Transmission Control Module (TCM)
The transmission control module (TCM) primarily controls shift points and lockup engagement. It is located on the driver side under the instrument panel.
The transmission is controlled by an electronic shift system. The TCM processes input signals. From the information received, the TCM controls the transmission hydraulic system.
The electronic shift system consists of the following components.
| • | TCM |
| • | Shift solenoids (SS1 and SS2) |
| • | Pressure control solenoid (PCS) |
| • | Lockup solenoid |
| • | Input shaft speed (ISS) sensor |
| • | Output shaft speed (OSS) sensor |
| • | Transmission fluid temperature (TFT) sensor |
| • | Park/neutral position (PNP) switch |
Park/Neutral Position (PNP) Switch
The PNP switch transmits the information which range includes the shift lever of the automatic transmission (A/T) to the starter and TCM.
| • | It is possible for the PNP switch to start an engine in only park (P) and neutral (N) prevention of reckless driving |
| • | The PNP switch makes the backup lamp turn on when reversing. |
| • | It is used for PNP switch to shift control. |
The PNP switch transmits the information by combination of starter and reverse circuit to the vehicle side directly without TCM.
Shift Solenoid No 1, 2 (SS1, SS2)
Two shift solenoids are installed directly in the valve body. The solenoids operate of ON and OFF by the control signal from TCM. Combinations of 2 solenoids, SS1 (2) and SS2 (1) changes gear ranges.
Timing Solenoid
The timing solenoid (1) is installed directly in the valve body. The solenoid operates of ON/OFF by the control signal from TCM. The solenoid change timing valve of inside the valve body, operate hydraulic control with apply and drain of forward clutch.
Lock-Up Solenoid
The lock-up solenoid (1) is installed in the valve body. It receives control signal from TCM.
The lock-up solenoid operates the lock-up valve inside the valve body and controls the torque converter lockup function.
Pressure Control Solenoid (PCS)
The PCS (1) is located inside the valve body and regulates the transmission's fluid pressure system. It is internally grounded in the TCM and operates when it is supplied with battery voltage from the TCM, through the PCS and back to the TCM.
The battery voltage is controlled by a varying current from the TCM.
The strength of the current is a function of the throttle position.
Transmission Fluid Temperature (TFT) Sensor
The TFT sensor (1) provides the TCM with information on the transmission fluid temperature.
The TCM uses information from the TFT sensor to calculate the gear shift points and to engage the torque converter lock-up function.
Input Shaft Speed (ISS) Sensor
The ISS sensor (1) is located on the upper position of the transaxle and detects A/T input speed from the rotation number of the direct clutch drum. They transmit to TCM as a signal.
Output Shaft Speed (ISS) Sensor
The OSS sensor (1) is located on the upper position of the transaxle and detects the vehicle speed from the rotation number of the differential gear.
Shift Control
When the AFT is below the specified 15°C (59°F), 4th up-shift is prevented.
