6L80 transmission rebuild, relearn, & TCC wiring
 

Hey guys
I rebuilt the 2011 6L80 and reinstalled it into my sons truck and was told to re learn the transmission through hp tuners. When I do it, it asked me to apply the brake. When I did I got nothing and the relearn aborts.
So I guess I have a TCC wiring issue.
I have wired it to 12v brake applied, ground when applied and even installed a 1k resister on the ground wire through a relay.
No matter what I did the message asked me to apply brake and then it would abort.
The truck does not move in drive or reverse.

Anyone had this problem? Can anyone help?

Re: 6L80 transmission rebuild, relearn, & TCC wiring
 

You do not need to learn. Make sure your tcm os matches your ecm. Sounds like they are mismatched.

Re: 6L80 transmission rebuild, relearn, & TCC wiring
 

Thanks for the post. I talked to Mike at century transmission. He said that you don’t have to do a relearn. Just be careful and drive normal. After a few drives it will adjust.

I did find out that my truck will see a brake Applied when the truck is off with key on. But when I start it it stays brake released and won’t change.

Re: 6L80 transmission rebuild, relearn, & TCC wiring
 

The tcm sees 3 brake signals. 2 from the bcm and one from the ecm. The only 1 of concern is from the ecu. The ecu will need 12 volts with brakes applied. This is critical. If your trans does not shift or go in gear you have a transmssion issue. When you have a mismatch it will stay in first gear

Re: 6L80 transmission rebuild, relearn, & TCC wiring
 

The trans is working great. My question now is th brake switch applied yes/no. Like I said in the earlier post I see it working line it is supposed to with the engine on and key switch on. But after it is started it no longer works.
Do you know what other 2 wires or positions on the E38 ECM? I don’t see them on my pinouts sheet. Thanks for the help.

Re: 6L80 transmission rebuild, relearn, & TCC wiring
 

FYI. Since I have not heard of a way to get the ECM to recognize the brake switch while running in the apply or release state I set the TCC release 1st gear at 0% throttle position to 3 mph. At or below it unlocks the converter. Now the truck does not act like it is going to die coming to a stop sign. I know it would be better to see the brake pedal but I can’t figure it out. But the truck is much better to drive around as it doesn’t want to die at every stop sign.

Re: 6L80 transmission rebuild, relearn, & TCC wiring
 

You need a good scanner. Scan under the engine section. Then go to cruise data. This will show the brake signal with it running or not. The bcm brake signal only works will the engine is running but the bcm is not needed.

Re: 6L80 transmission rebuild, relearn, & TCC wiring
 

I've been working on this too. If you followed LT1swaps wiring diagram, the brake position sensor wiring isn't mentioned. I found it on another wiring diagram, but here is the short list:

On connector J1 (X1)
Pin Wire Function
26 0.5 YE Brake apply sensor signal
42 0.5 BN Brake apply sensor low reference
54 0.5 WH Brake apply sensor supply voltage

Here is the pdf with all the wiring https://www.gmupfitter.com/publicat/...lec_080212.pdf

Re: 6L80 transmission rebuild, relearn, & TCC wiring
 

X1 pin 57 is the brake wire you need. It gets 12 volts with brake applied.

Re: 6L80 transmission rebuild, relearn, & TCC wiring
 

What you have posted works only when the key is on the on position and the engine not running.
As soon as you start the engine this no longer works.

I am on a college tour with my son in Idaho and Montana.

I will be working on this when I get back next weekend.
But thanks for working on it. An A6 trans is its own animal and is not simple.

Re: 6L80 transmission rebuild, relearn, & TCC wiring
 

Hope you get your sensor soon. I can’t wait to see what happens.

Re: 6L80 transmission rebuild, relearn, & TCC wiring
 

I have done over a 100 swaps with the 6l80e.(seriously) If you scan your transmission or ecu engine section you will see that it works. I feel you are scanning your bcm or only looking at the brake position. Brake position is different than the cruise/tcc brake signal. Your transmission only cares about that signal. Tomorrow i will do a youtube video to demostrate this.

Re: 6L80 transmission rebuild, relearn, & TCC wiring
 

Hey Jason I am sure you know what your talking about.
When I get back I will for sure check it out. This is a swap into a 70 c10 so no BCM.
I am using hptuners and even if I am scanning the incorrect parameter the TCC does not unlock when I apply the brake. I did go into TCC properties and set the TCC to unlock when the truck throttle position is 5% or below and a speed of 5mph. Now the truck comes to a stop nice and doesn’t act like it’s going to die.
I will check out the video.
Thank you
Edit: it’s a 2011 lc9 6l80e with a e38 computer

Re: 6L80 transmission rebuild, relearn, & TCC wiring
 

https://youtu.be/986QmZKDRxs

Here is a quick video demo showing how to check the brake signals

Re: 6L80 transmission rebuild, relearn, & TCC wiring
 

Also something is going wrong. The tcc does not lock in first and second gear. It should only lock in 3,4,,5,6.it should only lock in those gears to help with fuel economy. It should not lock in wot either because the stock clutches cannot handle the power.

Re: 6L80 transmission rebuild, relearn, & TCC wiring
 

Pic

Re: 6L80 transmission rebuild, relearn, & TCC wiring
 

Well its been months since i have worked on this.
When I started this truck I didn't have HP tuners yet and had a few others work on it. Well I realized that the others did what they could but created problems with Torque management, Air flow, MAF Etc.
So i just put the truck back to 100% stock, PCM and TCM. Wow what a difference in how the truck drives.
Of course the shift points and firmness of the shifts are not right but I am going to start slow and take 1 step at a time.
Starting with the tune I received from Mike at Century Transmission to take advantage of the new parts in the trans I received from him.
Then I will work on the TU/TD.
Then correct the shift points and shift firmness.

Anything else you can think of???