Hello, I'm new here, so hopefully I'm doing it right I have a 99 f-350 crew cab 4x4 powerstroke. 200k, had the tranny rebuilt about a year ago. Ever since then, when it shifts into overdrive it comes in and out until I let off the pedal and accelerate again. the problem has gotten worse to the point my OD light was flashing. I sent it in under warranty and guess what???? Nothing is wrong with it. This was the third time in a year that they have had it with a bunch of BS answers every time. Any help would be much apreciated. I do have access to factory scanner and snap-on scanner, all data looks OK?

 

Check the wire harness in the shifter...

Do you have a chip or any other mods to it? Are you sure its shifting in and out of OD and not locking and unlocking the TC?

 

Thanks for the reply.... I do have superchip. bought it after the problem started, no different with or without. Probably is the torque converter locking and unlocking. In town if I start up a hill from a stop it will do it in 3rd gear also. What were your thoughts on the shifter wiring? The on and off button seems to be functioning correctly? I have also tried map sensor, tps, rear diff speed sensor.... Now that I got it back from the shop the abs light is on and the speedo is in and out??? front hub is bad, that accounts the abs light, but not the speedo, that would be like a diff sensor but its new

 

Check the brake lite switch,when stepping on the brake pedal it disengauges the tourque converter.It could just need to be adjusted so when you hit a bump it dosent trip for a second.Try driving along with it locked and tap the brake with your other foot and see if it feels the same

 

so when your riding along say 2200 rpms, and you hit the brakes, its normal for the rpms to drop to 1900 or so for an instant??? my 01 has done that since i got it and i thought something was wrong with it but always forget to ask you guys!!!

 

I have experimented with that... I do think its the converter locking and unlocking, but have tested the boo and all is right with it. It is only doing it on accel.

 

have you checked your grounds at the batteries any comunication on a ground circut can make a big headache

 

i had the same problem.. it was the sprag in my case..