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Scan Tool Testing and Procedures




Output State Control (OSC) Mode

Description

Output state control (OSC) on a service diagnostic tool, such as the NGS or WDS, allows the technician to control the main functions of the transmission such as gear shifts, torque converter clutch or the shift solenoids quickly and easily. For example, the OSC allows the technician to command the torque converter clutch to engage while monitoring the actual converter slip or disengage the torque converter clutch while testing the transmission upshifts or downshifts. The technician may command a shift solenoid to turn ON or OFF while carrying out the electrical tests, while measuring voltage or current with an inductive pickup.

Procedure

The OSC has 2 modes of operation for the transmission:

- Service Bay Mode
- Drive Mode

In order to operate the OSC in the drive mode, no diagnostic trouble codes (DTCs) related to the transmission range (TR) sensor, turbine shaft speed (TSS) sensor, output shaft speed (OSS) sensor or the SSPC-A (coast clutch), SSPC-B (overdrive clutch), SSPC-C (intermediate clutch), SSPC-D (direct clutch), SSPC-E (low reverse) and PC-A (line pressure) solenoids may be present. Carry out the KOEO on-demand self test and retrieve continuous codes to identify any codes that are present.

OSC For Transmission - Service Bay Mode

The service bay mode is used to test various transmission components and functions when the vehicle is in the service bay. The service bay mode is used when carrying out electrical pinpoint tests and hydraulic pressure tests. Each OSC function has a unique set of vehicle operating requirements or vehicle states that the technician is required to meet before the powertrain control module (PCM) will allow the OSC to operate. The service bay mode is used in the following 3 vehicle states:

Vehicle State No.1
- The Vehicle State No.1 requirements for sending an OSC value as follows:
- Key on
- Engine not running
- Gear selector in PARK or NEUTRAL

Vehicle State No. 1 is used when carrying out electrical pinpoint tests. The following transmission components may be controlled using the OSC in Vehicle State No. 1:

- SSE_AMP - Controls the current to the SSPC-E (low and reverse clutch) solenoid.
- SSD_AMP - Controls the current to the SSPC-D (direct clutch) solenoid.
- SSC_AMP - Controls the current to the SSPC-C (intermediate clutch) solenoid.
- SSB_AMP - Controls the current to the SSPC-B (overdrive clutch) solenoid.
- SSA_AMP - Controls the current to the SSPD-A (coast clutch) solenoid.
- TCC_AMP - Controls the current to the torque converter (TCC) clutch solenoid.
- LINEDSD - Controls the commanded pressure, which in turn controls the current to the PC-A (line pressure control) solenoid.

The vehicle requirements must be met when sending the OSC value for SSPC-E, SSPC-D, SSPC-C, SSPC-B, SSPC-A, TCC and PC-A solenoids. If the vehicle requirements are not met when sending the OSC value, an error message may appear. When the error message is received, the 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 OSC value will be canceled by the PCM (monitor corresponding PID). The OSC value XXX may be sent anytime to cancel the OSC.

Vehicle State No. 2
- The Vehicle State No. 2 requirements for sending an OSC value are as follows:
- Engine running
- Exception: Engine running greater than 1,000 rpm to control LINEDSD
- Gear selector in PARK or NEUTRAL

Vehicle State No. 2 is used when carrying out electronic pressure control tests and electrical pinpoint tests. The following transmission components may be controlled using the OSC in Vehicle State No. 2:

- SSE_AMP - Controls the current to the SSPC-E (low and reverse clutch) VFS solenoid.
- SSB_AMP - Controls the current to the SSPC-B (overdrive clutch) solenoid.
- SSA_AMP - Controls the current to the SSPC-A (coast clutch) solenoid.
- TCC_AMP - Controls the current to the torque converter (TCC) clutch solenoid.
- LINEDSD - Controls the commanded pressure, which in turn controls the current to the PC-A (line pressure control) solenoid.

The vehicle requirements must be met when sending the OSC value for SSPC-E, SSPC-B, SSPC-A, TCC and PC-A solenoids. If the vehicle requirements are not met when sending the OSC value, an error message may appear. When the error message is received, the 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 OSC value will be canceled by the PCM (monitor corresponding PID). The OSC value XXX may be sent anytime to cancel OSC.

