P0727 issue

[DIESELMAFIAPER.LB7]

So I'm fighting a truck that keeps kicking this code. Stock trans never been apart. I swapped the sensors out no change. Checked the wires at tcm have continuity through them least the two on the trans I checked didn't check speed sensor on t case but speedo works fine.

Truck drives perfectly fine just kicks a light after a key cycle.

I am watching input sensor speed and turbine speed and turbine lags behind like It should but soon as I give it rpm it goes to zero??

Put it in gear it drops to zero like it should idle it shows 30-50rpm slip.

I replaced the pigtail ends for kicks no changes anyone else fought this before? This is the only code I get and I don't get issues from truck driving goes through gears lock up is good just stumped on this one.

 

[DIESELMAFIAPER.LB7]

If I swap the plugs around I get 0 rpm from input speed and only 300 from turbine speed sensor. So this leaves me to beleive the issue still lies with the turbine speed sensor or wiring even though I have continuity

 

[2004LB7]

From the late Mike L:

"First of all; when you replaced the speed sensors, did you clock them as the factory had them. Installing them any which way does not work sometimes as they are directional ( they sense the pulse from a single point on the sensor ). If you positioned them as factory, then I would take a look at the dimples on the converter and see if you have a damaged one. The dimples act as the exciter for the sensor and one damaged dimple will set the codes you see"

 

[PureHybrid]

So when you drop into gear, it shows zero slip between input speed and turbine speed? In gear the slip should show the same as engine speed until you start moving (assuming there's no clutch slippage)

 

[DIESELMAFIAPER.LB7]

So when you drop into gear, it shows zero slip between input speed and turbine speed? In gear the slip should show the same as engine speed until you start moving (assuming there's no clutch slippage)

It shows 680 rpm slip. When dropped into gear.

In park I can Rev it and it goes from slipping 30-50rpm to matching rpm of the engine.

When I drive it soon as I get moving it matches input rpm as well.

 

[DIESELMAFIAPER.LB7]

They come with the bracket on them so hard to not be right but I can adjsut them and nothing changes

From the late Mike L:

"First of all; when you replaced the speed sensors, did you clock them as the factory had them. Installing them any which way does not work sometimes as they are directional ( they sense the pulse from a single point on the sensor ). If you positioned them as factory, then I would take a look at the dimples on the converter and see if you have a damaged one. The dimples act as the exciter for the sensor and one damaged dimple will set the codes you see"

 

[DIESELMAFIAPER.LB7]

Well had another 04 lb7 here so I swapped tcms and it all works as it should now so tcm was still junk. I had eliminated everything it could be other then that so swapped it and boom it works.

 

[2004LB7]

Double check the pins in the connector both sides, harness and TCM for any that might be loose or not making a good connection. TCM may not be bad unless you've already checked it in another vehicle and got the same code

 

[PureHybrid]

If you have or can get the tools to do a drag test on the pins, that would be helpful

 

[DIESELMAFIAPER.LB7]

I did swapped into the truck I took the good tcm from same code instantly

Double check the pins in the connector both sides, harness and TCM for any that might be loose or not making a good connection. TCM may not be bad unless you've already checked it in another vehicle and got the same code