E40/T42 no ISS Trans tune.

[jhbau1000]

I have the transmission shifting and TCC locking up fine now. Its just when you log the TCC records a slip. The TCM or ECM which ever one that does the calculation seem to still be looking for the ISS sensor. So the ISS sensor is coming in as zero. So it is calculating the TCC as (ISS-RPM) = TCC slip. With the ISS disabled it should be (OSS-RPM)*Gear Ratio = TCC Slip.

I do not have any other T42 files and yes this T42 file has been changed a few times. I wish I knew which 13-pin 4L60/65 calibration file I needed probably should have researched it more and that is on me. For now my fix is to disable P0741 & P0894 and let it ride.

[garkhul]

Im currently stuck in the same boat. I can disable iss under trans diag but it still throws p0741, i tried to disable the dtc for it and it pretty much bricked the trans. it wouldnt do anything. have a 13pin 4l60 with a 15 pin t42 tcm

[jhbau1000]

I'm still working on this garkhul. I have been in contact with HPTuners it appears that turning off the ISS does nothing for changing the way the TCM\ECM calculates TCC slip. Now it did take my transmission shop 4 times to get the TCC to not show a slip using (OSS-RPM)*Gear Ratio = TCC Slip in VCM Scanner. Also on the 3rd time the transmission went in, it stopped pulling altogether. Turned out to be the pump vanes broke and it was no longer pumping fluid.

Now I have put about 1,000 miles on transmission with the P0741 turned off. It seems that when you put it in reverse it takes it a few seconds to engage. I stopped driving it, now I'm waiting to after the holidays to change out the transmission filter and fluid.

I have a 2 more Tune files that is supposed to work with these 13 pin transmission, but I have not tried them. It cost 2 credits each to use the files and you only need the TCM part of file. I'm have been reluctant to try it, because I have bought 2 other files that I was told would work but did not. I will post the files here if you want to take a shot at them. If you do try one of these files let me know please. It sure would be nice to narrow this done so others don't waist there time and money on files that don't work.

[TransGo Robert]

I'm still working on this garkhul. I have been in contact with HPTuners it appears that turning off the ISS does nothing for changing the way the TCM\ECM calculates TCC slip. Now it did take my transmission shop 4 times to get the TCC to not show a slip using (OSS-RPM)*Gear Ratio = TCC Slip in VCM Scanner. Also on the 3rd time the transmission went in, it stopped pulling altogether. Turned out to be the pump vanes broke and it was no longer pumping fluid.

Now I have put about 1,000 miles on transmission with the P0741 turned off. It seems that when you put it in reverse it takes it a few seconds to engage. I stopped driving it, now I'm waiting to after the holidays to change out the transmission filter and fluid.

I have a 2 more Tune files that is supposed to work with these 13 pin transmission, but I have not tried them. It cost 2 credits each to use the files and you only need the TCM part of file. I'm have been reluctant to try it, because I have bought 2 other files that I was told would work but did not. I will post the files here if you want to take a shot at them. If you do try one of these files let me know please. It sure would be nice to narrow this done so others don't waist there time and money on files that don't work.

Fluid and filter change is maintenance, it is not going to fix a problem. Plust if the pump broke 1000 miles ago then the fluid is new in there, no need to service it. Be sure that you have the right clearance 3/8" between the converter and flexplate or else the pump will break again. I would ask the builder to check it to see what is up with the reverse delay if it was me. As for the tunes I can't help with that, but last time you had posted a log everything was working fine it was just the computer that was thinking it was slipping. If you have the P0714 turned off all should be good now unless I am missing something.

[jhbau1000]

Everything seems to be working fine except every now and again i have the reverse delay. It acts like it is low on trans fluid. I have to give it a little gas for it to grab reverse.

[TransGo Robert]

Everything seems to be working fine except every now and again i have the reverse delay. It acts like it is low on trans fluid. I have to give it a little gas for it to grab reverse.

Add a quart and see if it makes any difference. It might be low or the filter might be cracked, if that's the case it would do it only when cold. But if that's the problem it would to it both forward and reverse so I really doubt it is that.

