Q. Have a o3 ford 6.0 I ran truck low on voltage trying to get home. Was slowing downe to make a turn and the transmission made a clunk and it seemed like it wanted to downshift made the turn and truck died due to low voltage from bad alternator. Repaired charging system all is good there but now if you go from reverse to drive transmission will only shift to 4th great and the tow haul light will flash.if you bring truck to a stop and take off again truck will shift fine but light will still flash until you shut truck off and restart.thinking about having it reflashed but not for sure. - Rick
If the tow/haul light is flashing it means there is a trouble code stored for the transmission. I would have someone with a code reader that can pull that level of codes scan the truck and see what it shows. That might give you a hint as to why it’s doing what it is. It's possible the transmission controller could have been corrupted by the low voltage. The code should tell you for sure.