Scan Tool Testing and Procedures
Output State Control (OSC) ModeDescription
Output state control (OSC) on the NGS or WDS diagnostic tool allows the technician to easily and quickly control the main functions and components of the 4F50N transmission. OSC is used to help test the electrical, hydraulic or mechanical concerns related to the transmission. The NGS or WDS also provides PID information, along with the OSC functions, to accurately diagnose the transmission. For example, OSC allows the technician to shift the transmission, engage the converter clutch, command line pressure or turn a solenoid off and on.
Procedure
NOTE: Retrieve Continuous Codes and carry out a KOEO and KOER On - Demand Self Test before using any OSC. Any Diagnostic Trouble Codes (DTCs) related to the Transmission Range Sensor (TRS) or the Output Shaft Speed (OSS) Sensor or the Vehicle Speed Sensor (VSS) must be fixed or the PCM will not allow the OSC to operate.
For the NGS, OSC has two menus for operation, the BENCH MODE and the DRIVE MODE.
OSC - BENCH MODE
The BENCH MODE is functional ONLY when the vehicle gear 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:
^ SS1 - Directs PCM to command Shift Solenoid 1 OFF or ON
^ SS2 - Directs PCM to command Shift Solenoid 2 OFF or ON
^ SS3 - Directs PCM to command Shift Solenoid 43 OFF or ON
^ TCC - Directs PCM to command the Torque Converter Solenoid OFF or ON (OFF = 0% duty cycle and ON = 100% duty cycle)
^ LINEPDSD - Directs PCM to command line pressure to either 75, 100, 125, 150, 175, 200, 225 or 250 PSI. The PCM will command the appropriate EPC current to obtain the commanded line pressure.
SS1, SS2, SS3 and TCC in BENCH MODE
These OSC functions are used to command SST, SS2, SS3 and TCC solenoids OFF and ON when carrying out an electrical circuit check.
The OSC functions for parameters SST, SS2, SS3 and TCC allows the technician to choose the following options:
^ OFF - Directs the PCM to command the solenoid OFF
^ ON - Directs the PCM to command the solenoid ON
^ XXX - Cancels OSC command for that particular solenoid and returns to normal operation.
The vehicle requirements for SENDING an OSC value for SST, SS2, SS3 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 value for SST, SS2, SS3 or TCC solenoids. If the vehicle requirements are NOT MET when SENDING the OSC value, an ERROR MESSAGE will appear. When the ERROR MESSAGE is received, OSC is aborted and must be restarted. After SENDING the OSC value, if the vehicle requirements are no longer met, the ERROR MESSAGE will NOT appear, but the PCM will cancel the OSC value and NO ERROR message will appear. The OSC value XXX may be sent anytime to cancel OSC.
LINEPDSD in BENCH MODE
The LINEPDSD in BENCH MODE may be used when carrying out an electrical check on the EPC solenoid or used to test the functionality of the transmissions electronic control of the line pressure. When testing the EPC for controlling the line pressure, the technician is required to run the engine higher than 1500 RPM. The hook - up of a hydraulic pressure gauge is required to actually test whether the transmission line pressure is correct. This will test 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 LINEPDSD to 250 PSI to command the EPC solenoid OFF and 75 PSI to command the EPC solenoid ON. Commanding 250 PSI may not turn the pressure solenoid fully ON and commanding 75 PSI may not command the EPC fully OFF.
The OSC functions for the parameter LINEPDSD allows the technician to choose the following options:
^ 75 - Directs the PCM to command the line pressure to 60 PSI
^ 100 - Directs the PCM to command the line pressure to 90 PSI
^ 125 - Directs the PCM to command the line pressure to 120 PSI
^ 150 - Directs the PCM to command the line pressure to 150 PSI
^ 175 - Directs the PCM to command the line pressure to 180 PSI
^ 200 - Directs the PCM to command the line pressure to 210 PSI
^ 225 - Directs the PCM to command the line pressure to 240 PSI
^ 250 - Directs the PCM to command the line pressure to 270 PSI
^ XXX - Cancels the OSC command for line pressure and returns to normal operation
The vehicle requirements for SENDING an OSC value for LINEPDSD in BENCH MODE is as follows:
^ Key ON and engine OFF or key ON and engine RUNNING higher than 1500 RPM
^ Gear selector in PARK or NEUTRAL
The vehicle requirements MUST BE MET when SENDING the OSC value for EPC. If the vehicle requirements are NOT MET when SENDING the OSC value, an ERROR MESSAGE will appear. When the ERROR MESSAGE is received, OSC is aborted and must be restarted. After SENDING the OSC value, if the vehicle requirements are no longer met, the ERROR MESSAGE will NOT appear, but the PCM will cancel the OSC value. The OSC value XXX may be sent anytime to cancel OSC.
