To start

TCM receives a signal from vehicle speed sensor, accelerator sensor, inhibitor switch and controls shift and lock-up by solenoid valve. Therefore, input/output signal shall be exactly stable during A/T operation. And, there shall be no problem with valve and solenoid valve for A/T system to normally operate.
It is more difficult to diagnose troubles that occur intermittently rather than continuously. Many intermittent troublescan be caused by electrical connection or wiring failures. In such cases, check thoroughly the relevant circuits and take caution not to replace normal part by mistake.
A visual check only may not find the cause for the errors. A road test with hi-scan or circuit tester connected should be performed.
When there is a trouble with drivability, take a few minutes to talk with customers before checking. Especially, it is expected to obtain information that is helpful to diagnose the intermittent errors.
Find out what symptoms are present and under what conditions they occur using the diagnostic sheet.
Start your diagnosis by looking for conventional errors first. This will help troubleshoot driveability errors on an electronically controlled engine vehicle.