Torvus

2005 4.8L with stock wiring harness. No mods.

[PCM] P0740 - TCC Enable Solenoid Circuit Electrical (Old) (Current) (Immature)
[PCM] P2761 - Torque Converter Clutch Pressure Control Solenoid Control Circuit/Open (Old) (Current)

Transmission is a stage II with trans brake by Jakes just installed with stock torque converter. Pin E has power. Not sure where else to check.

One thing I'm concerned about is I've been working on what I believe has been a rear brake pressure issue because when in gear the brakes won't hold and the rear wheels just spin. The brakes were pretty warm after a few seconds of this and I'm starting to wonder if the issue is with the converter not slipping at low RPM thus the rear brakes won't hold but to me that seems pretty far fetched however the errors above are a concern.

I'm using the stock 2005 wiring harness only changed the configuration to 4L80E in the configuration with HP Tuner.

I have been unsuccessful in trying to narrow this down online and the few posts that have similar issues have gone incomplete or unanswered.

Any help would be greatly appreciated. I have a car meet coming up at the end of May and we are working frantically to get this thing on the road.

Jake's Performance

iTrader: (2)

If you are using a harness originally for a 4L60E and a 4L80E segment swap in the PCM, you need to swap two wires and unpin one.

I'll dig out the diagram and instructions, but I'm fairly certain this is your issue given the codes you have.

Torvus

That would be awesome!

Jake's Performance

iTrader: (2)

Torvus

Awesome! Thank you sir. I'll give it a shot as soon as possible.

Torvus

It appears that theres an aluminum plug inserted where the front ISS sensor should be located on the 4L80e. Is this not used or do I need to try and hunt down a sensor for the front to keep in line with the doc above?

slow67

iTrader: (2)

With a 4L80E tune, you need the front ISS sensor (which is the same as the rear, so you should be able to pick one up at an auto parts store).

Torvus

Thanks for the info. I'll pick one up tomorrow and see if I can get it wired into the ECM. I believe that most after market transmission controllers elliminate the need for the ISS, but being that I am using the stock harness and wiring for now I'll definitely need it.

Thanks again all. We'll see if this resolves the issues I'm having.

slow67

iTrader: (2)

Don't forget that you could use almost any late model VSS harness (from the PCM Pin to the plug) for the ISS sensor harness.

Jake's Performance

iTrader: (2)

I'm pretty sure it's the same as a GM ECT sensor as well. You can get the pigtail at any decent parts store.

Torvus

Found the sensor and pig tail at the local hardware and wired into 22 and 23 on the Green ECM. Followed the instructions swapping the white wire for the brown and at this time I'm getting the following with the tune set for 4L80E in HP Tuner.

[PCM] P0740 - TCC Enable Solenoid Circuit Electrical (Pending) (Old) (Current) (Immature)
[PCM] P0785 - 3-2 Shift Solenoid Circuit Electrical (Pending) (Old) (Current) (Immature)

Car is about mobile. Took it down to the mail box and it shifted extremely early to about 3rd gear and wouldn't downshift until I pretty much stopped.

This is my last week to have the car ready before taking it to the show on memorial day weekend so running out of time. Any thoughts?

Torvus

I'm thinking the issue is that the PCM is still looking for a 4L60E configuration. The S wire is the 3-2 per pinout and this is the code. This code showed up after I swapped the wires on te transmission connector. Any suggestions on what else might need to be changed in the tune?

Jake's Performance

iTrader: (2)

The entire transmission segment.

Torvus

Just sent off the two files to HP for a segment swap. Hopefully have them back by tuesday or Wed.

Was tempted to just buy a transmission controller but only have a few days left before heading out to the show and trying to just get this thing on the road. I appreciate all the help. You guys have been great.

Jake's Performance

iTrader: (2)

Give me a call at the shop today. I'm going to help you get it going quicker and better.

Torvus

Just read this but guess I missed you guys. I'll try to give you guys a call tomorrow?

68 TT

From what I have read it is also the same as one of the connectors on the external coil distributors from the late 80's & early 90's that connect to the external coil.

Haven't had a chance to verify this though.

Torvus

Wanted to take a minute and thank Jake and Jake's performance for their help with my issues. Outstanding customer service and thanks to this we'll be making the show this weekend.

Again, thanks for all the help. It's truly appreciated.

jesse2019

hey so I recently did a 4l80 swap on my truck and I’m currently getting the p2761 code that you were getting as well were you able to find the cause of it? Thanks In advance