"05 TC lock up vs Ebrake

[JSchooley]

Pardon my rambling on this. I am still trying to figure out the logic driving the torque converter clutch in my '05 automatic, especially in tow/haul mode. I want to add an exhaust brake such as Pacbrake but am confused about when the TC is/is not locked up and if I need an additional transmission controller.



When going down a long hill with no throttle applied the transmission will go into a retard mode. Is this simply a TC lockup or is it down shifting? In the Tow/haul mode does the TC stay locked up when you back off the throttle?



Is there a place where I can monitor the lockup clutch signal? Given a connector and wire color I can make a monitor that will insure I have a lock up before applying the Ebrake.



Any information will be greatly appreciated.



Thanks much in advance.

 

[Hoefler]

In normal driving mode: the transmission will disengage and go to freewheel at 45 mph, in tow/haul it will stay in down to 35 mph. The torque convert stays locked in until these speeds are reached. The transmission will actually shift down to slow the truck if you are in cruise or on a long down hill. What I find very un-nerving is when driving at low speeds ( lower than 45 ), the transmission will disengage and you can actually increase in speed if you are on a hill!! Around here I drive in tow/haul mode loaded or unloaded to help with engine braking. It has helped with fuel economy as well. The transmission doesn't down shift near as much and it will pull the hills very well in overdrive!

 

[p-Bar]

Beware putting an exhaust brake on a 05 it will void your warranty on the trans, while extensive testing was being done by Cummins they saw that even if a signal was sent to the converter to lock up it still didn't lock up at times. Good luck