My new (to me) truck has the stock 48LE transmission. This is a 4 speed auto, 4th being a .68 O/D. Correct?

No box or tuners have ever been used on it. And probably won't as long as I own it.

There's three settings for the transmission. Default is normal shifting/operation. I'm guessing this is designed for smooth shifting and economy?

Push the button once and it goes to tow/haul mode. It feels like shifts are a little later, and a little firmer. OD is not locked out. I'm guessing this raises the pressure in the trans? Upshifting to O/D while towing is not an issue. But I'll need to be gentle with the go pedal to avoid harsh banging shifts.

Push the button again, and your get O/D Off. The first three gears shift like normal. But (obviously), it never upshifts to 4th. Good for around town driving or to generate heat better on a cold morning.

I have not recieved my factory service manual yet, so I can't just look it up. I'm thinking the default setting is easier on the trans when not towing. Does all this sound right? My main goal with this truck is longevity and durability.

 

Hi .. I will try to help you understand what is going on with your trans

Frist , in normal the trans shifts 1,2,3,4 ,OD

tow /haul,,, it shifts 1,2,3 then it goes in lock up TQ then 4th
from what i understand this helps when towing a load as it goes in OD so the TQ will not be slipping plus it allso keeps the TQ locked up in down shifting to help brake the truck when slowing down, it unlocks some where in 3th or when it down shifts in 2nd

and OD off,, just like it says shift 1,2,3,4 no OD

I know some that keeps it in too tow haul all the time , it will not hurt the trans , I am not to sure if it raises the line PSI in the trans,

Hope this helps some ,, I sure there is a lot more to is than i know , and other can tell you
take care
Jman

 

It's a 5 speed auto? I thought it was a 4 speed, with 4th as an overdrive gear.

 

Yes. It is a 4 speed

 

yes 4 speeds with a lock up TQ

 

Its NOT 1,2,3,4,OD. Its 1,2,3,OD lockup is not another gear.

 

That's what I thought it was. Thanx.

So, what does the tow/haul mode actually do?

 

TH essentially gives a more aggressive lockup and shift program. It will lock the TC sooner in drive and OD and under certain conditions in 2nd. Tends to upshift to drive and OD sooner also to minimize the time in fluid coupling and non productive gears.

It will tend to bang the shifts empty but they smooth out a lot when loaded. In reality the firmer it shifts the better it is. A sloppy shift and lockup is slipping the clutches a bit to achieve a smooth engagment. It just accelerates the wear if it does it a lot with too much power or load.

I absolutel hate the non-TH shift and lockup protocols and run in TH almost all the time.

 

It is a 48RE. Od is .69.
R is rear wheel drive, L is longitudinal.

 

It is a 48RE. Od is .69.
R is rear wheel drive, L is longitudinal.