No downshifting

[matuva]

Hey all,

I have some problem fixing out a 6.5l not downshifting when put under load. I run the scan tool but code show.

The truck runs fine, no other problem other than that.

Simple fact is that when you climb a hill, it lags, smokes a lot, as it doesn't kick down. You have to manually downshift to 3rd to get it breathe and run better.

Any idea?

 

[ak diesel driver]

is it stock or does it have a tune? IIRC the pcm uses APP,RPM, and probably trans input for shifting

 

[matuva]

Stock one ak. That did happen after the guy put his truck at a mechanic to solve a power steering pump issue

???

 

[JiFaire]

Is the TCC unlocking, Al? IIRC, it wont shift down (OD --> 3rd) if it doesn't unlock...

 

[matuva]

Jim, the TCC probably stays locked, as you suggest. As there's no code, I don't know where to look at. May be an electrical issue?

 

[WarWagon]

Does it downshift when you floor it?

If so you may have a turbo boost issue, vacuum line off, etc. Thus you get a high load and no boost to run well.

 

[Michaeljp86]

The TCM uses the speed from the transmission sensor and the engine rpm sensor along with the TPS to determine if the engine is bogging down. Something must be telling it that its not bogging down.