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 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.
Parameter | System State | Expected Value | Description |
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Operating Conditions: Engine at idle with the upper radiator hose hot and in closed loop operation, closed throttle, transmission in Park, accessories OFF, brake pedal not applied. | |||
1-2 Shift Time | Varies | Seconds | This parameter displays the actual time of the last adaptable 1-2 shift. The shift time is based on the gear ratio change after the commanded 1-2 shift. |
2-3 Shift Time | Varies | Seconds | This parameter displays the actual time of the last adaptable 2-3 shift. The shift time is based on the gear ratio change after the commanded 2-3 shift. |
3-4 Shift Time | Varies | Seconds | This parameter displays the actual time of the last adaptable 3-4 shift. The shift time is based on the gear ratio change after the commanded 3-4 shift. |
4-5 Shift Time | Varies | Seconds | This parameter displays the actual time of the last adaptable 4-5 shift. The actual shift time is obtained by measuring the time required for the input shaft to decelerate from the previous ratio to the current ratio. |
5-6 Shift Time | Varies | Seconds | This parameter displays the actual time of the last 5-6 shift. The shift time is base on the gear ratio change after the commanded 5-6 shift. |
Brake 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. |
Calc. Throttle Position | Varies | % | This parameter displays a calculated value, which is determined by the accelerator pedal position and the actual throttle position, used to optimize transmission controls. It represents the driver’s intended request for torque or acceleration. The range is 0-100 percent, where 0 percent represents an idle or coast request and 100 percent represents a request for wide open throttle (WOT). |
Commanded Gear | 1 | 1, 2, 3, 4 or 1, 2, 3, 4, 5 or Park/Neutral, Reverse, 1, 2, 3, 4, 5 | This parameter displays the current commanded state of the shift solenoid valves. The scan tool displays 1, 2, 3, 4 or 5 |
Driver Shift Control | Inactive | Active/Inactive | This parameter displays Active or Inactive. The scan tool displays Active when the gear selector is in the sport (S) position, which enables TAP shift. The scan tool displays Inactive when the gear selector is not in the S position, TAP shift disabled. |
Driver Shift Request | None | Upshift/ Downshift/ None/ Invalid | This parameter displays the current request from the TAP Shift System. This parameter will display up shift, downshift or invalid depending on the amount of voltage measured at the remote shift selector input and also will display none when there is no request. |
ECT | Varies | °C (°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 V). ECT is low at -40°C (-40°F) when the signal voltage is high (5 V). |
Engine Speed | Varies | RPM | This parameter displays the rotational speed of the engine expressed as revolutions per minute. |
Engine Torque | Varies | N·m (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 | Varies | Ratio | 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. |
High Side Driver 2 | Enabled | Enabled/Disabled | This parameter displays the High Side Driver 2 status on the scan tool. When the High Side Driver 2 is commanded OFF this displays Disabled, when the High Side Driver 2 is commanded ON this displays Enabled. |
High Side Driver 2 CKT Status | OK or Indeterminate | OK, Open/Short to Volts, Short to GND, Indeterminate | This parameter displays the High Side Driver 2 circuit status on the scan tool. If the voltage is low when the solenoid is commanded OFF, the scan tool will display Open/Short to GND. If the voltage is high when the solenoid is commanded ON, the scan tool will display Short to Volts. If no circuit fault is present the scan tool will display OK. |
Ignition Voltage | 12 to 14 volts | Volts | This parameter displays the system voltage measured at the ignition feed. |
IMS | Park | Park-Drive 1, Open, Invalid | This parameter displays PARK, PARK/REVERSE, REVERSE, REVERSE/NEUTRAL, NEUTRAL, NEUTRAL/DRIVE 4, DRIVE 4, DRIVE 4/DRIVE 3, DRIVE 3, DRIVE 3/DRIVE 2, DRIVE 2, DRIVE 2/DRIVE 1, DRIVE 1 or INVALID. The IMS Range display represents a decoded status of the four inputs from the IMS. The combination of IMS inputs are used to determine what position the manual valve is in at any time. |
IMS A/B/C/P | LOW/HI/HI/LOW | HI or LOW | This parameter displays the status of the four A/B/C/P inputs from the automatic transmission internal mode switch. HI indicates an ignition voltage signal and LOW indicates a 0 voltage signal. The scan tool will display HI/LOW, HI/LOW, HI/LOW, HI/LOW. |
ISS/OSS Supply Voltage | OK | OK, Out of Range | This parameter displays OK, Out of Range. |
