2018 Aisin Torque Converter Lockup Switch?

[getpower1]

Hello,

I used to be a member here but I guess I've been gone long enough for my account to be deleted.

I have a 2018 3500 SRW 4x4 with the Aisin. I tow a three axle fifth wheel with it (not fully loaded, but still heavy), and I live at the top of a pretty steep hill. When I come home from camping I have a pretty good maybe 1/4-mile climb and the truck doesn't get out of first gear. This hasn't been a problem in the past, but I have recently upped my tire size to 285/75/18's from the stock size. Truck only has 44,000 miles on it and i bought it new.

With the new tires, pulling the trailer up the hill the transmission temperature skyrockets. Everything is fine and normal the rest of the trip as well as empty. Trans doesn't get over 163 degrees. It also could have done it before the tires and I just never noticed it.

But when I stop at the stop sign at the bottom of the hill and go for it, the temps get out of control pretty quickly.

I'm coming to the realization with the research that I have done that the torque converter doesn't lock in first gear. Other than going back down to the stock tire size, is there anything you can think of that would make the hill climb easier on my equipment? Cause I'm sure that going back down the 1.2 inch difference in tires won't fix a problem that I probably didn't notice till now.

I have tried climbing the hill in 4 Low, that still made the temps climb but didn't set off any nanny lights. Didn't make enough of a difference to do it again. I have done a drain and fill with new fluid also. I'm pretty sure its not fluid related. I have also called a tuning company and they said they don't mess with the torque converter, just the shifting.

Is there a way to get first gear to lock up? A switch maybe like they used to do with the old 48RE transmissions? Just for the one instance that I run into getting up the hill? Realistically, I can change my route, but I prefer to back in the direction that coming up the hill gets me into.

Any comments are appreciated. I'm very mechanically inclined and can answer more questions on the issue if I have forgotten anything. But I am not great with maintenance. Oil gets changed every 5000. Fuel filters every 10,000. But if I'm being honest I should probably look at some of the other things that are recommended.

I can't be the only person where first gear not locking up has been an issue.

Thanks.

 

[petersonj]

pulling the trailer up the hill the transmission temperature skyrockets

Trans doesn't get over 163 degrees.

What temperature is "sky rockets"?

- John

 

[lpennock]

163 is not hot. Mine runs 160-165 most of the time. So what do you mean by "sky rockets".

 

[getpower1]

Good point. Should have mentioned. I saw over 180 on the dash quickly and wherever the temp reads for the torque converter made the red lights come on on the dash, and the truck started dinging at me, and started shifting clunkily trying to get out of first or something…maybe it was backing itself off…

Once at the house and parked everything cooled right down quick and truck has been perfectly fine since. This was the first time. Second time when I tired it in 4 Low the temps started climbing fast again, though I didn’t see higher than 180 and no lights on the dash, no warning noises, but the truck didn’t feel happy.

 

[petersonj]

I would try again in 4wd low range and select 2nd gear manually. The converter should lock up and stay locked up. If it does, your issue is resolved. You may even be able to use 3rd gear manually.

- John

 

[AH64ID]

Good point. Should have mentioned. I saw over 180 on the dash quickly and wherever the temp reads for the torque converter made the red lights come on on the dash, and the truck started dinging at me, and started shifting clunkily trying to get out of first or something…maybe it was backing itself off…

Once at the house and parked everything cooled right down quick and truck has been perfectly fine since. This was the first time. Second time when I tired it in 4 Low the temps started climbing fast again, though I didn’t see higher than 180 and no lights on the dash, no warning noises, but the truck didn’t feel happy.

Absolutely nothing wrong with 180°-200°, keep doing what you’re doing in 4-Lo. You won’t see a light until well over 200°, heck the fan doesn’t even kick on for pan or TC outlet temps until well over 200°, and closer to 300°.

I will say that I’ve done lots of slow speed towing and decent weight on multiple mile long steep grades with my Aisins and never seen a dash light ding, even with pan temps around 200° and using 2nd gear under 20 mph. In 1st gear under 20 mph the TQ temps and pan temps are lower. Make sure you’re locked in 1st. Without locking the truck in 1st it would easily shift to 2nd way too early, even with the 3.42’s the 2018 had.

I would try again in 4wd low range and select 2nd gear manually. The converter should lock up and stay locked up. If it does, your issue is resolved. You may even be able to use 3rd gear manually.

- John

Lockup won’t happen in 4-Lo any slower than high range. I’ve tried many times and even had the BD 2-Lo kit. Lockup is based on vehicle speed unfortunately, at least with the AS69RC.

 

[petersonj]

Lockup won’t happen in 4-Lo any slower than high range.

Thanks for the correction.

- John

 

[Ozymandias]

180 can run all day long just fine, start to really worry at 230.
The Trans is built for that and today fluids are far from the stuff we had 30 years ago and older.
Fact - You don't do any harm to it below 220.

