2018 GMC Acadia electrical system problems

“I get error electric Steering assist reduced or unavailable drive with care at around 84234 miles on my car . Upon looking up problem on Internet it has to do with the Thermostat. I also found where Gm has a bulletin N252508350 which only seems to cover certain vehicles with the same problem. This seems to happen at all different miles driven on vehicles. I don't see how Gm can get away with only fixing certain vehicles with this safety problem when it shuts down the electric steering assist . This problem from what I can find on the internet is common to all years from 2017 up in Acadia with the 3.6L engine . The Thermostats seem to be defective and I feel Gm needs to address this problem for all of these vehicles . Not just for there special bulletin N252508350 which covers some vehicles in 2021with 3.6L engines. If the engine design was like the old engines and easy to replace the Thermostat by just taking out 2 bolts , I would say no problem I will replace it .But when you have to take half the Engine apart just to replace a 20.00 part that is defective that affects the steering of the vehicle, they need to have a safety recall.”

“For the last 6 months, I keep getting a "shift to Park" message on my dashboard indicating that my vehicle is not in park (in which it is). The problem is getting wors, so I called GMC on 5/14/26 to inquire and was informed that my VIN number WAS not include in the resent class action lawsuit for this issue. I then found out by searching myself on line for other complaints that GMC is very aware of this situation and yet refuses to fix the issue free of charge to customers. According to TSB 19-NA-206, t does list my year , make and model of vehicle affected by this faulty part. On 5.15.26, I called the dealership to inquire and was informed that my VIN was not covered under warranty (which I had already known), and that that service I would have to pay lots of money out of pocket for it. The service tech did look in the system and claims (without me even knowing that they had did that repair already....He lied I'm for sure). I informed him well if they did repair that part, and I'm still getting an error message about the same thing, clearly its faulty and the dealership should be responsible for fixing it. This was not the case as I was informed it would have…”

“The contact owns a 2018 GMC Acadia. The contact stated that while the vehicle was parked and turned off, the “Shift-to-Park” warning light illuminated with a continuous audible alert. The vehicle was unable to recognize that the transmission was in park(P). Several attempts were needed to shift to park. The battery was disconnected to turn off the audible alert. The contact stated that the vehicle was previously repaired under an associated recall. During the recall repair, the shifter and wiring harness were replaced with Part Numbers: GM84955381 and GM84733196. The manufacturer was not notified of the failure. The failure mileage was unavailable.”

“The vehicle has experienced repeated electrical and engine-related malfunctions, including random engine shutdowns while driving and random no-start conditions. The thermostat and cooling system failed and were replaced in 2024. Multiple sensors have failed. The braking system remains noisy even after brake replacement. The lane detection safety system does not provide audible alerts. The vehicle is currently operational and available for inspection upon request. How was your safety or the safety of others put at risk? The vehicle has randomly shut off while driving on both highways and city roads in Azle, Texas. This occurred while my two children were in the vehicle. When the engine shut off, there was a risk of losing power steering and braking assist, which could have caused an accident, especially at highway speeds and in traffic. Has the problem been reproduced or confirmed by a dealer or independent service center? The thermostat and cooling system failure were confirmed and repaired by a service center in 2024. Electrical and sensor issues have occurred repeatedly but have not been fully diagnosed or resolved. Brake noise persists despite replacement.…”

“The contact owns a 2018 GMC Acadia. The contact stated that upon parking the vehicle and attempting to release the key from the ignition switch, the key seized inside the ignition switch. The contact stated that either the “Parking Assist” or the “Steering Assist” warning light was illuminated during the failures, and the A/C system became inoperable. The failure had occurred on several occasions. The vehicle was taken to the dealer, where it was diagnosed with Parking Assist and Steering Assist failures. The vehicle was repaired. The manufacturer was notified of the failure. The failure mileage was approximately 98,000. The VIN was not available.”

“Shift to park message has appeared again and the engine will not cut off. First happened in Feb 2020, mileage was 31,143. Took to Dealer and new wiring harness was installed. Had to take back to dealer April 2020 for same problem; shifter assembly was replaced at that time. Shift to park message came back on August 2023. Took back to Dealer and shifter harness replaced again and jumper harness was installed. Mileage was 52,993. Shift to park message has once again appeared, December 2025. Having to put car in park and push engine on/off button numerous times before engine will finally shut off.....sometimes having to unhook battery in order to kill the engine. This will be the fourth time we have had the same recurring issue repaired. My husband read through over half the 352 registered complaints and at least three fourths of them were all about the SHIFT TO PARK problem! As a female, I don't feel safe driving my Acadia not knowing if the engine will cut off or if it's actually in park or if the car will roll. Why can't GM fix this issue!!!!!! They should definitely be held accountable instead of ignoring the complaints!”