I have a 2007 Silverado 1500 with 287K miles and the 4.8 Vortec. One day I was driving home when i noticed that the vehicle wouldn’t go past 40 MPH. Transmission temperature had spiked to 234 degrees. The vehicle had no codes whenever that happened and I wasn’t carrying a heavy load. What happened here and any way to repair this issue?
The vehicle had no codes
you need a pretty good scanner to read trans codes.
Anyway, it's most likely shot. I don't recommend repairing transmissions with that mileage. Replace only.
After 18 years and almost 290K miles it would be no surprise for the transmission to be worn out. Has it been serviced regularly? Is there enough fluid? What is the fluid's condition? Is your scan tool able to read manufacturer-specific transmission codes and data?
Automatic transmissions are very complex and there is not a lot that can be done with them by most owners.
