Description & Operation: Notes

The first step in diagnosing any driveability concern is verifying the customer's complaint with a test drive under the conditions the concern reportedly occurred. Before entering self-diagnostics, perform a careful and complete visual inspection. Most transmission control concerns result from mechanical breakdowns or poor electrical connections.

Input signals from sensors are sent to the Powertrain Control Module (PCM). The PCM controls shift or converter clutch application. The PCM can also determine line pressure needed to optimize shift feel.

Five electronic solenoids perform following functions:

• 3 on/off solenoids for shifting.
• One Pulse-Width Modulator (PWM) solenoid for Torque Converter Clutch (TCC) control.
• One Electronic Pressure Control (EPC) solenoid for line pressure control.

The PCM has built-in self-diagnosis, fail-safe code and warning code display for the main input sensors and solenoid valves.