Ended up needing a new/rebuilt transmission and as soon as I drove off the repair shop lot the truck momentarily went into limp mode and then back out. It has done this several times and one time the trans hot light came on. I get an error code of P720 - does anyone know what this means in conjunction with the new/rebuilt transmission? Thank you for your help!

 

Output speed sensor open, possible wiring or sensor.

 

Thank you - would it cause it to go into momentary limp mode?

 

Was trans cooler back flush done? If the cooler is plugged trans will not last long. Metal contamination will also make its way back into the valve body causing problems. Check the Powertrain Control Module (PCM) terminals for corrosion, damage, or terminal push out. If ok then most likely the output speed sensor. Located in the overdrive gear case.

 

Took the truck back to the transmission shop and the output speed sensor had debris on the tip. They tell me they did a cooler flush, so I'm not sure why there was debris there. Anyway seems to run fine now and so far no codes. Thank you for the troubleshooting help!