Transmission Control Module Scan Tool Information (8L45/90)
The Transmission Control Module Scan Tool Data List contains all transmission related parameters that are available on the scan tool. 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.
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 . If A DTC is set refer to Diagnostic Trouble Code (DTC) List - Vehicle .
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 with the upper radiator hose hot and in closed loop operation, closed throttle, transmission in park, accessories OFF, brake pedal not applied. | |||
| 9V Reference 1 Circuit Status | Varies | Not Run/OK/Malfunction | Indicates if the transmission control module has run a diagnostic circuit test and/or displays the present electrical condition of the circuit. |
| 9V Reference 2 Circuit Status | Varies | Not Run/OK/Malfunction | Indicates if the transmission control module has run a diagnostic circuit test and/or displays the present electrical condition of the circuit. |
| Calculated Line Pressure | Varies | kPa/PSI | Indicates a calculated line pressure value based on various engine and transmission input data. |
| Calculated Throttle Position | Varies | % | Indicates a calculated value based on accelerator pedal position and throttle position. Zero percent indicates idle position and 100 percent indicates wide open throttle. |
| Control Module Voltage | ON | ON/OFF | Indicates the transmission control module has received the control module voltage. |
| Driver Shift Control Mode | Varies | Inactive/Active | Indicates to the transmission control module the driver has taken control of transmission shifting by placing the gear shift lever in manual mode. Transmission control module will allow manual shifting within limits. |
| Driver Shift Request | Varies | Inactive/Upshift/ Downshift | Indicates to the transmission control module the driver has request an upshift or downshift. |
| Engine Coolant Temperature | Varies | °C (°F) | Indicates to the transmission control module the temperature of the engine coolant temperature, sent from the engine control module. |
| Engine Speed | Varies | RPM | Indicates the rotational speed of the engine crankshaft in revolutions per minute. |
| Engine Torque | Varies | N.m | Indicates a calculated value based on various engine input and output data values. |
| Gear Command | Varies | 1-8 | Indicates the current gear range the transmission control module has commanded. |
| Gear Ratio | Varies | GR10 1st = 4.696 2nd = 2.985 3rd = 2.156 4th = 1.779 5th = 1.526 6th = 1.278 7th = 1.000 8th = 0.854 9th = 0.689 10th = 0.636 Rev. = 4.911 |
Indicates a calculated value based on the RPM values of the ISS, Intermediate SS and OSS. |
| High Side Driver 1 or 2 Circuit High Voltage Test Status | Varies | Not Run/OK/Malfunction | Indicates if the transmission control module has run a diagnostic circuit test and/or displays the present electrical condition of the circuit. |
| High Side Driver 1 or 2 Circuit Low Voltage Test Status | Varies | Not Run/OK/Malfunction | Indicates if the transmission control module has run a diagnostic circuit test and/or displays the present electrical condition of the circuit. |
| High Side Driver 1 or 2 Circuit Open Test Status | Varies | Not Run/OK/Malfunction | Indicates if the transmission control module has run a diagnostic circuit test and/or displays the present electrical condition of the circuit. |
| High Side Driver 1 or 2 Command | Varies | Disabled/Enabled | Indicates the commanded state of the transmission control module high side drivers. |
| Ignition 1 Signal | ON | ON/OFF | Indicates the transmission control module has received the ignition 1 signal. |
| Ignition Accessory Signal | ON | ON/OFF | Indicates the transmission control module has received the ignition accessory voltage signal. |
| Ignition Voltage | Varies | Volts | Indicates the available ignition voltage to the transmission control module. |
| Internal Mode Switch A | Varies | Voltage | Indicates the voltage value on the hall effect switch A signal circuit to the transmission control module. |
| Internal Mode Switch A Status | Varies | Valid/Invalid | Indicates the voltage value on the hall effect switch A signal circuit to the transmission control module is valid or invalid. |
| Internal Mode Switch A/B/C/P/S | Varies | High/Low | Indicates the current state of each IMS hall effect switch when, the gear shift lever is in each gear range position. |
| Internal Mode Switch B | Varies | Voltage | Indicates the voltage value on the hall effect switch B signal circuit to the transmission control module. |
| Internal Mode Switch B Status | Varies | Valid/Invalid | Indicates the voltage value on the hall effect switch B signal circuit to the transmission control module is valid or invalid. |
