OSC-Transmission Drive Modes

OSC - Transmission DRIVE MODES
The DRIVE MODE allows control of three transaxle parameters. Each mode/parameter has a unique set of vehicle operating requirements that the technician must meet before being allowed to operate OSC. The recommended procedure, when using the DRIVE MODE, is to control one parameter at a time.
The DRIVE MODE allows the technician to carry out the following functions on the transaxle:
- GEAR - allows upshifts or downshifts.
- TCC - engages or disengages the torque converter clutch.
- FIRM_SFT - commands a higher control pressure during upshift only.

Electronic Pressure Control solenoid A (EPC) for this transaxle can not directly be controlled during DRIVE MODE testing. Pressures may be raised during an upshift via the firm shift control function (FIRM_SFT).

GEAR in DRIVE MODE
This OSC function is used to test the transaxle shift functions.

NOTE: When the technician commands 1St gear during OSC mode, engine braking is automatically activated for 1st gear. Be aware that normal transaxle operation does not use engine braking in 1st gear.

The OSC function for the GEAR parameter allows the technician to choose the following options:
- [1] - PCM selects 1St gear.
- [2] - PCM selects 2nd gear.
- [3] - PCM selects 3rd gear.
- [4] - PCM selects 4th gear.
OSC "GEAR" Mode operates ONLY when:
- VSS and TR sensor are operational.
- No VSS and TR sensor DTCs.
- Engine "ON."
- Transaxle range selector lever in O/D.
- Vehicle speed is greater than 2 mph.
- Gear selected is equal to or below maximum gear available (PID "GEARTOP").
- Maximum vehicle speed for downshift into 1st gear is 25 mph.
- Maximum vehicle speed for downshift into 2nd gear is 60 mph.
- Maximum vehicle speed for downshift into 3rd gear is 127.5 mph.
- Minimum vehicle speed for an upshift to 4th gear is 20 mph.
OSC Command Values:
- [1] - PCM selects 1st gear.
- [2] - PCM selects 2nd gear.
- [3] - PCM selects 3rd gear.
- [14] - PCM selects 4th gear.
- [XXX] - cancels OSC sent value.
- [SEND]- sends the values to PCM.

DRIVE MODE Procedure for GEAR
Follow operating instructions from the NGS menu screen:
- Select "Output State Control."
- Select "Trans-Drive Mode."
- Select "PIDs" to be monitored.
- Monitor all selected PIDs during test.
- Select "Parameters - GEAR."
- Select Value " 1-4."
- Press "SEND" to send command.
- Re-Select Value " 1-4."
- Press "SEND" to send command.
- Select "XXX" to cancel at any time.
- Press "SEND" to send command.

TCC in DRIVE MODE
This OSC function is used to test whether the torque converter clutch is engaging and disengaging correctly.

CAUTION: Technicians should maintain an engine speed of at least 1500 RPM during torque converter engagement testing. Failure to maintain at least 1500 RPM can produce severe vehicle lugging and vibrations depending upon driving/vehicle loading conditions. During output state control testing, the TCC could oscillate between engaged and disengaged mode if engine speed requirements are not followed.

The OSC function for the TCC parameter allows the technician to choose the following:
- TCC - activates TCC OFF and ON.
- [ON] - turns TCC ON.
- [OFF] - turns TCC OFF.
OSC "TCC OFF" DRIVE MODE operates ONLY when:
- VSS and TR sensors are operational.
- No VSS and TR sensor DTCs present.
- Engine ON.
- Transaxle range selector lever in O/D.
- Vehicle speed is greater than 2 mph.
- No transaxle gear shifts are in progress.
OSC "TCC ON" DRIVE MODE operates ONLY when:
- VSS and TR sensors are operational.
- No VSS and TR sensor DTCs present.
- Engine "ON".
- Transaxle range selector lever in O/D.
- Vehicle speed is greater than 2 mph.
- Transaxle in 2nd or higher gear.
- TFT is between 60 and 270F.
- Brake is "OFF" when vehicle speed is below 20 mph.
- Engine speed at least l500 RPM.
- Speed ratio across the converter (PID "TCCRAT") is between 0.70 and 1.05.
- No transaxle gear shifts are in progress.
OSC Command Values
- [OFF] - Turns TCC OFF.
- [ON] - Turns TCC ON.
- [XXX] - Cancels OSC value sent.
- [SEND] - Sends the values to PCM.

Drive Mode Procedure for TCC
Follow operating instructions from the NGS menu screen:
- Select "Output State Control."
- Select "Trans - Drive Mode. "
- Select "PIDs" to be monitored.
- Monitor all selected PIDs during test.
- Select "Parameters - TCC."
- Select "ON" to turn TCC ON.
- Press "SEND" to send command.
- Select "OFF" to turn solenoid OFF.
- Press "SEND" to send command.
- Select "XXX" to cancel at any time.
- Press "SEND" to send command.

FIRM_SFT in DRIVE MODE
This OSC function is used to raise pressure during an upshift to determine whether the pressure control system is functioning correctly. Firmer shifts indicate that the pressure control system works at higher pressure. The best test for isolating pressure control system problems is to carry out the EPC solenoid test it BENCH MODE using a hydraulic pressure gauge.

The OSC functions for the parameter FIRM_SFT allows the technician to choose the following options:
- FIRM_SFT - Activates the firm shift channel.
- [ON] - sets control pressure high for all upshifts (determined by the PCM).
- [OFF]- sets control pressure to normal for all upshifts (determined by the PCM).
OSC "FIRM_SFT" DRIVE MODE operates ONLY when:
- VSS and TR sensor are operational.
- No VSS and TR sensor DTCs present.
- Transaxle range selector lever in O/D.
- Engine "ON."
- Key"ON."
- Vehicle speed greater than 2 mph.
- TCC cannot be forced ON using NGS OSC mode (PID "OSCTCC" not equal to ON)
OSC Command Values
- [ON] - sets control pressure high for all upshifts (determined by the PCM)
- [OFF]- sets control pressure to normal for all upshifts (determined by the PCM)
- [XXX] - cancel OSC for FIRM_SFT
- [SEND] - sends the values to the PCM
DRIVE MODE Procedure for FIRM_SFT.
Follow operating instructions from the NGS menu screen:
- Select "Output State Control."
- Select "Trans - Drive Mode."
- Select "PIDs" to be monitored.
- Monitor all selected PIDs during test.
- Select "Parameters - FTRM_SFT."
- Select "ON" to turn Firm Shift Mode ON.
- Select "SEND" to send command.
- Select "OFF" to turn Firm Shift Mode OFF.
- Select "SEND" to send command.
- Select "XXX" to cancel at any time.
- Select "SEND" to send command.