What is an Automatic Trans Shift Cable?
Though many modern vehicles have moved away from transmission shift cables and adapted transmission shift motors in their place, many vehicles still come equipped with transmission shift cables to change the operating range of the transmission. The operating range does not refer to the gear the transmission is currently in, it refers to the set of gears the transmission is allowed to move through when set to a specific setting by the user. These settings include park, reverse, neutral, drive, and any lower ranges. In order to select these ranges on the transmission, the gear selector in the vehicle is connected to the automatic transmission shift shaft by a transmission shift cable.
How does an Automatic Trans Shift Cable work?
When the gear selector is moved, it pushes or pulls the cable the exact amount needed in order to place the transmission shift shaft dead center in that range. The automatic transmission handles all gear changes after that point, and the driver can sit back, and focus on driving. In many transmissions, especially for dual clutch transmissions with shift cables, the shift cable does not have a hard setting on the transmission, and the only resistance felt is a feature of the gear selector assembly. These transmissions will recognize the position of the shift shaft based on the transmission position sensor.
What are the symptoms of a bad Automatic Trans Shift Cable?
There are three ways the automatic transmission shift cable can fail, and they will give slightly different symptoms. If the cable stretches, it is likely to break soon, but the transmission should still function. Though the transmission may slip into its drive range after the gear selector is moved to that range, the stretched cable will likely require the gear selector be shaken or moved just past the desired range for engagement. For shift cables with corrosion within the sheath, the shifter may become difficult or impossible to move. Finally, a broken shift cable will provide no resistance in the gear selector lever, and the transmission will not move out of the current range. If that range is not park or neutral, the engine will not start, and the parking brake must be applied. The latter applies to neutral as well.