Electronic Pressure Control (EPC) Solenoid

DESCRIPTION
- The Electronic Pressure Control (EPC) solenoid is a Variable Force Style (VFS) solenoid. The VFS type solenoid is an electro-hydraulic actuator combining a solenoid and a regulating valve. The Powertrain Control Module (PCM) varies the current to the EPC solenoid.
- This action causes the solenoid to regulate transmission line pressure and line modulator pressure. This is done by producing resisting forces to the main regulator and line modulator circuits. These two solenoids control clutch application pressures.

SYMPTOMS:
- Electronic Pressure Control (EPC) shorted to ground or failed low may result in a false VSS DTC. Diagnose EPC concerns first, then recheck VSS.
- Maximum EPC - high pressure resulting in harsh engagements and shifts.
- Zero EPC - low pressure resulting in no 3rd and 5th gear, slips in 2nd and 4th with high input torque. Alternate firing of engine to limit torque.

DIAGNOSTIC TROUBLE CODES:
P1746*, P1747*

* Output circuit check, generated by electrical conditions.