Downshifts to low at highway speeds

[Robert Rick]

I have a 2008 Silverado, 6 speed auto, 2500 HD, 2WD...while driving at higway speeds, the truck will literally downshift straight into low gear. The back wheels all but lock up! Had it to 2 different dealers who has told me that these symptoms were impossible! Yet the truck just does it at random times, but never when a mechanic is driving it. When it happens I turn off the ignition and restart the truck and its fine for a while. If i dont figure this out someone is going to get killed

[cmysstailights]

I have a 2008 Silverado, 6 speed auto, 2500 HD, 2WD...while driving at higway speeds, the truck will literally downshift straight into low gear. The back wheels all but lock up! Had it to 2 different dealers who has told me that these symptoms were impossible! Yet the truck just does it at random times, but never when a mechanic is driving it. When it happens I turn off the ignition and restart the truck and its fine for a while. If i dont figure this out someone is going to get killed

I had mine after 1.5 hrs of driving go from 6 to 4th and stay in 4th until i shut the truck off and then turned it back on. 15 2500

Sent from my SM-G960U using Tapatalk

[Robert Rick]

Did you ever find out what caused it?

[Formulabruce]

Connector at speed sensor on Trans, or the TCM.

[cmysstailights]

Did you ever find out what caused it?

Have warranty so trans is being rebuilt all new.

Sent from my SM-G960U using Tapatalk