4L80E needs help!

[flattopwill]

Hey I know very little about transmissions so please bare with me.
I just got my '02 5.3 installed with a '96 4L80E in my '91 Chevy RCSB and Im having problems with the trans. It was bought used and hasnt been gone through. The tune was done by Nelson Performance and the wiring was done, checked, rechecked, and rechecked again by my friend who is a certified GM technician. He simply repinned the trans connector for 4l80e configuration. He, along with a GM tech transmission specialist say it only needs one speed sensor although all my research suggests otherwise.

Its hard to tell with a 2800rpm stall but I think the only forward gears it has are 2nd and 3rd. Reverse works fine. No 4th and no tcc lockup. I only get one shift and under light throttle it doesnt happen til about 35-40mph. It does succesfully downshift but only from 3-2.

The computer is giving codes:
TCC solenoid PWM
Trans pressure manifold switch

I took it to a transmission shop and they are scared to touch it since it is a conversion/swap. Their scanner said although it gave a code for pressure manifold switch the pms showed to be functioning. Also, a weird thing, the scanner showed a TPS angle (%) but the volt reading stayed at 0.00 at all times.

I did almost all the mechanical part of the swap but this wiring/computer stuff is over my head. Please help!

[casey23]

Hey I know very little about transmissions so please bare with me.
I just got my '02 5.3 installed with a '96 4L80E in my '91 Chevy RCSB and Im having problems with the trans. It was bought used and hasnt been gone through. The tune was done by Nelson Performance and the wiring was done, checked, rechecked, and rechecked again by my friend who is a certified GM technician. He simply repinned the trans connector for 4l80e configuration. He, along with a GM tech transmission specialist say it only needs one speed sensor although all my research suggests otherwise.

Its hard to tell with a 2800rpm stall but I think the only forward gears it has are 2nd and 3rd. Reverse works fine. No 4th and no tcc lockup. I only get one shift and under light throttle it doesnt happen til about 35-40mph. It does succesfully downshift but only from 3-2.

The computer is giving codes:
TCC solenoid PWM
Trans pressure manifold switch

I took it to a transmission shop and they are scared to touch it since it is a conversion/swap. Their scanner said although it gave a code for pressure manifold switch the pms showed to be functioning. Also, a weird thing, the scanner showed a TPS angle (%) but the volt reading stayed at 0.00 at all times.

I did almost all the mechanical part of the swap but this wiring/computer stuff is over my head. Please help!

GM buddy is wrong.... Now you have to see if he will fix the wiring... You need to install the other speed sensor adaptor... and fix the now messed up wiring......

[flattopwill]

Oh crap. Can you tell me what exactly needs to be done to the wiring? And i think my harness only has one speed sensor plug.

[flattopwill]

We plugged in a Tech 2 scanner today and logged me driving down the road. It showed the computer was giving the right commands. My wiring guy said he realized he misplaced the brake switch wiring and also that he would double check the rest. The misplaced brake switch wire explains why I don't have tcc lockup but does it necessarily explain my tcc code? Can anyone tell me what exactly needs to be done to use a 4l60e harness on a 4l80e? Nelson says their conversion harness just moves the pins around which is what my buddy did. ....please help

[RedHeartbeat]

The brake switch supplies power to the trans. No power and the trans starts in 2nd gear and you have no lockups. You won't have shifts either.

[flattopwill]

Hmm that's weird cause I definitely have one shift and also a downshift. I'll get him to connect the brake switch to the proper location and see what happens

[flattopwill]

So when I left work this morning i had all four gear for about 2 miles then it went back to its old self.........???? solenoid sticking maybe?

[flattopwill]

Got the brake switch wiring good to go...

So how come it shifts through all four gears when it is cold but then after it warms up it leaves me with just 2nd and 3rd?? Some one has to know....

[pl4yboy]

GM buddy is wrong.... Now you have to see if he will fix the wiring... You need to install the other speed sensor adaptor... and fix the now messed up wiring......

^^^

[flattopwill]

well if it works when cold i dont think its a wiring issue...

and how come im told it takes more than just repinning the harness but no one can tell me what it takes.