Having problems with your 2001 GMC Sierra 2500HD ?
Transmission shifts hard,and shifts in&out of overdrive alot
Check a part thats mounted on the drivers side of the transmission called the inter lock switch It could be a shift cabe adjustment but the cable has to move the interlock switch every time you shift the vehicle and is the most likely part to start binding and causeing shift problems and a number of other issues with control functions with vcm operation and false code readings set off
Repair Help & Product Troubleshooting for 2001 GMC Sierra 2500HD
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