For 1990-2009 cars

## Transmission Control Module Scan Tool Information 6T70

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 | 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.
1-2 Shift Time | -- | Seconds, Varies | 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 | -- | Seconds, Varies | 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 | -- | Seconds, Varies | 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 | -- | Seconds, Varies | 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 | -- | Seconds, Varies | 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 | 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%, where 0% represents an idle or coast request and 100% represents a request for wide open throttle (WOT).
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
Driver Shift Control | -- | 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 | 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 | -- | °C (°F), Varies | 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 | -- | RPM, Varies | This parameter displays the rotational speed of the engine expressed as revolutions per minute.
Engine Torque | -- | N·m, Varies | 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 15 lb ft of actual measured engine torque.
Gear Ratio | -- | Ratio, Varies | 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 | 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 | 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 | -- | Volts, 12-14 | This parameter displays the system voltage measured at the ignition feed.
IMS | -- | Park | 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 | -- | Varies | This parameter displays the status of the four A/B/C/P inputs from the automatic transmission internal mode switch. I 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 | This parameter displays OK, Out of Range.
Last Shift Time | -- | Seconds, Varies | This parameter displays the actual time of the last up shift. This value is only accurate if the shift was adaptable.
Line PC Sol. Pressure Command | -- | kPa (psi), Varies | This parameter displays kPa (psi).
PC Sol. 2 Pressure Command | -- | kPa (psi), Varies | This parameter displays kPa (psi).
PC Sol. 3 Pressure Command | -- | kPa (psi), Varies | This parameter displays kPa (psi).
PC Sol. 4 Pressure Command | -- | kPa (psi), Varies | This parameter displays kPa (psi).
PC Sol. 5 Pressure Command | -- | kPa (psi), Varies | This parameter displays kPa (psi).
Replicated OSS CKT Status | -- | OK | This parameter displays OK, Open/Short to GND, Short to Volts, or Indeterminate.
Shift Sol. 1 CKT Status | -- | OK | This parameter displays OK, Open/Short to GND, Short to Volts, or Indeterminate.
Shift Solenoid 1 | -- | On | 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 | This parameter displays OK, Open/Short to GND, Short to Volts, or Indeterminate.
Shift Solenoid 2 | -- | On | This parameter displays the commanded state of the 2-3, 3-4 shift solenoid valve (S2). The scan tool displays On/Off.
TCC Slip Speed | -- | RPM, Varies | 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 | -- | °C (°F) Varies | This parameter displays results in °C (°F)
TFP Switch 1 | -- | HI/LOW | This parameter displays the state of the first clutch oil pressure switch. The scan tool displays HI/LOW.
TFP Switch 3 | -- | HI/LOW | This parameter displays state of the 3rd clutch oil pressure switch. The scan tool displays HI/LOW.
TFP Switch 4 | -- | HI/LOW | This parameter displays state of the 4th clutch oil pressure switch. The scan tool displays HI/LOW.
TFP Switch 5 | -- | HI/LOW | This parameter displays state of the fifth clutch oil pressure switch. The scan tool displays HI/LOW.
Trans. Fluid Temp. | -- | °C (°F) Varies | 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 | -- | RPM, Varies | This parameter displays the rotational speed of the transmission input shaft. The scan tool displays input shaft speed is revolutions per minute (RPM).
Transmission OSS | -- | RPM, Varies | This parameter displays the rotational speed of the transmission output shaft expressed as revolutions per minute.

#### Scan Tool Output Controls

Output Control | Description
--- | ---
TCC Control Solenoid |

• | The transmission control module (TCM) commands the torque converter clutch pressure control (TCC PC) solenoid pressure in order to apply and release the TCC.

• | When the ignition is ON, and the engine is OFF, there are no limits to this control. The solenoid remains ON until commanded OFF and vice versa.

• | 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 PC 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 PC 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.

Shift Solenoid |

• | The TCM commands Shift Solenoid 1 and Shift Solenoid 2 ON and OFF.

• | When the ignition is ON, and the engine is OFF, there are no limits to this control. The solenoid remains ON until commanded OFF, and vice versa. When the output control is exited, the solenoid state is determined by the TCM.

