Scan Tool Testing and Procedures

Output State Control (OSC) Mode





Output state control (OSC) using the VCM/IDS scan tool allows the technician to easily and quickly control the main functions and components of this transmission. OSC is used to help test the electrical, hydraulic or mechanical concerns related to the transmission. The VCM/IDS also provides PID information, along with the OSC functions, to accurately diagnose the transmission. For example, OSC allows the technician to shift the transmission, or engage the converter clutch, or command line pressure or turn a solenoid OFF and ON.

Output State Control (OSC) Procedures
Retrieve the continuous codes, carry out a key ON engine OFF (KOEO) and key ON engine running (KOER) on-demand self test before using OSC. Any DTCs related to the transmission range (TR) sensor or the output shaft speed (OSS) sensor must be fixed or the PCM will not allow OSC to operate.

Using the scan tool, OSC has 2 menus for operation, the Bench Mode and the Drive Mode.

OSC - Bench Mode
The Bench Mode is functional only when the vehicle range selector is in PARK or NEUTRAL. The Bench Mode may be used when the engine is either ON (running) or OFF (not running). The Bench Mode allows the technician to function the following components:
^ SSA - Directs PCM to command Shift Solenoid 1 OFF or ON
^ SSB - Directs PCM to command Shift Solenoid 2 OFF or ON
^ TCC - Directs PCM to command the Torque Converter Solenoid from 0% duty cycle to 100% duty cycle
^ LINEDSD - Directs PCM to command line pressure from 234 kPa to 1.5 MPa (34 psi to 217 psi). The PCM will command the appropriate electronic pressure control (EPC) current to obtain the commanded line pressure.

SSA, SSB and TCC in Bench Mode
These OSC functions are used to command SSA, SSB and TCC solenoids OFF and ON when carrying out an electrical circuit check.

The OSC functions for parameters SSA, SSB and TCC allow the technician to choose the following options:
^ OFF - Directs PCM to command the solenoid OFF
^ ON - Directs PCM to command the solenoid ON

The requirements for SENDING an OSC command for SSA, SSB or TCC are as follows:
^ Key on and engine not running or key on and engine running at idle
^ Gear selector in PARK or NEUTRAL

The vehicle requirements must be met when sending the OSC command for SSA, SSB and TCC solenoids. If the vehicle requirements are not met when sending the OSC command, the command will be cancelled. If after sending the OSC command the vehicle requirements are no longer met, the OSC command will be cancelled.

LINEDSD in Bench Mode
The LINEDSD in Bench Mode may be used when carrying out an electrical check on the EPC solenoid or to test the functionality of the transmission's electronic control of the line pressure. When testing the EPC for controlling the line pressure, the technician is required to run the engine greater than 1,500 rpm. The installation of a hydraulic pressure gauge is required to actually test whether the transmission line pressure is correct. This will test whether the hydraulic pump, the pressure regulator and the EPC solenoid and other associated mechanical and hydraulic components are working correctly.

When carrying out an electrical test on the EPC solenoid, set LINEDSD to 1,379 kPa (200 psi) to command the EPC solenoid OFF and 345 kPa (50 psi) to command the EPC solenoid ON. Commanding 1,379 kPa (200 psi) may not electrically turn the pressure solenoid completely off and commanding 345 kPa (50 psi) may not electrically turn the pressure solenoid completely on.

The vehicle requirements for sending an OSC command for LINEDSD in Bench Mode are as follows:
^ KOER (engine speed greater than 1,500 rpm)
^ Range selector in PARK or NEUTRAL

The vehicle requirements must be met when sending the OSC command for EPC. If the vehicle requirements are not met when sending the OSC command, the command will be cancelled. If after sending the OSC command the vehicle requirements are no longer met, the OSC command will be cancelled.

OSC - Drive Mode
The Drive Mode allows control of 2 transmission functions. Each OSC function has a unique set of vehicle operating requirements that the technician is required to meet before being allowed to operate OSC. The recommended procedure, when using the Drive Mode, is to command one parameter at a time. The Drive Mode allows the technician to control the following OSC functions on the transmission:
^ GEAR - Directs the PCM to up-shift or down-shift
^ TCC - Directs the PCM to lock or unlock the torque converter clutch

GEAR in Drive Mode
The OSC function is used to test the transmission gear changes. The advantage of using OSC for changing gears is to allow the technician to easily test a specific gear and/or upshift or downshift that has been identified as the customer complaint. When using OSC to command a shift change, the PCM should command the correct or normal pressure for that shift. The transmission will remain in the gear that OSC has commanded until OSC commands another gear or OSC is cancelled.

The OSC functions for the OSCGEAR parameter allow the technician to choose the following options:
^ 1 - Directs PCM to command 1st gear
^ 2 - Directs PCM to command 2nd gear
^ 3 - Directs PCM to command 3rd gear
^ 4 - Directs PCM to command 4th gear

The vehicle requirements must be met when sending the OSC command for GEAR. If the vehicle requirements are not met when sending the OSC command, the command will be cancelled. If after sending the OSC command the vehicle requirements are no longer met, the OSC command will be cancelled.

It is recommended to use the TCC parameter in OSC to first turn OFF the converter clutch when testing the transmission gear changes. This will allow the technician to evaluate just the gear changes. If the torque converter clutch is not turned off, then the PCM may command the torque converter clutch to lock during a shift. This could make it more difficult for the technician to determine whether a bad shift is the result of the torque converter engaging or the actual gear change.

The vehicle requirements for sending a GEAR value is as follows:
^ Engine is running
^ Gear selector is in OVERDRIVE
^ Vehicle speed is greater than 3 km/h (2 mph)
^ Vehicle speed must be lower than 48 km/h (30 mph) to command a downshift to 1st gear
^ Vehicle speed must be lower than 97 km/h (60 mph) to command a downshift to 2nd gear
^ Vehicle speed must be lower than 145 km/h (90 mph) to command a downshift to 3rd gear
^ Vehicle speed must be greater than 48 km/h (30 mph) to command an upshift to 4th gear

TCC in Drive Mode
The OSC function is used to test whether the torque converter clutch (TCC) is locking and unlocking correctly.

The OSC functions for the TCC parameter allow the technician to do the following:
^ Command TCC solenoid ON (100% duty cycle) to lock the TCC
^ Command TCC solenoid OFF (0% duty cycle) to unlock the TCC

The vehicle requirements must be met when sending the OSC command for TCC. If the vehicle requirements are not met when sending the OSC command, the command will be cancelled. If after sending the OSC command the vehicle requirements are no longer met, the OSC command will be cancelled.

The vehicle requirements for sending the OSC command for TCC are as follows:
^ Engine is running
^ Gear selector is in OVERDRIVE
^ Vehicle speed is greater than 3 km/h (2 mph)
^ Transmission fluid temperature (TFT) is between 16-116° C (60-240° F)
^ Brake is off when vehicle speed is below 32 km/h (20 mph)
^ Not an excessive load on the engine
^ Not during an upshift or downshift
^ Engine speed is greater than 1,500 rpm

Using Output State Control (OSC) and Monitoring PIDs
To confirm that the OSC command was sent by the scan tool and the PCM has accepted the OSC command, a corresponding PID for each OSC parameter must be monitored. After sending the OSC command, the corresponding PID value should be the same as the OSC command. Additional PIDs should be monitored to help the technician accurately diagnose the transmission.

The following is a list of PIDs to monitor while using OSC.