Transmisson slips from 3rd to 4th only at low rpms

[Dhouser07]

I have a 2006 6.0 with only 42k
My trannie just started slipping from 3rd to 4th when you go easy on it
when it hits 2grand it slips into neutral
is this a sensor problem?
When you stuff it she doesnt slip so im thinking its a sensor
Any help?

[DangerDog]

Same thing is happening to my 06 6.0 FX4 @ 106k. If I go easy on it, occasionally it slips from 3-4, but no slipping into neutral. If I punch it a bit though it shifts fine.

I imagine this could domino into bigger probs if it doesn't get resolved.

[Dhouser07]

Yah when I stuff it she shifts fine. I haven't been able to figure it out yet.

[makaveli200369]

How's the fluid looking? Is it burnt?

[nylyon]

Mine had a little slip, but it has completely gone away after I got the most recent flash for the truck. All the shifts feel firmer after that. My previous flash was the version which cycled the injectors for 30 seconds after shutdown.

[Dhouser07]

Fluid is fine. Whats the deal with the flash?