Electronic Control System
Electronic Control SystemFunctional Diagram
The electronic control system consists of the transmission control module (TCM), sensors, switches, and solenoid valves. Shifting is electronically controlled for comfortable driving under all conditions.
The TCM inputs signals from the ECM, sensors and switches, perform processing data, and outputs signals for automatic transmission control system. The A/T control system, which includes the shift control, pulley pressure control, start clutch pressure control, reverse inhibitor control, and creep aid control, is stored in the TCM. The TCM actuates the pulley control solenoids to control the pulley control valves A and B shifting transmission pulley ratios.
Pulley Pressure Control/Shift Control
To reduce belt slippage and increase belt life, the TCM calculates signals from the sensors and switches, and actuates the pulley pressure control solenoid valves to maintain optimum pulley pressure. When the pulley ratio is low (low vehicle speed), high hydraulic pressure works on the movable face of the driven pulley and reduces the effective diameter of the driven pulley, and a lower hydraulic pressure works on the movable face of the drive pulley to eliminate the steel belt slippage. When the pulley ratio is high (high vehicle speed), high hydraulic pressure works on the movable face of the drive pulley and reduces the effective diameter of the drive pulley, and a lower hydraulic pressure works on the movable face of the driven pulley to eliminate the steel belt slippage.
The TCM compares actual driving conditions with memorized driving conditions to control shifting, and instantly determines a drive pulley ratio from various signals sent from sensors and switches. The TCM activates the CVT drive pulley pressure control valve to control pulley pressure to the pulleys. The drive pulley drives the driven pulley via a steel belt at varying ratios ranging from 2.441 to 0.407 in the [D] position.
Start Clutch Pressure Control
The hydraulic-controlled start clutch controls smooth starting-off and creeping in the D, L, and R positions like a torque converter. The TCM inputs signals from the ECM, sensors switches actuates the start clutch pressure control valve to regulate the clutch reducing pressure, and the clutch reducing pressure controls the start clutch.
Creep Aid Control
The Creep Aid System prevents the vehicle from moving backwards when the vehicle starts off on an ascending slope after the brake pedal is released.
When the vehicle comes to a stop, the engine is stopped by the auto-stop system under certain conditions. The start clutch is released because the ATF pump does not operate when the engine is stopped.
With the auto-stop system, when the vehicle comes to a stop with the brakes applied on an ascending slope, the TCM turns the creep-aid system solenoid valves A and B ON. This maintains the brake pressure, applied during the stop, to the brakes. When the engine restarts, the TCM turns the creep-aid system solenoid valves A and B OFF releasing the brake system pressure, allowing the vehicle to creep.
Electronic Controls Location
TCM Electrical Connection
TCM Inputs and Outputs
TCM Connector Terminal Locations
TCM CONNECTOR A (26P)
TCM CONNECTOR A (26P)
TCM CONNECTOR B (22P)
TCM Connector Terminal Locations
TCM CONNECTOR B (22P)