Aisin

[Marion B Butler]

Towing 14K 5th wheel, transmission hunts between 5th and 6th gears in tow/haul mode. Even on level ground. Any experienced replys welcomed.

 

[SnoKing]

Towing 14K 5th wheel, transmission hunts between 5th and 6th gears in tow/haul mode. Even on level ground. Any experienced replys welcomed.

What year is it. SRW or DRW(what gears). A flash fixed a lot of hunting gears on my 2015.

I have 3.42(SRW) and tow in 5th at 60-62 MPH, so in TH it will not shift to 6th until 65 MPH. Mine was hunting between 5th and 4th.

SnoKing

 

[Marion B Butler]

What year is it. SRW or DRW(what gears). A flash fixed a lot of hunting gears on my 2015.

I have 3.42(SRW) and tow in 5th at 60-62 MPH, so in TH it will not shift to 6th until 65 MPH. Mine was hunting between 5th and 4th.

SnoKing

2018 3500 DRW 4.10

 

[Learjet]

the only time I have seen this is at higher elevations...above 5000'. lock out 6th gear with the +- switch on the column.

What was your speed and engine RPM when this occurred?

 

[Marion B Butler]

the only time I have seen this is at higher elevations...above 5000'. lock out 6th gear with the +- switch on the column.

What was your speed and engine RPM when this occurred?

64mph cruise on at 5000ft

 

[SnoKing]

64mph cruise on at 5000ft

So does it just hunt, or does speed fall off 2-4 mph then shift?

 

[6V92TA]

lock out 6th when towing .

 

[SnoKing]

lock out 6th when towing .

Not with 4.10's unless one wants to tow a 50-55 MPH.

 

[6V92TA]

shoot Snoking, I lock out 6th and I have 410's. you wouldn't believe how happy that engine is running higher rpm while under load. fuel economy is the same and coolant temp is a little lower. counterintuitive but it seems to work that way

 

[Cummins12V98]

lock out 6th when towing .

Why??? I never lock out 6th and I have the AISIN and 4.10's also.

OP I suggest taking it to the Dealer. LEVEL ground towing 35k combined mine never drops a gear. It takes a fairly good grade for it to drop to 5th. It NEVER hunts.

 

[6V92TA]

hey 12V, to answer why? first of all you surely don't have to nor is a it a requirement but I did some serious testing of the situation and found that for the most part running higher rpm in 5th kept my cooling system temps a little lower, my boost pressure a little lower,I got better exhaust braking and I got the same fuel mileage.. on the surface that result is counterintuitive, but I derived that result from more than 1000 miles of testing, some of it bi directional on same route with same conditions before I arrived at that conclusion

 

[Learjet]

64mph cruise on at 5000ft

yep, I have seen that...I think there is glitch or something in the programming...that altitude plus certain speed it will shift back and forth or cycle. Locking out 6th was my solution until I got to a different elevation.

FYI ...I had my Trans flashed to the latest transmission software that was available last summer 2017.

 

[Learjet]

see this thread for some additional info https://www.turbodieselregister.com/threads/weird-cruise-control-issue.260936/

 

[Marion B Butler]

shoot Snoking, I lock out 6th and I have 410's. you wouldn't believe how happy that engine is running higher rpm while under load. fuel economy is the same and coolant temp is a little lower. counterintuitive but it seems to work that way

I agree 100%
Towed two hours today at 6000ft.
64mph, 2100 rpm. Much happier truck.

 

[Cummins12V98]

I have towed at elevation many times. No dropping/hunting gears and no issue with engine or trans temps.

I did tow in 5th with my 11 HO Dually with 3.42's at the same rpm as current 15 DRW.