GMC Sierra 3500 HD Automatic Trans Shift Cable Replacement Cost

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.

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.

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.

Vehicles will a failed or failing automatic transmission shift cable should be repaired right away. While the vehicle can operate if it moves into gear, the chances of breaking the shift cable is high, and this will leave you stranded. In cases where the transmission shift cable breaks between gears, it is likely the transmission will be locked into park, reverse, or neutral, even though the gear selector reads drive or a lower range. This can also be a dangerous situation. The best case scenario is that the cable breaks before the vehicle moves from park, but this will still leave the driver and passengers stranded.

Automatic transmission shift cables are actually known for failure on some models, but the majority will last at least 125,000 to 175,000 miles on average. Vehicles with known issues are generally due to extreme bends in the shift cable, poor sealing of the shift cables causing water intrusion, or issues with binding at the shift shaft or gear selector assembly. These vehicles generally give the stated symptoms in advance, and failures have been recorded before 75,000 miles.

Shift cables are simple to diagnose, especially for a trained technician who has seen them over and over throughout their career. If there is no result to moving the shifter through the ranges, the technician will check for breakage of the cable first. Also, if the gear selector shows great difficulty in shifting through the ranges, the technician will likely disconnect the shift cable to see if there is a change in resistance. Lastly, if the selector does not set the shift shaft dead center of the drive range on the transmission, the technician will adjust the shift cable, and test to see if the condition has been corrected or if the condition has moved to another range. If the condition is not corrected, the automatic transmission shift cable will be replaced.

First, the trim and shift boot will be removed from the console or steering column. This grants access to disconnect the automatic transmission shift cable from the gear selector. Next, the cable is removed from the shift shaft on the transmission or transaxle before it is threaded out of the vehicle body and replaced. The rubber grommet that surrounds the shift cable where it makes entry into the body of the vehicle will be replaced, even if it is not included on the new cable assembly. Once the new cable is threaded in and connected to the gear selector and transmission, the interior trim can be replaced. Finally, if adjustment is possible and necessary, the servicing technician will adjust the cable so the transmission shift shaft position directly correlates to the gear selector position in the vehicle.

We do not recommend replacing a non-adjustable cable with an adjustable cable as a means of compensating for a shift shaft and gear selector that may be out of adjustment. The reason for this is that the malalignment is likely due to wear of the shift shaft bushing of gear selector bushings. If this is the case, even installing an adjustable cable will not correct the issue, and the transmission will not shift true to the gear selector.

Failing to replace the water sealing grommet which surrounds the automatic transmission shift cable will result in water intrusion into the vehicle. For automatic transmission shift cables which exit from the firewall, behind the engine, this will also lead to harsh smells from the engine bay entering the vehicle. It is always necessary to reseal the exit point of the automatic transmission shift cable to prevent these undesirable consequences.

This is a perfect job for a DIY project that takes less than an hour. Diagnostics is as easy as listed above, and replacement requires few tools in most cases. Note, electronic shifters with shift motors installed on the transmissions will not have an automatic transmission shift cable, and failure of the transmission to actuate will certainly require more advanced diagnostics.