4T65E-HD TCC issues

[BrianG]

4T65E-HD TCC issues [UPDATED!]

I've been having an issue since getting my C-YA Racing trans built 2 years ago that I'm at a loss trying to resolve. The issue is that the TCC is not releasing when coming to a stop, so the trans is dragging the engine to a halt. I pretty much have to put the car in neutral when coming to a stop to keep the engine running.

* I've flashed all my TCC related settings back to stock and it has not changed the issue at all.
* I had the side cover off last year and checked the wiring harness for any problems which there were none visible.
* I checked yesterday that I have continuity and proper functionality of my brake switch from the firewall through the underhood junction box and to the PCM.

I am working with HPT which unfortunately doesn't show me what the PCM is commanding as far as the TCC is concerned when scanning. Ugh. Drivability is just out the window due to this issue and I'd really like to get it resolved this year, but I don't have it in me to pull the trans again. I'm about out of ideas, but then again, I don't know a whole lot about transs to begin with. Anyone have any insight or suggestions?

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[DarkShadow]

Mine did that in the regal right before i sent it to the Junkyard, good luck

 

[boostedguy05]

stop by on wed. a buddys dad owns the trans shop by thortons. he should be able to track down the problem. he likes side work.

 

[BrianG]

Worked on it some more tonight and found that even after tuning the TCC to not kick in till 255mph (effectively never), the TCC is still locking up as soon as I get to 2nd gear and it's staying on even in first when downshifting to a stop. I'm thinking that the TCC is engaging as soon as the trans goes to 2nd because the shifts to 2nd and 3rd are hard as hell.

 

[RICH17]

Is HPT reading vehicle speeds properly?

 

[02BlueGT]

Like I said tonight, might not be that it is commanding, but there could be a wiring or a physical TCC solenoid issue... They can be bad from brand new

 

[SleeperLS]

The actual solenoid was my guess as well. Good luck.

 

[BrianG]

It's wierd tho because the TCC lets go as soon as I put it into neutral and then back into gear. I was getting a TCC stuck ON MIL last year but have yet to see if it actually registered again this year. I still have another test to run to see if the TCC engages at all while leaving the car in 1st gear. I'm going to check continuity and correct pinout on the trans connector and PCM tonight too. F*ck this car. Seriously.

 

[Turbocharged400sbc]

yay another car im gonna get stuck diagnosing

 

[BrianG]

yay another car im gonna get stuck diagnosing

You've already started!! Love chew!

 

[Turbocharged400sbc]

serves me right id have to diagnose another 1st gen with an l67 swap after i fixed angels car.

im gonna hotwire yer ferd and use it to haul hk's heap out to norwalk

 

[BrianG]

LOL! I would almost toss you the keys if I wasn't gonna be hauling with it that weekend already.

 

[BrianG]

Okay, more info. If I put the shifter down into 1 or 2 it seems like the TCC never engages and I can come to a stop without killing the engine. In D or OD, once I get into 2nd or higher, the TCC stays on until I put it in neutral, and the gear shifts are really hard. The 1-2 shift while in 2 seems to be a lot more "normal" and doesn't kick like a mule. Thinking I'll be pulling the side cover again.

 

[RICH17]

Could it be in the harness? I mean you found alot wrong in the service manuals....

Wanna swap harness'?

 

[RICH17]

Nevermind. Mine doesnt have the blower stuff....yet.....

 

[Turbocharged400sbc]

dont pull the fucking side cover yet dude, diagnose it the right way so you can fix the actual problem and not throw parts at it

 

[BrianG]

dont pull the fucking side cover yet dude, diagnose it the right way so you can fix the actual problem and not throw parts at it

That's what I'm hoping to do. I've got all the manuals, but haven't done everything step by step yet. And I don't have a scantool with the ability to see what the PCM is commanding for TCC or what it reads as the status. Might need some assistance there. I need to see if I can read slip speed with HPT while scanning. I imagine it'll show 0?

I checked continuity from the PCM to the trans harness plug last night on every pin. The pinouts matched the book 100% except IIRC, the "sensor ground" wire didn't show continuity, however the trans temp seems to be reading just fine. iono.

 

[RICH17]

I wonder what will happen now that I found that ground wire not connected.....

 

[BrianG]

I wonder what will happen now that I found that ground wire not connected.....

Probably nothing, but thank you nonetheless. It's been hooked up in the past with the same problem.

 

[Turbocharged400sbc]

iirc there is a seperate ground wire for the pressure manifold switch assembly that tells the pcm which hydraulic circuits have pressure....
yet another thing youd want my snapon fer

 

[BrianG]

Okay, probably the last diagnosis update before a solid answer is found, I rip it open and replace the tcc anyways, or I molotov cocktail the engine bay.

I snipped the TCC wire going into the trans to see if it reacted any differently and it drove exactly the same. Leaving it in 2 thru 2nd to start and then shifting to D kicks really hard, but the 1-2 shift feels perfectly normal.

 

[BrianG]

UPDATE: After over 2 years of dealing with this since day 1 after it was built, I have finally solved the problem. Just like I suspected since I got it, the TCC PWM solenoid was bad. I replaced it over the weekend and drove it last night and it was spectacular. Without even a trans tune, it shifted crisp and quick, but not brain jarring like it was previously. The car doesn't constantly engine brake and finally comes to a stop without killing the engine. NO MORE MANUAL SHIFTING!!!! I'm so friggin happy right now and I can't wait to go racing! Problem solved!! FUCK YOU C-YA RACING FOR NOT LISTENING TO ME!

 

[Turbocharged400sbc]

your still slow