift Solenoid 1

Off

This parameter displays the commaded state of the reverse, 1st shift solenoid valve (S1). The scan tool displays On/Off.

Shift Solenoid 1 CKT Status

OK

This parameter displays whether an open, short to voltage or ground exists in the shift solenoid valve 1 feedback signal circuit. The scan tool displays OK, Open/Short to Volts, Short to GND.

Shift Solenoid 2

Off

This parameter displays the commanded state of the 2-3, 3-4 shift solenoid valve (S2). The scan tool displays On/Off.

Shift Solenoid 2 CKT Status

OK

This parameter displays whether an open or short to voltage or ground exists in the 2-3, 3-4 shift solenoid valve (S2) feedback signal circuit. The scan tool displays OK, Open/Short to Volts, or Short to GND.

Shift Solenoid 3

Off

This parameter displays the commanded state of the 1-2, 2-3, reverse shift solenoid valve (S3). The scan tool displays On/Off.

Shift Solenoid 3 CKT Status

OK

This parameter displays whether an open or short to voltage or ground exists in the 1-2, 2-3, reverse, shift solenoid valve (S3) feedback signal. The scan tool displays OK, Open/Short to Volts, or Short to GND.

Shift Solenoid 4

Off

This parameter displays commanded state of the 3-4, 4-5 shift solenoid valve (S4). The scan tool displays On/Off.

Shift Solenoid 4 CKT Status

OK

This parameter displays whether an open or short to voltage or ground exists in the 3-4, 4-5 shift solenoid valve (S4) feedback signal circuit. The scan tool displays OK, Open/Short to Volts, or Short to GND.

Shift Solenoid 5

Off

This parameter displays the commanded state of the reverse shift solenoid valve (S5). The scan tool displays On/Off.

Shift Solenoid 5 CKT Status

OK

This parameter displays whether an open or short to voltage or ground exists in the reverse shift solenoid valve (S5) feedback signal circuit. The scan tool displays OK, Open/Short to Volts, or Short to GND.

TCC PC Sol. Actual Current

0.20 amps

This parameter displays the actual current of the torque converter clutch (TCC) lock up pressure control (PC) solenoid valve circuit. The scan tool displays current flow in amps. A reading of 0.00 amps, no current flowing, indicates a low TCC apply pressure. A reading of 1.10 amps, a high flow of current, indicates a high TCC apply pressure.

TCC PC Sol. CKT Status

OK

This parameter displays whether an open or short to voltage or ground exists in the torque converter clutch (TCC) pressure control (PC) solenoid valve feedback signal circuit. The scan tool displays OK, Open/Short to Volts, Short to GND, or Indeterminate.

TCC PC Sol. Duty Cycle

14 percent

This parameter displays the commanded On time of the torque converter clutch (TCC) solenoid valve. The scan tool displays On time in percentage. A reading of 100 percent represents an energized, commanded On state. A reading of 0 percent represents a non-energized commanded OFF state.

TCC PC Sol. Ref. Current

0.20 amps

This parameter displays the commanded reference current flow of the torque converter clutch (TCC) lock up pressure control (PC) solenoid valve circuit. The scan tool displays current flow in amps. A reading of 0.00 amps, no current flow, indicates an actual high commanded apply pressure. A reading of 1.10 amps, a high flow of current, indicates a high commanded TCC apply pressure.

TCC Slip Speed

0-20 RPM

This parameter displays 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 valve indicates the engine speed is greater than the input speed acceleration. A value of zero indicates the engine speed is equal to the input speed, TCC applied.

TR SW.

Park

This parameter displays the decoded status of the four A/B/C/P inputs from the transmission range switch. The scan tool displays Park, Reverse, Neutral, Drive, Intermediate, Low, and invalid. If a valid combination of inputs is not detected, invalid will be displayed.

Trans Fluid Temp.

158°C (316°F)

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 volt. Transmission fluid temperature is low, -40°C (-40°F), when signal voltage is high, 5 volt.

Trans. Protection Mode

Off

This parameter displays the status of the transmission protection mode. The scan tool displays Yes/No. Yes indicates that a fault has occurred, and that the transmission protection mode is active and has inhibited certain gears, as well as taken other actions to prevent damage.