• | When the engine is running, the following control limits apply:

- | The transmission range must be in Park or Neutral. If the transmission range is not Park or Neutral, the message "Engine running and transmission range is not Park/Neutral" appears on the scan tool display.

- | The solenoid remains ON until commanded OFF, and vice versa. When the output control is exited, the solenoid state is determined by the TCM.

- | 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.

Line PC Solenoid |

• | The scan tool is used to request pressure in increments of 200 kPa (30 psi) from 200-2200 kPa (30-320 psi). The TCM will then command the solenoid to achieve a pressure within a range based on the requested pressure. Refer to Solenoid Valve Pressure.

• | When the ignition is ON, and the engine is ON, the pressure request may be controlled within calibrated limits. There are no limits to the output control when the engine is OFF.

• | When the engine is running, the following control limits apply:

- | When the transmission range is Park or Neutral, the pressure request may be controlled within calibrated limits. The engine speed must be less than 1,500 RPM. If the engine speed is greater than 1,500 RPM, the message "TR in park/neutral and engine speed over 1,500 RPM" appears on the scan tool display.

- | When the transmission range is not Park or Neutral, the requested pressure can only be controlled equal to or greater than the pressure determined by the TCM. The TCM does not allow a pressure to be selected that may cause damage to the transmission. If the requested pressure is less than allowed by the TCM, the message "Requested pressure for the Line PC Solenoid is too low" 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.

Clutch PC Solenoids |

• | The TCM commands the pressure control solenoids in order to apply and release the clutches.

• | When the ignition is ON, and the engine is OFF, there are no limits to this control. The solenoid remains ON until commanded OFF, and vice versa. When the output control is exited, the solenoid state is determined by the TCM.

• | When the engine is running, the following control limits apply:

- | The transmission range must be in Park or Neutral. If the transmission range is not Park or Neutral, the message "Engine running and transmission range is not Park/Neutral" appears on the scan tool display.

- | The solenoid remains ON until commanded OFF, and vice versa. When the output control is exited, the solenoid state is determined by the TCM.

- | 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 Transmission |

• | The TCM commands upshifts and downshifts. The scan tool Commanded Gear parameter should correspond with the shift solenoid combination. Refer to the Shift Solenoid Valve State and Gear Ratio table.

• | 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 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 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.

- | 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.

High Side Driver 2 |

• | The TCM commands the driver for the solenoid voltage supply ON and OFF.

• | When the ignition is ON, and the engine is OFF, there are no limits to this control.

• | High side drivers may not be commanded ON and OFF with the scan tool if the engine is running.

Service Cleaning Procedure |

• | The scan tool is used to start and stop the transmission cleaning procedure algorithm.

• | The following control limits apply:

- | The engine must be running. The message "Engine not Running" will appear on the scan tool if this control is attempted without the engine running.

- | There cannot be active transmission DTCs. The message "Transmission Fault present" will appear on the scan tool if this control is attempted with transmission DTCs active.

- | The transmission range must be Park or Neutral. The message "Transmission not in PARK or NEUTRAL" will appear on the scan tool if this control is attempted with the transmission in any range other than Park or Neutral.

- | The vehicle speed cannot exceed 5 mph. The message "Vehicle Speed too high" will appear on the scan tool if this control is attempted with a vehicle speed greater than 8 km/h (5 mph).

- | The engine speed cannot exceed 2500 RPM. The message "Engine Speed too high" will appear on the scan tool if this control is attempted with an engine speed greater than 2500 RPM.

- | The transmission oil temperature must be at a normal operating temperature. The message "Transmission oil temperature out of range" will appear on the scan tool if this control is attempted without a transmission oil temperature between 70-110°C (158-230°F).

Service Fast Learn Adapts |

• | The scan tool is used to start and stop the transmission Fast Learn Adapt algorithm.

• | The following control limits apply:

- | The engine must be running. The message "Engine not Running" will appear on the scan tool if this control is attempted without the engine running.

- | There cannot be active transmission DTCs. The message "Transmission Fault present" will appear on the scan tool if this control is attempted with transmission DTCs active.