e38 t42 4l80 stuck in limp mode

[PBJ83CAMARO]

I cannot for the life of me figure out what configuration I need to monitor the trans. Stuck in limp mode no codes - harness if from a 2008 express 3500 with 4l80 so should be correct, good power to all correct wires and god ground... as far as I can tell I have the correct OS so no need for segment swap. Checked shift linkage a dozen and a half times and everything on the shifter and trans aligns perfect. When put in reverse first time its all there, put in D nothing, put in 3 goes into gear great ( I'm guessing the trans will actually be in 2nd), go back to reverse and almost nothing there. Can rev RPMs and barely moves.

[PBJ83CAMARO]

I see my attachments are still not coming through.

E38 ECM OS 12617631 -> 1250216
T42 TCM OS 24239921

With data log... i have some channels i think are pertinent.

That's ow it looks on the tune details tabtrans 4L80 T42 TCM.hpl

[Lakegoat]

Do you have a pressure gauge for the trans? Screws into the port above the shift shaft?
If you can pull the pan, look and see if the pressure relief valve has popped out. Sometimes the snap ring doesn't get seated and it blows out---if this is a new build--if not, I wouldn't pull the pan.

[PBJ83CAMARO]

I had the pan off an replaced the harness and filter... didnt see anything out of the norm i suppose. I did add a data log to my previous post right above yours.

[PBJ83CAMARO]

I still dont have an output shaft rpm after replacing with another known good sensor. You can see in the log when im shifting through the gears. Not sure what unkown OB means in the trans shift mode tab.

[Lakegoat]

I had the pan off an replaced the harness and filter... didnt see anything out of the norm i suppose. I did add a data log to my previous post right above yours.

If it was popped out, you would have seen it, LOL. I thought maybe it had been rebuilt.
I don't know what the ob code is either.
Did you add a deep pan? With a stock filter?

[Lakegoat]

I still dont have an output shaft rpm after replacing with another known good sensor. You can see in the log when im shifting through the gears. Not sure what unkown OB means in the trans shift mode tab.

Do you have both sensors hooked up? ISS and VSS?

[PBJ83CAMARO]

Both sensors are hooked up yes. Tried 2 different rear sensors.

[PBJ83CAMARO]

82 monte 5.3 4l80 turbo decap pump gas trans stuff 026.hpt

Here is a copy of the current tune file also.

[Lakegoat]

Open the tune, go to Trans tab---Shift General, Shift pattern type, Pattern A--change to Normal
Go to Shift pressure, Pressure pattern, Pattern A shift--change to Pattern X
If that doesn't help, get a pressure gauge and see if the pump is working.

[Lakegoat]

Check the T42 OS. That might be for a 4L60?
Blindsquirrel on here is good with that stuff.

[Alvin]

I cannot for the life of me figure out what configuration I need to monitor the trans. Stuck in limp mode no codes - harness if from a 2008 express 3500 with 4l80 so should be correct, good power to all correct wires and god ground... as far as I can tell I have the correct OS so no need for segment swap. Checked shift linkage a dozen and a half times and everything on the shifter and trans aligns perfect. When put in reverse first time its all there, put in D nothing, put in 3 goes into gear great ( I'm guessing the trans will actually be in 2nd), go back to reverse and almost nothing there. Can rev RPMs and barely moves.

That sounds like a trans issue. Unplugged it should have reverse and 2nd.

[PBJ83CAMARO]

Open the tune, go to Trans tab---Shift General, Shift pattern type, Pattern A--change to Normal
Go to Shift pressure, Pressure pattern, Pattern A shift--change to Pattern X
If that doesn't help, get a pressure gauge and see if the pump is working.

I did those changes and it didnt help. It feels like it goes into reverse (i feel it engage) but when i press the gas it barely moves....still nothing in OD unless im driving over 35 MPH and i put the shifter in OD then it will go into 4th. See attached log.

[Lakegoat]

Line pressure on your chart doesn't look promising.
Can you get a gauge on there?

[PBJ83CAMARO]

Will do now. Side note, if I just start the car and run the gears it's fine - I feel it go in reverse and moves strong, same with OD. As soon as I press the gas pedal it barely moves in R and OD - put it in 3 and its strong. No codes, reset and way and same scenario all over again. Everything good until I press the pedal.

[PBJ83CAMARO]

At idle 50 psi - shift to reverse drops to 40 then back up to just under 90 then settles at 50. Neutral 50 psi - shift to drive drops to 30 then back up to 50-60 and settles. I hit the throttle and the pressure goes up to 120 but barely any trans.

[PBJ83CAMARO]

put it in third pressure sits at 50 and when i press the gas the gauge moves up and the car moves fine.

[PBJ83CAMARO]

Open the tune, go to Trans tab---Shift General, Shift pattern type, Pattern A--change to Normal
Go to Shift pressure, Pressure pattern, Pattern A shift--change to Pattern X
If that doesn't help, get a pressure gauge and see if the pump is working.

Seems like pump is working. Im not sure what the pressures should be in good working order.

[Lakegoat]

Here you go--

[blindsquirrel]

Nothing in the tune is going to fix a transmission that doesn't default to 2nd (80E) or 3rd (60E) in Drive with the 20-way unplugged.