2018 Aisin Torque Converter Lockup Switch?

[AH64ID]

All of my Aisin have locked up in 4wl, once it goes into 2nd gear it locks, exhaust brake works ( exhaust brake will not work, unless the convertor is locked ), and you can not engage tow haul in 4wl.
On another note, when was the last time you changed the fluid and filter? Fluid is supposed to be changed every 30,000 miles and filter every 60,000 miles

Even in high range they don’t lock in 2nd as soon as it shifts into 2nd, there is a minimum speed for that to happen. It was ~20 mph with both 3.42’s and 3.73’s, which means it was tied to mph and not rpms.

I monitored converter lock with a CTS2/CTS3 on both the 2018 and 2022, the Aisin never locked in low range at a lower speed than high range. Same on dads 2017 and 2022.

They 100% should lock up sooner in 4-Low but some engineer had a better idea I guess.

 

[getpower1]

All of my Aisin have locked up in 4wl, once it goes into 2nd gear it locks, exhaust brake works ( exhaust brake will not work, unless the convertor is locked ), and you can not engage tow haul in 4wl.
On another note, when was the last time you changed the fluid and filter? Fluid is supposed to be changed every 30,000 miles and filter every 60,000 miles

Truck has 44,000 on it. I did just do a drain and fill after the first incident. But because of age I should probably drop the pan and replace the filter and fluid. I’ll fully admit that.

 

[Topzide]

That's way past the schedule for a drain. Transmissions are very finicky about fluid changes! To many components in a trans to not follow the recommendations on fluid change.

The following is a cautionary tale to not do trans flushes:
I found that "flushing" a trans (not my trucks), isn't a good way to service a trans. It killed a trans at 60k! What happens with a flush is, it pushes fluid backward through trans. When that happens, anything that was caught in the filter is now pushed though the trans and not always filtered back out! This allows that debris to cause more damage! It's just a money maker for a service department!

 

[Cummins12V98]

"Fluid Exchange" is where it'a at but I have not figured out a way to do so with the AISIN. 68RFE and 47/48 trans are very easy to do so.