Whats wrong with my 4L80e :(
Thread Starter
Staging Lane
Joined: May 2014
Posts: 80
Likes: 1
Whats wrong with my 4L80e :( Hey everyone,
I need some help diagnosing an issue. I have a 2005 4L80e with a CK Performance D3 trans brake. Everything worked fine last year but I had an issue at the end of the year where the stock P01 computer locked up the converter at WOT and burnt up the lockup clutch and clogged the trans and lost pressure. I have a standalone ECU and was using the stock computer only to control the trans.
This winter I sent the converter back to yank, they pulled it apart and cleaned everything and replaced the clutch disc. My local transmission shop that did the initial build and installation of the trans brake went through and rebuilt the trans. I changed out the stock computer with a standalone microsquirt transmission controller to pair with the ECU which is a megasquirt MS3x.
I got it back together and reverse works fine (I need to enable the transbrake for it to work which is normal) but the transbrake does not work in any foward gear and the transmission feels like it is not starting off in 1st. The transmission controller says its in 1st but it requires more effort than usual to get it to move forward.I have a test mode on the transmission controller and I can manually command each gear. The 2 shift solenoids are acting as they should according to the ATSG manual.
The manifold pressure switch is also working and I verified from Park to 1st.
I talked to the transmission shop and he pulled it apart to look everything over and he said everything looks normal and air checking the clutches everything performed like it should.
I put it back in and I am having the same issues.
So there are 2 issues.
The first being that the trans brake does not work in any forward gear. The vehicle just creeps forward. The transmission shop pressure tested the solenoid when they had it apart and they said it held air pressure fine.
The second issue is that it feels like its not starting off in 1st. Everything electrically and according to the controller says its in 1st gear. Almost like something is binding possibly...
I thought it may be the wiring that controls the transbrake since there is a SSR that tied into my ECU and then a branch off of that that goes to a diode and my reverse lights so I wired a separate relay off of a switch inside to rule that setup out and I have the same results.
Trans pressure is around 170-190psi.
Any ideas what I could be missing here?
Thank you for your help and assistance!
I need some help diagnosing an issue. I have a 2005 4L80e with a CK Performance D3 trans brake. Everything worked fine last year but I had an issue at the end of the year where the stock P01 computer locked up the converter at WOT and burnt up the lockup clutch and clogged the trans and lost pressure. I have a standalone ECU and was using the stock computer only to control the trans.
This winter I sent the converter back to yank, they pulled it apart and cleaned everything and replaced the clutch disc. My local transmission shop that did the initial build and installation of the trans brake went through and rebuilt the trans. I changed out the stock computer with a standalone microsquirt transmission controller to pair with the ECU which is a megasquirt MS3x.
I got it back together and reverse works fine (I need to enable the transbrake for it to work which is normal) but the transbrake does not work in any foward gear and the transmission feels like it is not starting off in 1st. The transmission controller says its in 1st but it requires more effort than usual to get it to move forward.I have a test mode on the transmission controller and I can manually command each gear. The 2 shift solenoids are acting as they should according to the ATSG manual.
The manifold pressure switch is also working and I verified from Park to 1st.
I talked to the transmission shop and he pulled it apart to look everything over and he said everything looks normal and air checking the clutches everything performed like it should.
I put it back in and I am having the same issues.
So there are 2 issues.
The first being that the trans brake does not work in any forward gear. The vehicle just creeps forward. The transmission shop pressure tested the solenoid when they had it apart and they said it held air pressure fine.
The second issue is that it feels like its not starting off in 1st. Everything electrically and according to the controller says its in 1st gear. Almost like something is binding possibly...
I thought it may be the wiring that controls the transbrake since there is a SSR that tied into my ECU and then a branch off of that that goes to a diode and my reverse lights so I wired a separate relay off of a switch inside to rule that setup out and I have the same results.
Trans pressure is around 170-190psi.
Any ideas what I could be missing here?
Thank you for your help and assistance!
