2004 6.0 4l80e we are having problems with the lockup and cruise on the truck. Using the snap on brick we can command lock up and it works fine. These are the values the scanner shows: tcc open/short- yes, all other shorts- no, brake switch is working (can see on scanner), all temps are up, speed sensors are fine and working smooth... ecm will not command lockup.

Anybody have any tips?? Thanks

 

Is it bone stock?
lil more info would help

So it shifts thru the gears just fine?

 

Misfires will cause that. Even if it is not enough to set a code for them.

 

Bone stock, 245k miles. Lol. There are stored codes for misfires, but nothing active... Shifts perfectly thru the gears, just never locks.

 

Did you try clearing the stored codes to see if it locked???

Did you verify your getting voltage at the TCC???

Did you verify the TCC is actually good???

 

We verified power and ground to the tcc.. Took it out and made sure the oring was good and the screen wasnt plugged. Everything looks perfect- it also Ohm checks good. We can engage it anytime we want with the scanner and it works great. The problem seems to be on the computer side. I will clear all the codes and go from there. Any more suggestions? Thanks for the help guys

 

Have all the conditions been met? PCM wont command lockup if all the conditions are not met.

 

Hmm- Explain please... Im not sure, would this be on the scanner? Forgive me if I sound like I dont know what Im doing.. The mechanic is a tranny guy and isnt too familiar with the ecm troubleshooting.

 

I'll post the worksheet around lunch time.

 

Thanks