MTPKTS
New Member
Hello All!!! New time subscriber but a long time reader. I have been all over this site trying to find some direction with my transmission problem but I feel like I am striking out. Any Help would be appreciated.
1997 GMC 2500 4 WD 6.5 TD 4L80E.
The truck drives fine when cold and shifts through all gears as it should Once the vehicle warms up (15-20) and under normal driving all is fine until I attempt to go up a slight grade or stomp on the accelerator and the truck down shifts from OD to 3, usually around 50 mph. When it down shifts is slips and revs real high, like I pushed the clutch in. If I manual shift the trans into 3 it drives without missing a beat. I have no warning lights on and this started out of the blue with no gradual signs. Any help with this is greatly appreciated.
1997 GMC 2500 4 WD 6.5 TD 4L80E.
The truck drives fine when cold and shifts through all gears as it should Once the vehicle warms up (15-20) and under normal driving all is fine until I attempt to go up a slight grade or stomp on the accelerator and the truck down shifts from OD to 3, usually around 50 mph. When it down shifts is slips and revs real high, like I pushed the clutch in. If I manual shift the trans into 3 it drives without missing a beat. I have no warning lights on and this started out of the blue with no gradual signs. Any help with this is greatly appreciated.