2018 Gmc Sierra 1500 Cruise Control Problems

THE SPEED OF THE TRUCK WILL NOT INCREASE. THE RPMS GOES REALLY HIGH AND THE TRUCK WILL NOT MOVE INTO THE NEXT GEAR. THE REAR END OF TRUCK VIBRATES. I TOOK THIS TO THE DEALER AND WAS TOLD IT IS THE TRANSMISSION FLUID IS FAULTY. THE CHECK ENGINE LIGHT DOES COME ON. I DID NOT HAVE THE NEW TRANSMISSION FLUID CHANGED BECAUSE DEALER SAID IS COST $300 FOR THE FLUID AND $100 FOR THE LABOR AND $168 FOR THE DIAGNOSTICS. SO I STILL HAVE THE SAME PROBLEM. ALSO TOLD YOU CAN NOT PURCHASE THIS TRANSMISSION FLUID NO WHERE BUT GMC.

Vehicle suddenly went into Reduced Engine Power while driving in heavy traffic. Vehicle immediately began to slow down and although there was some throttle response it was difficult to maneuver through traffic to get to the side of the road. This event happened around the 31,000 mile mark. The Reduced Engine Power message came on, but I do not remember hearing an audible alert. Being a 40 year Automotive Technician for GM, I am familiar with pulling codes and replacing parts. I called the dealership to see if this was covered by warranty and was told no. After pulling the codes, I personally replaced the Throttle Body Sensor and the Accelerator Pedal Assembly, but the vehicle continued to go into Reduced Engine Power mode. I took the vehicle into the dealership and they diagnosed the cause as a corroded connector. The connector was replaced and the vehicle was returned to me. After a little over one month and less than 1,000 miles the vehicle is once again going into Reduced Engine Power mode. I can have my vehicle available for inspection if necessary.