[Agar426]

I realize there are other posts on this topic, and most answers tend to point toward the tranny going out. My problem is intermittent, as it seems able to be reset itself after turning the engine off then on again. Once it sets itself straight, it shifts fine throughout the ride. In other words, it doesn't crop up while driving....it either does it, ,or doesn't.

In most transmissions, the OD gears tend to be the first to go out, but wouldn't that show itself in terms of a slipping tranny, etc? Should I be looking more at the PCM or TPS?

Thank you for any help!

 

[Agar426]

Forgot to mention - The truck isn't throwing any codes/CEL

 

[TransEngineer]

Wouldn't expect this to be an issue in NM in August, but if the sump temp is below a certain level, the Torque Converter Clutch (TCC) will not engage, and the trans will not shift into 6th gear. So if this only happens on a cold start, that might explain it. Although once it warms up a bit, it should engage the TCC (and 6th gear) OK, without having to restart it.

Otherwise, you're correct that this usually indicates an OD clutch on the way out. When it avoids 5th and 6th, if you come to a stop and then take off again (without restarting it), does it shift directly from 1st to 4th, or do you still get 1-2-3-4?

 

[Agar426]

Wouldn't expect this to be an issue in NM in August, but if the sump temp is below a certain level, the Torque Converter Clutch (TCC) will not engage, and the trans will not shift into 6th gear. So if this only happens on a cold start, that might explain it. Although once it warms up a bit, it should engage the TCC (and 6th gear) OK, without having to restart it.

Otherwise, you're correct that this usually indicates an OD clutch on the way out. When it avoids 5th and 6th, if you come to a stop and then take off again (without restarting it), does it shift directly from 1st to 4th, or do you still get 1-2-3-4?

Ok, to answer the last question, the answer is yes, I still get the 1-2-3-4 shifts. Today, I was in it and it shifted fine the entire time, with about 3.5 total hours on the highway.

 

[TransEngineer]

Ok, to answer the last question, the answer is yes, I still get the 1-2-3-4 shifts. Today, I was in it and it shifted fine the entire time, with about 3.5 total hours on the highway.

If you're getting 1-2-3-4, then I think you're probably OK (although I can't explain why it will sometimes avoid 5th and 6th). For max OD clutch life, I would suggest manually downshifting it (to "4") before stomping on it, if you're in 5th or 6th.