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 park/neutral position (PNP) switch transmits the information which range includes the shift lever of the automatic transmission (A/T) to the starter and transmission control module (TCM).
| • | It is possible for the PNP switch to start an engine in park (P) and neutral (N). |
| • | 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 ON and OFF by the control signal from the transmission control module (TCM). Combinations of two solenoids, SS1 (2) and SS2 (1) changes the gear ranges.
Timing Solenoid
The timing solenoid (1) is installed directly in the valve body. The solenoid operates ON/OFF by the control signal from transmission the control module (TCM).
Lock-Up Solenoid
The lock-up solenoid (1) is installed in the valve body. It receives control signal from the transmission control module (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 pressure control solenoid (PCS) (1) is located inside the valve body and regulates the transmission's fluid pressure system. It is internally grounded in the transmission control module (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 transmission fluid temperature (TFT) sensor (1) provides the transmission control module (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 input shaft speed (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 the signal to the transmission control module (TCM).
Output Shaft Speed (OSS) Sensor
The output shaft speed (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.
