GMC Savana Trans Slip Points to Control Module Issue

Had a nearly identical issue with a 2013 GMC Sierra, seems like these powertrains share similar characteristics. With some mechanical experience, I discovered the symptoms were indeed related to the control module, but not the transfer case itself. The ABS system was sending incorrect signals, triggering multiple fault codes and causing the powertrain malfunction. This made the transmission behave erratically and occasionally forced limp home mode. The fix was surprisingly simple. The workshop ran a diagnostic scan which revealed the ABS module was interfering with transmission signals. They cleared the fault codes and performed a system reset, which resolved the issue completely. Since it was traced back to a warranty-covered component, the repair cost was 0 Euro. Before jumping to transmission repair conclusions, could you share: Are there any warning lights besides traction control? Does the issue happen more when the engine is cold or warm? Have you noticed any unusual ABS behavior when braking? Do you have access to a diagnostic scanner to check for stored codes? This information would help determine if your issue matches what I experienced with the ABS system interference.

Last serviced at 72472KM and the mechanic found multiple fault codes during diagnostics. Running a more thorough transmission diagnostic revealed the gear selector position sensor was faulty, causing incorrect signals to the transmission control module. This explains why the traction control light kept activating and the transmission went into limp mode intermittently. The problem has gotten worse since initial posting. The transmission now consistently shifts roughly between 2nd and 3rd gear, particularly when the engine is warm. Would strongly recommend getting the position sensor checked, as it seems to be a common failure point in this model year.

Thanks for the follow-up on your transmission issues. Your experience mirrors mine completely with the gear position sensor. After my initial ABS-related fix, I also encountered that exact same harsh shifting between 2nd and 3rd when warm, classic symptoms of a failing gear selector position sensor. The transmission control module receives incorrect signals, forcing it into limp mode as a safety measure. The diagnostic trouble codes you mentioned align perfectly with my experience. In my case, the sensor degradation was gradual, starting with occasional rough shifts and progressing to consistent problems. The repair cost for the sensor replacement on my Sierra was around 450 Euro, including labor and diagnostic time. Since fixing it, the transmission has shifted perfectly with no more fault codes or limp mode episodes. For others reading with similar symptoms: Multiple transmission-related fault codes, Harsh shifting between specific gears, Traction control activation, Intermittent limp mode These are strong indicators of a gear selector position sensor issue rather than a major transmission problem. Getting a proper diagnostic scan is crucial before assuming worst-case scenarios.

Your transmission woes really had me worried at first, but Im relieved to share the outcome. After checking the diagnostic fault codes and experiencing worsening symptoms, replacing the gear selector position sensor solved our powertrain malfunction issues completely. No more rough shifting or unexpected limp mode episodes. Total repair came to 450 Euro, much better than a full transmission overhaul. The transmission control module now receives correct signals and shifts smoothly. For anyone else facing similar symptoms with their Savana, especially the rough 2-3 shift and traction control warnings, definitely get the position sensor checked first. Really appreciate everyone who helped diagnose this. The forum advice saved me from potentially unnecessary major repairs and helped pinpoint the actual problem. The truck now shifts perfectly and all fault codes have cleared. Definitely worth taking the time to properly diagnose rather than assuming the worst.