Transmission Hot Mode

Off

This parameter displays the automatic transmission fluid temperature (TFT) and displays On or Off. Off indicates that the TFT has not exceeded 130°C (266°F). On indicates that the TFT has exceeded 130°C (266°F) and has not cooled to 120°C (248°F) for greater that 5 seconds. These numbers are approximate and differ with transmissions.

Transmission ISS

700-800 RPM

This parameter displays the rotational speed of the transmission input shaft. The scan tool displays input shaft speed as revolutions per minute (RPM).

Transmission OSS

0 RPM

This parameter displays the rotational speed of the transmission output shaft. The scan tool displays output shaft speed as revolutions per minute (RPM). On four-wheel drive applications, the transfer case output shaft speed is measured.

Vehicle Speed

0 Km/h (0 mph)

This parameter displays the speed at which the vehicle is traveling. The scan tool displays vehicle speed as kilometers per hour (km/h), miles per hour (MPH). The vehicle speed is calculated based on the input signal from the automatic transmission output shaft speed sensor.

Scan Tool Output Controls

Output Control

Description

Line PC Sol. Electrical
    • The TCM commands the amperage, current, to the line pressure control solenoid in order to control transmission line pressure. As the amperage increases, the line pressure decreases. As the amperage decreases, the line pressure increases. The amperage range is 0.20-1.10 and may be commanded in one-tenth amp increments. If an amperage below 0.20 amp is commanded, the message "Requested override current out of range" appears on the scan tool display.
    • The Line PC Sol. Electrical output control can be performed when the ignition is ON, and the engine is OFF. The reference, commanded, amperage may be controlled within calibrated limits. The scan tool parameter "Line PC Sol. Ref. Current" changes, but the parameter "Line PC Sol. Actual Current" does not change. The reference current remains until commanded otherwise. If output control is attempted while the engine is running, the message "Output control not allowed while engine is running" appears on the scan tool display.

Line PC Sol. Functional
    • The TCM commands the amperage, current, to the line pressure control solenoid in order to control transmission line pressure. As the amperage increases, the line pressure decreases. As the amperage decreases, the line pressure increases. The amperage range is 0.00-1.10 and may be commanded in one-tenth amp increments.
    • The Line PC Sol. Functional output control can be performed when the engine is running. The following control limits apply:
       - When the transmission range is Park or Neutral, the reference, commanded, amperage may be controlled within calibrated limits. Both the scan tool parameters "Line PC Sol. Ref. Current" and "Line PC Sol. Actual Current" change. Both current readings remain until commanded otherwise.
       - When the transmission range is not Park or Neutral, the message "Transmission NOT is Park or Neutral" appears on the scan tool display.
       - Transmission range DTCs must not be active. If a transmission range DTC is active, the message "Engine running with transmission DTC present" appears on the scan tool display.

TCC PC Sol. Electrical
    • The TCM commands the duty cycle of the TCC pressure control solenoid. 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 PC Sol. Duty Cycle parameter should match the commanded state.
    • The TCC PC Sol. Electrical output control can be performed when the ignition is ON, and the engine is OFF. There are no limits to this control. The solenoid 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 duty cycle is determined by the TCM. If output control is attempted while the engine is running, the message "Output control not allowed while engine is running" appears on the scan tool display.

TCC PC Sol. Functional
    • The TCM commands the duty cycle of the TCC pressure control solenoid. 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 PC Sol. Duty Cycle parameter should match the commanded state.
    • The TCC PC Sol. Funtional output control can be performed when the engine is running. The following control limits apply:
       - If the transmission range is 3rd, 4th, or 5th, and the transmission is in hot mode, the TCC control solenoid may not be commanded OFF. If the solenoid is requested OFF, the message "TCC OFF command disabled in Hot Mode" appears on the scan tool display.
       - The TCC control solenoid may not be commanded OFF for more than a calibrated amount of time. If the solenoid is commanded OFF, for a certain amount of time, the message "TCC OFF time has been exceeded" appears on the scan tool display.
       - The TCC control solenoid may not be commanded ON if the vehicle speed is below a calibrated limit. If the solenoid is commanded ON below the calibrated limit the message "Vehicle speed too low" appears on the scan tool display.

