Transmission cooler
I was in 4 low going up Bell Mountain in Georgia. I was about 1/2 mile into the trip and 2 people also had the same light the other in normal drive and the other was the same as me. It was a gravel road before any real off reading.
Overheating on a steep incline is probably not anything wrong with your transmission. You might want to try a lower gear next time too since overheating is common if the torque converter doesn't lock. Otherwise, a cooler is your best option.
-Deke
-Deke


