4l80 trans questions

[LouisO87]

ok so im in the process of wiring up my 04 5.3 ls into my 97 1500. ive got it running and most of it is done but i have a few things ive ran into. I have no clue where the ls harness came from or who made it, it was supplied with the truck when i purchased it and had never been hooked up.

#1 tcc- so coming out of the standalone fuse box their is a white 12 gauge wire thats labeled "brake". if i hook said wire to the purple wire that has constant power but loses power when brake is applied its not right. with or without the wire hooked up truck shifts into 2nd pretty quick and then will stall out when brake is applied. So im wondering if this wire should possibly be tied onto the wire that gets power when brake is applied? If trace pin #33 on the blue ecm plug to see where it goes thru the harness it goes to the supplied ls fuse block. WITHOUT hooking up the white wire labeled "brake switch" the purple at pin 33 has constant power with or without the brakes being applied. from my understanding pin 33 should go from the ecm to the purple wire on the brake switch. I pulled the relay labeled tcc and the purple wire at 33 lost power. so i left the relay out and ran a jumper from 33 to the purple on my brake switch. it has power with key on at no power when brake is pushed. tried it out and it does the same thing shifts thru gears then when you stop it stalls out like how a standard would if you didnt push the clutch.

tachs not working but have it figured out just need to get a resistor.

ive researched and researched and researched but have yet to find another harness like mine that has the manual with it or anyone else thats ran into this same problem

 

[KansasOBS]

ive reseached and researched and researched but hav yet to find another harness like mine that has the manual withit or anyone else thats ran into this same problem

Grab an ohm meter, pull your blue plug, and make sure that white wire is indeed connected to 33.

I admittedly just connected 33 to the purple at my cruise, and sent it. Never even checked.

 

[LouisO87]

i just edited the post after doing just that.
sorry just a lot to retype lol. in a nutshell pin 33 runs to standalone fuse box with relay labeled tcc. without hooking up the white wire to the brake switch it has 12 volts no matter if brake is applied or not. pulled the relay and ran a jumper from 33 purple all the way to brake purple. key on has 12 brake pushed 0v. took it on a test run and its still doing the same thing

 

[LouisO87]

ok i think i figured out the problem. im going to by pass the tcc relay and hook pin 33 straight to the brake pedal that way it works like it should. the trans issue i belive has to do with tuning. im throwing 2 codes p 0785 and p0740 which is consistent if the pcm is tuned for a 4l60 and not a 4l80. im going to hook back up to hp tuners and verify and correct it if thats is n fact is true

 

[LouisO87]

Ok so changed the trans in the computer from a 4l60 to a 4l80 and rewrote the program and still doing the same thing

 

[KansasOBS]

As long as you have it correct to power, then no power when brake applied going to 33, I would imagine it would still have to be in your tune, or an internal fault in the transmission. There's not much more to it, in that area.

They probably had that relay in there for older vehicles.

Sorry I dunno much more, I sent my pcm off to lt1swap when it came to all of that. There are others around here that know the tuning and transmissions a million times better than I. Maybe they will see your problem.

 

[LouisO87]

Ok I figured it out. The tune file has a 4l60 file loaded. Couldn’t find the correct one to do the correct segment swap. I had another pcm for a 6.0/4l80 so I went in and unlocked it and tuned it, put it on and it fixed the issues. I wound up bypassing the relay on the tcc lock also. First time getting to drive the truck since the build and I am very happy with it. Still need to hook up the speedo, tach and temp sensor and then wrap everything up and clean it up better.

 

[yevgenievich]

Sounds like main issue is solved. On the tcc part, there are two styles of brake switches and sounds like harness had a relay to convert if you had standard older style brake switch. Reading 12v all the time on that wire means it was on a ground side of a relay coil and would turn the relay on if grounded.

 

[KansasOBS]

Sweet, glad you got it. I was really wondering if something went wrong in the tune swap after you mentioned it. Just finished mine up about a month ago as far as the LS swap. There was stuff I wanted deleted in the tune, and figured it best to let someone else handle it, instead of a complete noob, after all the other changes I had made also.

Tach is all I'm missing here, resistor is laying over in the toolbox. Been too cold. I figure there is a rev limiter if I put'er in the ketchup anyhow.