Vehicle State No. 3
- Vehicle State No. 3 requirements for sending an OSC value are as follows:
- Engine running
- Gear selector in overdrive
- Vehicle not moving

Vehicle State No. 3 is used when carrying out electronic pressure control tests and electrical pinpoint tests. The following transmission components may be controlled using the OSC in Vehicle State No. 3:

- SSD_AMP - Controls the current to the SSPC-D (direct clutch) solenoid.
- SSC_AMP - Controls the current to the SSPC-C (intermediate clutch) solenoid.

The vehicle requirements must be met when sending the OSC value for SSPC-D and SSPC-C solenoids. If the vehicle requirements are not met when sending the OSC value, an error message may appear. When the error message is received, the 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 OSC value will be canceled by the PCM (monitor corresponding PID). The OSC value XXX may be sent anytime to cancel OSC.

The OSC options to control SSA_AMP, SSB_AMP, SSC_AMP, SSD_AMP, SSE_AMP, TCC_AMP for solenoids in service bay mode are as follows:

- 0 - Commands PCM to control current to zero amps.
- 0.25 - Commands PCM to control current to 1/4 amp to 250 milliamps.
- 0.50 - Commands PCM to control current to 1/2 amp or 500 milliamps.
- 0.75 - Commands PCM to control current to 3/4 amp or 750 milliamps.
- 1.0 - Commands PCM to control current to 1 amp or 1,000 milliamps.
- XXX - Cancels OSC and allows the PCM normal control of the VFS solenoids.

Controlling the solenoids allows the technicians to measure the circuit current using an inductive pickup or to measure the circuit voltage when carrying out electrical tests.

The OSC options to control LINEDSD for line pressure in service bay mode are as follows:

- 20 - Commands PCM to control line pressure to 20 psi.
- 60 - Commands PCM to control line pressure to 60 psi.
- 100 - Commands PCM to control line pressure to 100 psi.
- 140 - Commands PCM to control line pressure to 140 psi.
- 180 - Commands PCM to control line pressure to 180 psi.
- 220 - Commands PCM to control line pressure to 220 psi.
- 260 - Commands PCM to control line pressure to 260 psi.
- 300 - Commands PCM to control line pressure to 300 psi.
- XXX - Cancels OSC and allows the PCM normal control of the line pressure.

The OSC allows the technician to control the commanded line pressure instead of the PC-A current. The PCM will command a specific current to the PC-A solenoid when requesting a particular OSC line pressure. Using OSC to control the line pressure allows the technician to accurately test the electronic pressure control system by comparing the OSC command line pressure to the actual line pressure indicated on the gauge. This will aid in testing for pump capacity and the ability of the PCM to electronically control the pressure. The technician may also measure the circuit current using an inductive pickup or to measure the circuit voltage when carrying out an electrical test on the line pressure (PC-A) solenoid.

OSC For Transmission - Drive Mode

The drive mode allows control of 3 transmission functions. Each function has a unique set of vehicle operating requirements that the technician is required to meet before the PCM will allow OSC to operate. The drive mode allows the technician to carry out the following functions:

- TCC_OSC - Commands the PCM to engage or disengage the torque converter clutch.
- GEAR_OSC - Commands the PCM to upshift or downshift.
- HRSH_SFT - Commands a higher pressure value during an upshift.

The OSC options to control TCC_OSC to engage or disengage the torque converter clutch in drive mode are as follows:

- OFF - Commands the PCM to keep the torque converter clutch from engaging.
- ON - Commands the PCM to engage the torque converter clutch.
- XXX - Cancels OSC and allows PCM normal control of the torque converter clutch.

Controlling the torque converter clutch will assist the technician in testing the torque converter for engagements and disengagements. Also, the technician is better able to evaluate upshifts and downshifts by using the OSC to keep the torque converter clutch from engaging.

The vehicle requirements must be met when sending the OSC value for TCC_OSC. If the vehicle requirements are not met when sending the OSC value, an error message may appear. When the error message is received, the OSC is aborted and must be restarted. After the OSC value for TCC_OSC is sent, if the vehicle requirements are no longer met, the error message will not appear but the OSC value will be canceled by the PCM (monitor corresponding PID). The OSC value XXX may be sent anytime to cancel OSC.