OSC - DRIVE MODE
The DRIVE MODE allows the control of two transmission functions. Each OSC function has a unique set of vehicle operating requirements that the technician is required to meet before operating the 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 UPSHIFT or DOWNSHIFT or hold the transmission in a specific gear
^ TCC - Directs the PCM to LOCK or UNLOCK the torque converter clutch
GEAR - 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 UPSHIFT or DOWNSHIFT concerns that have been identified by the customer. 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 the OSC has commanded until the OSC commands another gear or the OSC is canceled.
The OSC functions for the GEAR parameter allow the technician to choose the following options:
^ 1 - Directs the PCM to command 1st gear
^ 2 - Directs the PCM to command 2nd gear
^ 3 - Directs the PCM to command 3rd gear
^ 4 - Directs the PCM to command 4th gear
^ XXX - Cancels the OSC command for GEAR and returns to normal operation
The vehicle requirements MUST BE MET when SENDING the OSC value for GEAR. If the vehicle requirements are NOT MET when SENDING the OSC value, an ERROR MESSAGE will appear. When the ERROR MESSAGE is received, OSC is aborted and must be restarted. After SENDING the OSC value, if the vehicle requirements are no longer met, the ERROR MESSAGE will NOT appear, but the PCM will cancel the OSC value. The OSC value XXX may be sent anytime to cancel OSC.
It is recommended to use the TCC parameter in OSC to first turn OFF the torque 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, 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 clutch changing or the actual gear change.
The vehicle requirements for SENDING an GEAR value are as follows:
^ Engine is running
^ Gear selector is in OVERDRIVE
^ Vehicle speed is greater than 2 MPH
^ Vehicle speed must be lower than 30 MPH to command a downshift to 1st gear
^ Vehicle speed must be lower than 60 MPH to command a downshift to 2nd gear
^ Vehicle speed must be lower than 90 MPH to command a downshift to 3rd gear
^ Vehicle speed must be greater than 30 MPH to command an upshift to 4th gear
TCC - DRIVE MODE
This OSC function is used to test whether the torque converter clutch is LOCKING and UNLOCKING correctly.
The OSC functions for the TCC parameter allows the technician to choose the following:
^ ON - Commands the TCC solenoid ON (100% duty cycle) to LOCK the torque converter clutch
^ OFF - Commands the TCC solenoid OFF (0% duty cycle) to UNLOCK the torque converter clutch
^ XXX - Cancels the OSC command for TCC and returns to normal operation
The vehicle requirements MUST BE MET when SENDING the OSC value for TCC. If the vehicle requirements are NOT MET when SENDING the OSC value, an ERROR MESSAGE will appear. When the ERROR MESSAGE is received, OSC is aborted and must be restarted. After SENDING the OSC value, if the vehicle requirements are no longer met, the ERROR MESSAGE will NOT appear, but the PCM will cancel the OSC value. The OSC value XXX may be sent anytime to cancel OSC.
The vehicle requirements for SENDING the TCC value OFF are as follows:
^ Engine is RUNNING
^ Gear selector is in OVERDRIVE
^ Vehicle speed greater than 2 MPH
The vehicle requirements for SENDING the TCC value ON are as follows:
^ Engine is RUNNING
^ Gear selector is in OVERDRIVE
^ Vehicle speed greater than 2 MPH
^ Transmission Fluid Temperature (TFT) is between 60°F and 240°F
^ Brake is OFF when vehicle is below 20 MPH
^ Not an excessive load of the engine
^ Not during an UPSHIFT or a DOWNSHIFT
^ Engine speed is greater than 1500 RPM
Using Output State Control (OSC) and Accessing PIDs
To confirm that the OSC value was sent by the diagnostic tool and the PCM has accepted the OSC substitution, a corresponding PID for each OSC parameter must be monitored. Additional PIDs should be monitored to help the technician adequately diagnose the transmission.
List of OSC parameters and their corresponding PID