CONSTRUCTION
The TCM and ECM use the park/neutral position switch and transmission control switch to detect the shift lever position.
The park/neutral position switch sends R and D signals to both the TCM and ECM, and sends P and N signals to the ECM only.
The transmission control switch detects whether the shift lever is in M (S signal), detects the operating conditions of the shift lever "+" (upshift) or "-" (downshift) and sends the SFTU and SFTD signals to the ECM.