| Internal Mode Switch C | Varies | Voltage | Indicates the voltage value on the hall effect switch C signal circuit to the transmission control module. |
| Internal Mode Switch C Status | Varies | Valid/Invalid | Indicates the voltage value on the hall effect switch C signal circuit to the transmission control module is valid or invalid. |
| Internal Mode Switch (IMS) | Varies | Park, Reverse, Neutral, Drive, Manual Mode | Indicates to the transmission control module the position of the gear shift lever. |
| Internal Mode Switch P | Varies | Voltage | Indicates the voltage value on the hall effect switch P signal circuit to the transmission control module. |
| Internal Mode Switch P Status | Varies | Valid/Invalid | Indicates the voltage value on the hall effect switch P signal circuit to the transmission control module is valid or invalid. |
| Internal Mode Switch S | Varies | Voltage | Indicates the voltage value on the hall effect switch S signal circuit to the transmission control module. |
| Internal Mode Switch S Status | Varies | Valid/Invalid | Indicates the voltage value on the hall effect switch S signal circuit to the transmission control module is valid or invalid. |
| ISS/OSS Supply Voltage | Varies | OK | Indicates the ISS/OSS voltage supply is in the specified range of 8.3-9.7 volts. |
| Power Mode | Varies | OFF/Accessory/Run | Indicates to the transmission control module the present position of the ignition switch. |
| TCC Slip Speed | Varies | RPM | Indicates the RPM difference between the torque converter impeller and the torque converter turbine when the converter clutch is applied. |
| Transmission Control Solenoid Valve 1-9 | Varies | OFF/ON | Indicates if the transmission control module has commanded a transmission control solenoid either ON or OFF. |
| Transmission Control Solenoid Valve 1-9 Control Circuit High Voltage Test Status | Varies | Not Run/OK/Malfunction | Indicates if the transmission control module has run a diagnostic circuit test and/or displays the present electrical condition of the circuit. |
| Transmission Control Solenoid Valve 1-9 Control Circuit Low Voltage Test Status | Varies | Not Run/OK/Malfunction | Indicates if the transmission control module has run a diagnostic circuit test and/or displays the present electrical condition of the circuit. |
| Transmission Control Solenoid Valve 1-9 Control Circuit Open Test Status | Varies | Not Run/OK/Malfunction | Indicates if the transmission control module has run a diagnostic circuit test and/or displays the present electrical condition of the circuit. |
| Transmission Control Solenoid Valve 1-9 Current | Varies | Amperage | Indicates the commanded amperage flowing through the solenoid at any given time. |
| Transmission Fluid Temperature | Varies | °C (°F) | Indicates the temperature of the transmission fluid in the transmission oil pan. |
| Transmission Hot Mode | NO | No/Yes | Indicates if the transmission control module has commanded hot mode operation. |
| Transmission Intermediate Speed Sensor | Varies | RPM | Indicates the rotational speed of the transmission carrier/output internal gear assembly in revolutions per minute. |
| Transmission ISS | Varies | RPM | Indicates the rotational speed of the transmission input shaft in revolutions per minute. |
| Transmission OSS | Varies | RPM | Indicates the rotational speed of the transmission output shaft in revolutions per minute. |
| Transmission Range | Varies | Park/Reverse/Neutral/Drive/Manual Mode | Indicates to the transmission control module the current gear position of the internal mode switch. |
| Up and Downshift Switch 2 | Varies | Inactive/Upshift/ Downshift/None | Indicates to the transmission control module the driver has request an upshift or downshift from the second additional set of switches, if equipped. |
Scan Tool Output Control Functions
| Parameter | System State | Expected Value | Description |
|---|---|---|---|
| Configure/Reset Function | - | - | A service fast learn procedure to be perform for any internal component repair/replacement, solenoid/valve body replacement, complete transmission replacement or transmission control module replacement. |
| High Side Driver 1 Command | Varies | Disabled/Enable | Allows you to command the high side driver 1 ON or OFF. |
| High Side Driver 2 Command | Varies | Disabled/Enable | Allows you to command the high side driver 2 ON or OFF. |
| Shift Transmission Gear | Varies | 1-8 | Allows you to upshift the transmission from 1st gear to 8th gear and downshift from 8th to 1st gear. Be aware the transmission control module has limits to the gear selection, protect the engine and transmission. |
| Transmission Control Solenoid Valve 1-7 | Varies | 0-1.2 Amps | Allow you to command the transmission solenoids 1-7 electrical current from 0-1.2 amps. |
| Transmission Control Solenoid Valve 8 and 9 | Varies | OFF/ON | Allows you to command solenoid valve 8 and 9 OFF or ON. |