Automatic transmission control unit (AT) Toyota Vista SV40
Model: ECM-AT2
Location: Typically located under the dashboard on the driver’s side.
Functions:
* Controls the operation of the automatic transmission.
* Receives signals from sensors and switches to determine the desired gear shift mode.
* Determines optimal gear shift timing based on input data.
* Provides torque converter lock-up for improved efficiency.
* Provides transmission protection from damage.
Fault codes:
The automatic transmission control unit can store fault codes indicating problems in the transmission system. These codes can be read using a diagnostic scanner.
General fault codes:
* P0700: Malfunction in the transmission control system.
* P0715: Transmission speed sensor malfunction.
* P0730: Faulty transmission.
* P0740: Torque converter problem.
* P0750: Shift solenoid malfunction.
Signs of a faulty automatic transmission control unit:
* Problems with gear shifting.
* Transmission slippage.
* Noise or vibration when shifting gears.
* The engine or transmission warning light comes on.
*Storing transmission related fault codes.
Diagnostics and repair:
Diagnostics of the automatic transmission control unit usually includes the following steps:
* Reading fault codes using a diagnostic scanner.
* Checking input signals to the automatic transmission control unit.
* Checking the output signals of the automatic transmission control unit.
* Checking wiring and connectors.
Repairing the automatic transmission control unit can be difficult and expensive, so it is usually recommended to replace it if it is faulty.