Shift PC Sol. Electrical
    • The TCM commands the amperage, current, to the shift pressure control solenoid in order to control transmission line pressure. As the amperage increases, the line pressure decreases. As the amperage decreases, the line pressure increases. The amperage range is 0.20-1.10 and may be commanded in one-tenth amp increments.
    • When the ignition is ON, and the engine is OFF, the reference, commanded, amperage may be controlled within calibrated limits. The scan tool parameter "Shift PC Sol. Ref. Current" changes, but the parameter "Shift PC Sol. Actual Current" does not change. The reference current remains until commanded otherwise.
    • When the engine is running, the following control limits apply:
       - If output control is attempted while the engine is running, the message "Output control not allowed while engine is running" appears on the scan tool display.
       - Transmission range DTCs must not be active. If a transmission range DTC is active, the message "Engine running with transmission DTC present" appears on the scan tool display.

Shift Solenoid 1
    • The TCM commands the reverse, 1st shift solenoid valve (S1) ON and OFF. The scan tool Shift Solenoid 1 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 remains OFF until commanded ON, and vice versa. When the output control is exited, the solenoid state is determined by the TCM.
    • This output control is not allowed when the engine is running. If the engine is running, the output control will abort, and the message "Output Control not allowed while Engine is Running" appears on the scan tool.

Shift Solenoid 2
    • The TCM commands the 2-3, 3-4 shift solenoid valve (S2) ON and OFF. The scan tool Shift Solenoid 2 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 remains OFF until commanded ON, and vice versa. When the output control is exited, the solenoid state is determined by the TCM.
    • This output control is not allowed when the engine is running. If the engine is running, the output control will abort, and the message "Output Control not allowed while Engine is Running" appears on the scan tool.

Shift Solenoid 3
    • The TCM commands the 1-2, 2-3 shift solenoid valve (S3) ON and OFF. The scan tool Shift Solenoid 3 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 remains OFF until commanded ON, and vice versa. When the output control is exited, the solenoid state is determined by the TCM.
    • This output control is not allowed when the engine is running. If the engine is running, the output control will abort, and the message "Output Control not allowed while Engine is Running" appears on the scan tool.

Shift Solenoid 4
    • The TCM commands the 3-4, 4-5 shift solenoid valve (S4) ON and OFF. The scan tool Shift Solenoid 4 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 remains OFF until commanded ON, and vice versa. When the output control is exited, the solenoid state is determined by the TCM.
    • This output control is not allowed when the engine is running. If the engine is running, the output control will abort, and the message "Output Control not allowed while Engine is Running" appears on the scan tool.

Shift Solenoid 5
    • The TCM commands the reverse shift solenoid valve (S5) ON and OFF. The scan tool Shift Solenoid 5 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 remains OFF until commanded ON, and vice versa. When the output control is exited, the solenoid state is determined by the TCM.
    • This output control is not allowed when the engine is running. If the engine is running, the output control will abort, and the message "Output Control not allowed while Engine is Running" appears on the scan tool.

Shift Trans.
    • The TCM commands upshifts and downshifts. The scan tool Commanded Gear parameter should match the commanded state.
    • When the ignition is ON, and the engine is OFF, there are no limits to this control. The scan tool shift solenoid states change to match the Commanded Gear selected.
    • When the engine is running, the following control limits apply:
       - The TCM does not allow a shift if it will cause 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 3-2 or 2-1 downshift if the vehicle speed exceeds a calibrated limit. If either downshift is requested and the vehicle speed is too high, the message "Eng. is on and veh. speed too hi for 3-2 or 2-1 downshift" appears on the scan tool display.
       - The TCM does not allow a 4-3 downshift if the vehicle speed exceeds a calibrated limit. If a 4-3 downshift is requested and the vehicle speed is too high, the message "Vehicle speed too high" appears on the scan tool display.
       - The TCM does not allow an upshift if the vehicle speed exceeds a calibrated limit. If an upshift is requested and the vehicle speed is too high, the message "Vehicle speed too high" appears on the scan tool display.

Trans. Adaptives Reset
    • The TCM clears, or resets, all TAP cells to zero.
    • There are no limits to using this control. It may be performed with the engine running or when the ignition is ON, and the engine is OFF.

Trans. Oil Life Reset
    • The TCM resets the amount of transmission oil life remaining to a value selected.
    • There are no limits to using this control. It may be performed with the engine running or when the ignition is ON, and the engine is OFF.