My truck is stuck in first gear. Neighbor has a computer that was plugged into the truck. It did not pick up any codes. The shaft speed output sensor verses what the speedo was of by half. He replaced the speed sensor, but nothing has changed. What is the next step?

 

Did you do anything to your truck lately?

 

None. I am wondering if the guy I was paying to up keep the truck was even doing anything. He is out of business now. I am going to drop the pan and check for particles and check the bands. Any suggestions.

 

Is that an 07 5.9 or an 07 6.7? If it is the 5.9 how fast did you go before deciding it was stuck in 1st. Or do you mean that you can't manually shift from 1st up to second and on up into park.
If it is the first, try going fast enough to drive past 2nd and into third. The Low Reverse band applies to give you second. Does it feel like it is trying to go into second but slipping. It's possible the band adjustment is too loose and won't apply the band for second. In which case a quick adjustment will fix it.
If it is the other case, where the shift lever is stuck in the 1st gear position, you may have dropped the band adj linkage above the valve body. This too is not hard to fix, but more work and messy. You have to drop the pan, drop the VB and re assemble the band strut.