sallyman1

Does a 48RE torque lock up in overdrive or only when tow haul is pressed (3rd)? how can u tell if your torque locks up? rpms drop? do u want it to lock up when empty or when towing?

Rpainter

it does lock up and if I remember right it should lockup in od at 54 mph When it is locked you get less heat and a little better fuel mileage

ratlratl

In stock configuration, as best I remember, the tranny doesn't go into lock up in first. It does go into LU part-time in 2nd and 3rd. Unlocking before shifts. It immediately goes into lock up once into OD or 4th. IIRC putting it OD off or 3rd at speeds over 45 it will be in LU. Let off the accellerator pedal and once it drops to a certain RPM it comes out of LU. Thus the run away problem going downhill. LU is best described as like a manual truck. It's a direct drive of the motor to the trans. The RPM's will drop slightly. Third feels like it shifts twice. It is better to be in LU as more pulling power is being sent from the motor to the drivetrain. I'm sure others will chime in and fill in the details I've missed here.

Chris

sallyman1

thanks for the info

omaharam

Only one problem with the above info. The TC will only lock in 2nd if the gear selector is in 2nd. If you just leave it in "D", it only locks in 3rd and 4th.