EPC in DRIVE MODE:: Notes

This OSC function is used to increase pressures during an upshift or downshift to determine whether the pressure control system is functioning correctly. Harsher shifts indicate that the pressure control system works at higher pressures. The best way to isolate pressure control system problems, is to control the EPC in the bench mode and monitor a pressure gauge.

The OSC functions for the parameter EPC allow the technician to choose the following options:

• 00 - sets EPC pressure to 0 psi.
• 16 - sets EPC pressure to 15 psi.
• 30 - sets EPC pressure to 30 psi.
• 45 - sets EPC pressure to 45 psi.
• 60 - sets EPC pressure to 60 psi.
• 75 - sets EPC pressure to 75 psi.
• 90 - sets EPC pressure to 90 psi.
• XXX - Cancels OSC for EPC.

The vehicle requirements for sending the EPC value in drive mode are as follows:

• Engine is running.
• Range selector lever is in OVERDRIVE.
• Vehicle speed is greater than 3 km/h (2 mph).
• OSC value being sent is greater than what the normal strategy is commanding.

For example: If the PCM is commanding a pressure of 344.75 kPa (50 psi), an OSC value greater than 50 must be sent, sending a value of 60 or 75 would work. If the PCM is commanding 517.125 kpa (75 psi), sending a value of 60 would not work, but sending a value of 90 would. This will make sure that OSC will only send a value greater than what the PCM is commanding, to prevent wear to the transmission due to inadequate pressures.

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 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 OSC value will be canceled by the powertrain control module (PCM) (monitor corresponding PID). The OSC value XXX may be sent anytime to cancel OSC.