 

[Hoefler]

I had 285* crawling the Bighorn during road construction. No problem, fluid never burnt, and never an issue coming home with it.

 

[Grumpy8811]

a momentary climb of transmission temperature is not going to hurt the transmission.
it is constant hi temps, say over 220F that degrade the fluid.
you didn't say how hot it was but a hill climb in low shouldn't hurt it

 

[getpower1]

a momentary climb of transmission temperature is not going to hurt the transmission.
it is constant hi temps, say over 220F that degrade the fluid.
you didn't say how hot it was but a hill climb in low shouldn't hurt it

I mentioned that I saw over 180 on the dash, which can’t be accurate to the actual temperature because it got hot enough for the truck to throw a warning light and back off a bit and the transmission was shuttering and got clunky.

I wish I could figure out what percentage grade the hill is to accurately tell everyone what I was dealing with. It’s steep steep, and my best educated guess would be about a 1/4 mile long. Can verify with a map app I guess.

edit: map app says the climb is 0.3 of a mile. Still working on the grade. Maybe the off-road pages on my bronco dash later today.

 

[AH64ID]

I mentioned that I saw over 180 on the dash, which can’t be accurate to the actual temperature because it got hot enough for the truck to throw a warning light and back off a bit and the transmission was shuttering and got clunky.

I wish I could figure out what percentage grade the hill is to accurately tell everyone what I was dealing with. It’s steep steep, and my best educated guess would be about a 1/4 mile long. Can verify with a map app I guess.

edit: map app says the climb is 0.3 of a mile. Still working on the grade. Maybe the off-road pages on my bronco dash later today.

The dash is accurate for pan temps. The truck also monitors torque converter outlet temps. With pan temps of 180° and TQ converter temps high enough for a warning light that sounds like second gear was being used, 1st doesn’t create near the heat that 2nd does at the same speed. I’ve not had that big of a temp delta with 1st gear.

If you want to know the grade create a route on MapMyRun.com.

Is it paved or dirt?

4-Lo or 2-Lo (BD kit) is your best bet. There are a few short grades where I hunt that I need to use low range for, it’s very effective at keeping unlocked temps in check.

 

[Ozymandias]

The dash is accurate for pan temps. The truck also monitors torque converter outlet temps. With pan temps of 180° and TQ converter temps high enough for a warning light that sounds like second gear was being used, 1st doesn’t create near the heat that 2nd does at the same speed. I’ve not had that big of a temp delta with 1st gear.

If you want to know the grade create a route on MapMyRun.com.

Is it paved or dirt?

4-Lo or 2-Lo (BD kit) is your best bet. There are a few short grades where I hunt that I need to use low range for, it’s very effective at keeping unlocked temps in check.

Depending on the gear it should also lock up in Low range at a significantly lower speed.
I believe my classic locks at 12mph in 2nd Low and keeps it down to 8mph.
I hope the new ones can do that to.

 

[AH64ID]

Depending on the gear it should also lock up in Low range at a significantly lower speed.
I believe my classic locks at 12mph in 2nd Low and keeps it down to 8mph.
I hope the new ones can do that to.

They do not.

 

[Ozymandias]

...what a step backwards in technology.

Is this in all 4th Gen Truck, or only the Aisin?

 

[AH64ID]

...what a step backwards in technology.

Is this in all 4th Gen Truck, or only the Aisin?

Not sure, maybe I’ll see how my 66RFE acts in low.

 

[lpennock]

@AH64ID Stupid question, Could his Transmission coolant thermostat be bad?

 

[getpower1]

The dash is accurate for pan temps. The truck also monitors torque converter outlet temps. With pan temps of 180° and TQ converter temps high enough for a warning light that sounds like second gear was being used, 1st doesn’t create near the heat that 2nd does at the same speed. I’ve not had that big of a temp delta with 1st gear.

If you want to know the grade create a route on MapMyRun.com.

Is it paved or dirt?

4-Lo or 2-Lo (BD kit) is your best bet. There are a few short grades where I hunt that I need to use low range for, it’s very effective at keeping unlocked temps in check.

It definitely couldn’t shift out of first. There’s a stop sign at the bottom of the hill and it’s on a grade itself. I always tried to just ease the truck up the hill.

I’ve looked into the 2lo kit and always thought I’d put it in, but it’s not as inexpensive as I thought it would be when I went to look it up.

 

[AH64ID]

It definitely couldn’t shift out of first. There’s a stop sign at the bottom of the hill and it’s on a grade itself. I always tried to just ease the truck up the hill.

I’ve looked into the 2lo kit and always thought I’d put it in, but it’s not as inexpensive as I thought it would be when I went to look it up.

You'd be surprised how easily and quickly the truck will shift out of first, even in the scenario you mentioned. If you didn't have it locked into 1st with ERS I wouldn't be shocked at all if it grabbed 2nd gear. With the TQ converter slip the rpms may not be that different.

Watch Amazon for a 2-Lo kit. I got mine used-like new for $93.

 

[Hoefler]

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