Last Shift Time | Varies | Seconds | This parameter displays the actual time of the last up shift. This value is only accurate if the shift was adaptable. |
Line PC Sol. CKT Status | OK or Indeterminate | OK, Open/Short to GND, Short to Volts, Indeterminate | 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. |
PC Sol. 2 CKT Status | OK or Indeterminate | OK, Open/Short to GND, Short to Volts, Indeterminate | This parameter displays OK, Open/Short to GND, Short to Volts. |
PC Sol. 2 Pressure Comm | No | Yes/No | This parameter displays Yes or No. Yes, solenoid pressure is commanded. No, solenoid pressure is not commanded. |
PC Sol. 3 CKT Status | OK or Indeterminate | OK, Open/Short to GND, Short to Volts, Indeterminate | This parameter displays OK, Open/Short to GND, Short to Volts. |
PC Sol. 3 Pressure Comm | Yes | Yes/No | This parameter displays Yes or No. Yes, solenoid pressure is commanded. No, solenoid pressure is not commanded. |
PC Sol. 4 CKT Status | OK or Indeterminate | OK, Open/Short to GND, Short to Volts, Indeterminate | This parameter displays OK, Open/Short to GND, Short to Volts. |
PC Sol. 4 Pressure Comm | No | Yes/No | This parameter displays Yes or No. Yes, solenoid pressure is commanded. No, solenoid pressure is not commanded. |
PC Sol. 5 CKT Status | OK or Indeterminate | OK, Open/Short to GND, Short to Volts, Indeterminate | This parameter displays OK, Open/Short to GND, Short to Volts. |
PC Sol. 5 Pressure Comm | No | Yes/No | This parameter displays Yes or No. Yes, solenoid pressure is commanded. No, solenoid pressure is not commanded. |
Shift Sol. 1 CKT Status | OK or Indeterminate | OK, Open/Short to GND, Short to Volts, Indeterminate | This parameter displays OK, Open/Short to GND, Short to Volts, or Indeterminate. |
Shift Solenoid 1 | ON | On/Off | This parameter displays the commanded state of the reverse, 1st shift solenoid valve (S1). The scan tool displays On/Off. |
Shift Sol. 2 CKT Status | OK or Indeterminate | OK, Open/Short to GND, Short to Volts, Indeterminate | This parameter displays OK, Open/Short to GND, Short to Volts, or Indeterminate. |
Shift Solenoid 2 | ON | On/Off | This parameter displays the commanded state of the 2-3, 3-4 shift solenoid valve (S2). The scan tool displays On/Off. |
TCC PC Sol. Pressure Comm | No | Yes/No | This parameter displays Yes or No. Yes, solenoid pressure is commanded. No, solenoid pressure is not commanded. |
TCC Slip Speed | Varies | RPM | This parameter displays the difference between transmission input speed and engine speed. 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. |
TCM Temperature | Varies | °C (°F) | This parameter displays results in °C (°F). |
TFP Switch 1 | HI | HI/LOW | This parameter displays the state of the first clutch oil pressure switch. The scan tool displays HI/LOW. |
TFP Switch 3 | LOW | HI/LOW | This parameter displays state of the 3rd clutch oil pressure switch. The scan tool displays HI/LOW. |
TFP Switch 4 | LOW | HI/LOW | This parameter displays state of the 4th clutch oil pressure switch. The scan tool displays HI/LOW. |
TFP Switch 5 | LOW | HI/LOW | This parameter displays state of the fifth clutch oil pressure switch. The scan tool displays HI/LOW. |
Tow/Haul Mode (If equipped) | Inactive | Active/Inactive | This parameter displays ACTIVE when the transmission is operating in the tow/haul mode. In this mode the transmission control module (TCM) extends the length of time between upshifts and elevates transmission line pressure. Shift quality and TCC scheduling are also affected during tow/haul mode operation. The scan tool displays ACTIVE or INACTIVE. |
Trans. Fluid Temp. | Varies | °C (°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 V, and transmission fluid temperature is low -40°C (-40°F) when signal voltage is high, 5 V. |
Transmission ISS | Varies | RPM | This parameter displays the rotational speed of the transmission input shaft. The scan tool displays input shaft speed is revolutions per minute. |
Transmission OSS | 0 | RPM | This parameter displays the rotational speed of the transmission output shaft expressed as revolutions per minute. |
Output Control | Description | ||||||||||||||||
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High Side Driver 2 |
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Line PC Solenoid |
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PC Solenoid 2 Command |
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PC Solenoid 3 Command | |||||||||||||||||
PC Solenoid 4 Command | |||||||||||||||||
PC Solenoid 5 Command | |||||||||||||||||
Service Clean Procedure |
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Service Fast Learn Adapts |
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Shift Solenoid 1 |
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Shift Solenoid 2 | |||||||||||||||||
TCC PC Solenoid Command |
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