The vehicle requirements for sending the TCC_OSC value OFF are as follows:

- Engine running
- Gear selector in overdrive
- Vehicle speed greater than 5 Km/h (3 mph)

The vehicle requirements for sending the TCC_OSC value ON are as follows:

- Engine running
- Gear selector in overdrive
- Vehicle speed greater than 5 Km/h (3 mph)
- Transmission fluid temperature (TFT) between 17�C and 135�C (60�F and 275�F)
- Brake is off when vehicle speed is below 32 Km/h (20 mph)
- Not an excessive load on the engine
- Engine speed greater than 1,300 rpm

The OSC options to control GEAR_OSC to shift the transmission in drive mode are as follows:

- 1 - Commands PCM to shift to 1st gear auto.
- 2 - Commands PCM to shift to 2nd gear auto.
- 3 - Commands PCM to shift to 3rd gear auto.
- 5 - Commands PCM to shift to 5th gear auto.
- 6 - Commands PCM to shift to 6th gear auto.
- XXX - Cancels OSC and allows PCM normal control of upshifts and downshifts.

Controlling the gear changes will assist the technician in testing the various clutches and bands and determine whether the transmission is slipping in any particular gear. The OSC will command the PCM to upshift or downshift depending on the gear the technician selects. The transmission will remain in the OSC gear selected until another OSC gear is selected or until OSC is cancelled.

NOTE: Fourth gear is not allowed to be commanded when using OSC.

The vehicle requirements must be met when sending the OSC value for GEAR_OSC. If the vehicle requirements are not met when sending the OSC value, an error message may appear. When the error message is received, the OSC is aborted and must be restarted. After the OSC value for GEAR_OSC is sent, if the vehicle requirements are no longer met, the error message will not appear but the OSC value will be canceled by the PCM (monitor corresponding PID). The OSC value XXX may be sent anytime to cancel OSC.

It is recommended to use TCC_OSC to first turn off the torque converter clutch before testing the transmission gear changes. This will allow the technician to evaluate only the gear changes. If the torque converter clutch is NOT turned OFF, the PCM will command the torque converter clutch to engage. This could make it difficult for the technician to determine whether an abnormal shift is the result of the torque converter clutch or the actual gear change.

The vehicle requirements for sending a GEAR_OSC value are as follows:

- Engine running
- Gear selector in overdrive
- Vehicle speed greater than 5 Km/h (3 mph)

The OSC options to control HRSH_SFT to moderately increase line pressure to test for firmer engagements and shifts in drive mode are as follows:

- OFF - Commands PCM to use normal pressure and not to increase hydraulic pressure.
- ON - Commands PCM to moderately increase the hydraulic pressure.
- XXX - Cancels OSC.

Setting HRSH_SFT allows the technician to moderately increase the pressure when carrying out engagements such as park-to-reverse, neutral-to-reverse, etc., and when carrying out automatic upshifts. This will provide additional diagnostic information to help the technician determine whether the electronic pressure control system is providing at least limited control (a normal shift would become firmer) and/or whether a hydraulic circuit that may have abnormally low pressure (due to such things as low fluid level, leaky clutch, etc.) resulting in a soft shift, becomes normal when increasing the pressure.

The vehicle requirements must be met when sending the OSC value for HRSH_SFT. If the vehicle requirements are not met when sending the OSC value, an error message may appear. When the error message is received, the OSC is aborted and must be restarted. After the OSC value for HRSH_SFT is sent, if the vehicle requirements are no longer met, the error message will not appear but the OSC value will be canceled by the PCM (monitor corresponding PID). The OSC value XXX may be sent anytime to cancel OSC.

Using Output State Control (OSC) and Monitoring PIDs

To confirm that the OSC value was sent by the NGS or WDS and the PCM has accepted the OSC command, a corresponding PID for each OSC parameter must be monitored. After sending the OSC value, the corresponding PID value should be the same as the OSC value. 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.

PID Chart

NOTE: The pressure switch PIDs in this table will not be applicable to all vehicle applications. Some vehicles will not have the pressure switches installed in the valve body.












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