Drives like tow/haul update

[bigchevyz71]

So Over the weekend the truck started shifting and driving like in tow/haul I hadn’t dogged it or anything it started at a stoplight. The dealer told me I need new batteries because it was throwing a lack of communication code does this make sense or could this be dealer nonsense? 

[dewfpo]

It doesn't make sense to me. What's your battery voltage, engine off and engine running after a few minutes?

 

DEWFPO

[garagerog]

How old are your batteries?  When you replaced them previously were they  both replaced at the same time?  And finally did your dealer load test your current batteries or just come up with that after doing the diagnostic?

[newdude]

If any of the modules see a loss of power or low voltage, they can drop out and cause communication issues.  I'd pull your batteries and have them tested. 

[bgbdwlf2500]

Change the spin on and check color of fluid

[bigchevyz71]

6 hours ago, garagerog said:

How old are your batteries?  When you replaced them previously were they  both replaced at the same time?  And finally did your dealer load test your current batteries or just come up with that after doing the diagnostic?

 

6 hours ago, garagerog said:

How old are your batteries?  When you replaced them previously were they  both replaced at the same time?  And finally did your dealer load test your current batteries or just come up with that after doing the diagnostic?

4 years ish? At the same time, they did diagnostics and tested them in pretty sure

[bigchevyz71]

5 hours ago, bgbdwlf2500 said:

Change the spin on and check color of fluid

Fluid looks perfect 

[bgbdwlf2500]

On ‎1‎/‎2‎/‎2018 at 7:15 PM, bigchevyz71 said:

Fluid looks perfect 

Did anything get reset? that transmission learns your driving style so if it was reset it may be relearning

[GP9]

The relearning due to driving habits might be part of the cause. I have a 2012 2500 6L. There is a long hill where I put it in tow haul. This keeps the truck in the lower gear, and then I don’t need to ride the brake. It seems like the truck now will hold the shift on a descent, even if I don’t use tow haul. The up shifts seem to be normal, and are not held back to higher rpm, as they would be if in TH mode.