P59 TCC Lockup in 1st and 2nd gear??

[5.3LS10]

Hey Everyone,

I originally posted this in the engine section and just realized that it probably should have been in the transmission section.

I have a P59 from a 2004 Silverado that I swapped into a 1965 Buick Special. Engine, trans, ECU, and harness all came from the donor vehicle.

I am having an issue where the computer is locking up the converter very quickly in 1st gear and does not unlock the converter until you are under 4-5 mph.

Technically there is no option for 1st gear lockup in the table and 2nd gear is set to 256mph so it should never lockup unless it hits 3rd gear.

I have verified that the 12v brake signal goes to Blue pin 33 and there is 12v while driving around and when the brake is applied it goes to 0v.

Speedo in VCM scanner reads correctly.

Any idea what would be causing these issues with the lockup? You can see in the attached data log that the TCC Applied goes to yes while in 1st gear.

Let me know if you have any questions.

Thanks!

[5.3LS10]

bump anyone?

Would you all agree that what I am seeing is not normal and needs further investigation?

I think I have another ECU that is already licensed that I can try. Just want to make sure I am not going down a rabbit hole and that there is definitely some issue here.

Thanks!

[bmac2368]

Boy I just jumped on here and am having the same issue, 2003 Silverado.

A few months ago i threw a 2400 stall in and it worked as it should.

Last week I threw a cam in and now it wont unlock till stopped, it even stalled me out once...

I haven't changed anything in the trans tune so not sure whats going on either?

[bmac2368]

I had a spare pcm that I just tried, with stock tune and same problem. PCM is outputting pwm and locking up the tcc. Just wanted to update my experience so far. Any luck on your end 5.3LS10?

[5.3LS10]

I had a spare pcm that I just tried, with stock tune and same problem. PCM is outputting pwm and locking up the tcc. Just wanted to update my experience so far. Any luck on your end 5.3LS10?

Still having the same issue but I have not had any time to work on the issue.

Been very cold where I live and they salt the roads so project cars go away.

[Just Chuck]

Pressure has to be applied to unlock the converter. Make sure you don't have a kink in a cooler line or cooler line that too small/restrictive.