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4L80 With No TCC Lockup

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Old Jan 16, 2023 | 11:47 AM
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TurboJ4000's Avatar
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From: Detroit
Default 4L80 With No TCC Lockup

Hello all,

I have a problem that I cannot seem to get cleared up and hopefully you all have some ideas on what to try next.

I have a 2001 LQ4 with a cam and 706 heads mated to a 2004 4l80 with a Transgo HD2 kit. I am using the 2001 harness and PCM in a 2004 chassis with a body swapped Jeep Gladiator on top of it. I've been tuning the PCM with HP Tuners but for some reason the converter will not lock. It will shift through the gears like normal all the way from 1 through 4 but wont lock the converter at any time. I haven't had a ton of time driving it because the transmission starts to get warm and I don't want to burn it up.

I have confirmed the resistance across the pins in the plug on the trans and the TCC solenoid is within spec there ~10.6ohms. I confirmed that the TCC solenoid control wire does not have issues from the trans connecter to the PCM connector. With HPTuners I can watch the TCC Brake switch and that is functioning properly and not keeping it locked out either. The fluid level is correct and the fluid is new and not burnt etc. Because it shifts through all the gears I think its getting good power to the solenoid but that and putting a gauge on the test port and confirm the line pressures are all normal is next on my to do list but I'm out of ideas after that.

When I am driving it and I attempt to force the TCC to 100% PWM via HPTuners the TCC apply/engage does not show that it is engaged nor do the RPMs match on the turbine/engine so its not locking. I can't tell if its the tune not telling it to lock or if there is a mechanical issue with the lockup. I have maxed out the misfire tables to prevent that from being an issue but still no go.

Any other ideas on what will keep it from locking? Any tables/issues I don't know about? Or haven't found in my searching.


My next idea is to copy everything transmission related from a 2004 base tune out of the repository and see if that somehow corrects the issue.

Do you guys have any ideas?

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