TCC constantly locking and unlocking

[monte4ever]

I've done the Flex Fuel sensor install using OS 12216125. After locating a 4l80e file that uses the same OS and performing a segment swap the trans would not downshift from third to first when coming to a stop. Hptuners support sent me a different file which solved the downshift problem but now the TC will not stay locked in 4th and when the shift selector is in D3 the PCM commands the TC to lock even thou in the tune it should not lock in third at all. In third when It locks It stays locked but in 4th it will constantly lock then unlock until I let off the gas to get below my targeted lockup speed. Hptuners support said that their segment swapper tool works as described so it has to be something on my end. Does anybody have any idea on what's going on or where should I start my search.

[monte4ever]

Here some more info, I got code P1810 - Trans Fluid pressure switch. My trans has less than miles on it after a complete rebuild. Could this switch to out that fast? Here's a thread from ls1trucks that describe my exact symptoms.

http://www.ls1truck.com/forums/diagn...1810-help.html

[monte4ever]

Here's a log of the TC locking and unlocking. It starts on frame 17:48:55. After it did this a few times I used the scanner controls and hit lock TC solenoid. The scanner did not lock the TC solenoid but some how it stopped the on and off locking until I went below the lockup speed. I tried it again and it repeated the on and off locking until I once again commanded the TC solenoid to lock which stopped the repetitive locking. Looking at the channels the PCM is commanding the TC solenoid to lock and unlock. IDK what's goin on.

Edit: Now I'm also getting a new code - P1637. This code says it's current and the P1810 code is labeled history.

[monte4ever]

I have dropped the trans pan and ohms checked the harness, TC solenoid, temp sensor, and replaced the Trans Fluid Pressure Switch. I'm also getting codes P1637 (Generator L- terminal fault) and P1810 (Trans Fluid Pressure Switch). I can hear the 1-2 and 2-3 solenoid click when commanded through the VCM controls, but I can not get the TCC to lock using the controls while sitting still or driving. Oddly, if I put the shift selector in D3 while driving the PCM commands the TC to lock even though the tune is setup to not lock in 3rd. I have all cells in the Apply/Release Speed table maxed out except 4th up to 50%. When it locks in 3rd it stays locked but in 4th it will lock and unlock repeatedly when it reach the lockup speed. After all my checks I've found zero issues with the Trans (unless I missed something) so I'm now leaning towards the PCM. I must add that at the same time these issues started my brand new Mechman Alternator sent close to 20 volts though my electrical system due to a bad regulator.

[Hutchinson]

I'll look at this tonight/in the morning for you bud,....I'm not real well versed on the 80e, I'm deep into the 60e's right now,...but, I'll give it a shake. What year/size truck, engine, etc? Did you do a PCM swap or change any wiring? With a 156OS, what PCM you runnin?

I looked up your P1810 code in my GM service manual, but couldn't find the P1637,...need your truck info though,...that may be why I can't find it. If your year is compatible with my service manual, I'll take pics of the DTC pages for you and attach them.

Maybe that could help.

[Hutchinson]

Can you also attach your tune?

[Hutchinson]

Cool man,....I have a call in with LexTech this morning, sorting some wiring on my 0411 swap/trans, so I probably won't have time till later this afternoon to research a bit for you. I'll also look again for the P1637 in my GM service manual for you. Your tune didn't attach for some reason bud.

[monte4ever]

It's attached now and I appreciate you checking it out.

[Hutchinson]

Evening man, I couldn't find anything in my GM service manual bout P1637,....probably a later year than what my book/truck would cover.

Here's what the GM service manual has for P1810 (again, not sure if it's same for your year, but could be). IMG_0336.jpgIMG_0337.jpgIMG_0338.jpgIMG_0339.jpgIMG_0340.jpg

[Hutchinson]

Sorry for the first pic man,....wasn't supposed to send that one,....that's what I'm currently working on with my 4L60e/0411 swap with LexTech.

[monte4ever]

Looks to be either the Trans Fluid Pressure Switch, wiring or PCM. The switch is eliminated because I replaced it two days ago and checked the wiring and solenoids.

[VodeAn]

Here some more info, I got code P1810 - Trans Fluid pressure switch. My trans has less than miles on it after a complete rebuild. Could this switch to out that fast? Here's a thread from ls1trucks that describe my exact symptoms.

http://www.ls1truck.com/forums/diagn...1810-help.html

When a newly built low mileage trans has low pressure issues (and it was not present before the new trans) there are usually only two possibilities...
Low fluid.
Transmission built incorrectly.

To confirm that there is actually low pressure put a mechanical gauge on the service port.
Make sure your VE table is dialed in, if it is off by a lot it can cause a low pressure situation.

[monte4ever]

Haven't checked pressure with a gauge but I'm quite sure that's not the issue, but I'm not ruling anything out. I believe it's a electrical issue that happened when my Alternator sent 20+ volts through the system.

[VodeAn]

Most 12v items on a vehicle are validated up to 18-20 volts but yeah beyond that sparky-arcy-melty-smelty.

[monte4ever]

It sent so much volts through there that my yellow top Optima puked acid (or whatever is in them) down the sides of it.

[VodeAn]

Impressive.

[monte4ever]

This goes to show you to never over look the simplest things. I re-adjusted my linkage and took it for a quick around the block drive right after a few days ago and it still would not go into overdrive so i parked it. Well, this morning I was headed to the trans shop and what do you know - I had overdrive SMH. I guess it took a minute for the ECM to pickup on the adjustment. I've been driving this car for years without touching the shift linkage but when i did check it it was off just under 1/8". I hope this problem is behind me.

[monte4ever]

Well, well, well, gusss what its back lol. Not playing around with this anymore. Gonna take it to a trans shop after I sort out a pulley issue. If it's a internal issue and I have to pull the trans I'm looking at a Performabuilt 4l80e.

[monte4ever]

Just wanna update this:
Turned out that it was a OS issue. This is my third 4l80e segment swap file and it looks to have taken care of the locking and unlocking issue however, now the converter won't lock when it's suppose to SMH. With each download the trans worked better than the last download. I think in my case this 12216125 OS segment swapped with a 4l80e file just don't wanna work together. Maybe if I find a 4th file a perform my 4th 4l80e Segment Swap it just might perform as it should. This has been a pain it the AZZ!!! At least I now know that it's not a mechanical issue.

Hptuners support, if you're here I can use some help.

[monte4ever]

Last update:

Trans is performing excellent with the last segment swap file I used. It wasn't locking when commanded because I forgot to use the gear change wizard. I wanna thank KingtalOn for the file.