[jhbau1000]

Ok, I finally changed the fluid and filter in the 4l60E. I still have the delay when going into gear. It does it both ways forward and reverse. The RPM's have to be 1250 for it to engage. Right now I'm looking for anyone that knows what is the best T42 Operating System for a 4l60E NON ISS 13 wire. I'm running OP-24235341 and have to disable P0741 for it to lockup TCC. I have 2 T42 file for a GTO with T42 OP-24231674 and one with OP-24236195. Does anyone know the difference.

[TransGo Robert]

Ok, I finally changed the fluid and filter in the 4l60E. I still have the delay when going into gear. It does it both ways forward and reverse. The RPM's have to be 1250 for it to engage. Right now I'm looking for anyone that knows what is the best T42 Operating System for a 4l60E NON ISS 13 wire. I'm running OP-24235341 and have to disable P0741 for it to lockup TCC. I have 2 T42 file for a GTO with T42 OP-24231674 and one with OP-24236195. Does anyone know the difference.

Did you ever try over filling it like I had suggested? Also when you had the pan down, did you check to makes sure your dipstick full hot mark was at or just above the pan rail? The computer is not going to cause what you have, this is strictly an internal issue.

[jhbau1000]

Yes the dipstick looks like it should be reading right. But when you pull out dipstick it shows fluid 4 inches up the stick. I dropped pan and then put in 5 qt. After driving it I added another 1 1/2 qts to see if it would help. Setting in driveway shifting it I thought yes its shifting now, but after backing out of driveway and putting it in drive it is still taking 1250 RPM to engage. With the dipstick reading so high I'm afraid of over filling it. LOL Right now I know it has 6 1/2 qts in it after change. Tomorrow I will check it again and see if it needs more.

[TransGo Robert]

Yes the dipstick looks like it should be reading right. But when you pull out dipstick it shows fluid 4 inches up the stick.

Was that with the engine running or engine off?

[jhbau1000]

Running.

[TransGo Robert]

Running.

OK then unless it is the wrong stick completely, you have a pump issue unfortunately. :-(

[jhbau1000]

Took truck for a drive today and now 3rd and 4th gear is gone. Had to put it in 2nd and drive 25 mph to get home.

[TheMechanic]

Saw this coming in post 63 unfortunately.

[DigEm355]

I have exactly this issue. Can someone tell me which transmission I need to get that the t42 will work with, one with the 15 wire and the iss?

[jhbau1000]

DigEm355 - Need more information on what you have and what you need.

[DigEm355]

I have exactly the same issue you have. I am not driving it at the time. 2005 Colorado, E40 and T42. I want to know if anyone knew what transmission I can buy that will work, like with the 15 pin and has the iss and will stop the issue. Instead of trying to program what I have and ending up with a bad transmission.

[jhbau1000]

Sorry DigEm355, did not see your post. Did you find a transmission that worked for you? Is your Colorado 4x4? I think any 4l60e from a v8 will work on the bell-housing side. If its 4x4, I don't know if the output shaft is the same. Someone on here should know if it's the same. I do know that a full size truck the transfer case is on drivers side and on the Colorado it is on the passengers side. But it does not matter if you use the Colorado or a donor transmission you will still need a T42 program that works with the e40. Finding the best T42 program is where I'm stuck right now.

[Vette496]

Can anyone confirm or deny that the calibrations shared here are working files. I have a conversion 2004 colorado with a weird issue. I bought a harness and the TCM from current performance a while back. I have been in contact with them about the problem and they suggested moving it over to a 2006 gto calibration. The problem that occurs is that everything works perfectly for an extended period of time then at random it will command 3rd gear on the highway. When it commands third it will have no engine braking and shifts late and hard. After driving a short time maybe a mile or two it all goes back to normal and everything works properly. This is the second trans this truck has had put into it with the same symptom. The transmission is not being hurt in any way and has a clean pan if removed. Any help confirming that these calibrations are legit before installing would be great.

Thanks!!!

[Alvin]

Scan for codes when that happens. That sounds to me like a communication code is popping up.