TCC Lockup

[OxcartA12]

Working with Terminator X Max with FW 1.0.130 (1001300) and 4L70E (GMPP #19368613). Driving vehicle with steady state throttle in 4th gear. I noticed when TCC is commanded to lockup, it's actually unlocking. I verified +12V when brake depressed as noted in instructions. If I keep MPH and steady throttle, but squeeze into brake it locks the TCC. I believe OEM is +12V applied all the time with brake depression opening circuit, but the Holley manual states the opposite. Did I miss something or an EFI software revision? Thanks in advance.

[andrewb70]

There are RPM parameters for TCC. Are you sure you aren't crossing those RPM thresholds? You should also verify again that the brake switch is not sending 12 volts when the brake pedal is not pressed. Andrew

[OxcartA12]

Point taken and I verified brake pedal voltage conditions off = 0 depressed = +12V. I can watch the commanded lockup on the little screen and they function opposite of indicated, very strange.
The TCC RPM Lock/Unlock parameters seem normal as far as above & below each other. I don't have an interface cable right now, so just looking at functions on the included screen. I can literally steady state this car and Lock/Unlock the TCC with brake pedal input, but opposite of what it's supposed to be depress brake = lock release back off and it unlocks.

[81 TransAm]

Is the relay wired correctly?

[OxcartA12]

@81TransAm: If you're referring to the transmission harness relay, yes, it appears to be triggering correctly. I assume I wouldn't have any shifting at all if this did not power up, correct? Is there supposed to be another relay in the circuit as well?

[81 TransAm]

My mistake, I missed that you're using a 4L70E. Are you using the Holley transmission harness? If you cut the wire going to the brake circuit and setup your TCC to unlock below a certain speed & RPM, what happens?

[OxcartA12]

So driving up through the gears into 4th with light throttle, everything is fine 1-4. It's not possible to tell if it's locked at this point (TCC duty cycle 0% and lockup status OFF as indicated on screen), but when I reach my speed/RPM/throttle flags and it indicates 100% duty cycle and lockup status ON, it actually unlocks and the RPM flairs up as expected. The pic on the right is when it unlocks and RPM flairs, it doesn't make sense. I can slow down OK without it stalling or appearing to stay locked up, so that seems to work OK with the correct speed/RPM settings. This is with brake pedal circuit unhooked.

[andrewb70]

I recall something in Holley training about the 4L70E specifically. Depending on the year and a certain pin being present in the transmission main harness connector, it can't be used with the Holley EFI. I wish I could recall more details, but you may want to do a little research about this. If you look in the Dominator section of the Holley website, they do list a 4L70E specific harness. I'm not saying this is your issue, but it's worth doublechecking. Andrew

[OxcartA12]

Oh, good info thank you. I'm going to have to deep dive on the research and also get a lock on what year this transmission is. It's not my car, so somewhat limited information.

[Danny Cabral]

https://forums.holley.com/showthread...Control-Issues (Related Forum Thread)
https://forums.holley.com/showthread...-Max-amp-4L70E (Related Forum Thread)

[OxcartA12]

Thank you Danny, as usual! I guess my search wording needs help LOL!
The "control issues" thread looks more recent, so I'll start there.

[OxcartA12]

So here's the latest with the TCC and my issue. I borrowed a Holley specific 4L70E harness and quickly connected it/powered it accordingly and plugged it into the transmission to test. It wouldn't control the transmission properly, actually not even shifting out of 1st sometimes. This was somewhat expected as the connector on the transmission was black in color (not the blue of 2009+) and after obtaining the model number off the UPC looks to be the GM crate version of the pre 2009 4L70E. I borrowed another 4L60/65/early 70/80/85 Holley harness thinking it may have been a wiring issue, with the exact same results as the original harness. It shifts 1-4 as programmed then on indicated and commanded lock up actually Unlocks. I looked at the ALLDATA schematic for the 4L60/70 and all the Holley harnesses seem to have pin T & U populated which is respectively the TCC solenoid valve (T) and the TCC PWM solenoid valve (U). I’m stumped, but I'm beginning to think it's in the EFI software somehow as when I depress the brake after it unlocks (still keeping my foot steady on the throttle like a brake torque) it will lockup the converter! Any ideas welcome, this is a head scratcher. Keep in mind this is a program generated by the Wizard and those applicable selections so a pretty basic file just to verify function. Anyone interested, here's a quick video link:
https://youtu.be/Uyt2yY2uSEA

[Gaz64]

Your video sounds like the TCC is locked up through all gears to 4th, then it UNLOCKS at the 25 second point, hence the large RPM increase, which occurs when you depress the brake pedal. Gary

[OxcartA12]

I think I just let off and did a coast down to see if the lockup status would change with just the minimum RPM/speed flags, no brake applied. Looking at the minimum gear to lock, it's set at 4th so I can assume it's locked as it shifts into 4. But then again It isn't acting right so who knowns. LOL!

[Gaz64]

Oh sorry, you're applying the brake pedal slightly, and at the 25 second point, you have released the pedal, and the convertor unlocks?