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4l80e tcc

W

Wolfrida

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So ive been having tcc lockup issues it just wont lock and if it does its extremely rare. So the other day i was driving with a code readed and i hit erase codes though i had no codes no pending and it locked as soon as it said erase done. It stayed locked till i let off, then wouldnt lock again until i hit clear again. Again there are no codes no pending? Its been suspected that my pcm is bad. I dont think the misfire monitor even has time to think in between the last time i cleared it and when it wont lock
 
A scenario that happened to a friend.
His 2005 Escalade would not come out of park. Step on the brake and no give in the floor shifter. He was parked in front of the post office.
He called Me and told me what was going on.
I told him that it sounded like a ground problem. He said He was going to hook his code reader to it. He hooked it while we was still talking. No codes. He then steps on the brake pedal and the shifter comes out of park. I told him to drive it over to the transmission shop. He does, then He shifts to park, steps on brake and it functions every time. The technician comes out to see what the problem, he disconnects the code reader and the problem reappears. Hooks the reader and shifter functions just fine.
Tech removes the shifter cover and finds a ground wire had somehow come disconnected. Hooked up that ground wire and problem fixed.
Could a bad grounding wire be Your problem ?
Very possible.
 
@Wolfrida give us a little more info on what vehicle your are working on. there are a few thing you can possibly check that might not show a code on the PCM. also what kind of scanner are you using. some of these scanners don't have to provisioning to read or display tranny codes.
 
Its an 06 Silverado 2500hd. I can check the name of the code reader after work, it has given me a tranny code prior to the rebuild. It's odd because somewhere around 60 miles per hour the engine light flashes as if it has a dead Miss but it's running nice and smooth and it doesn't give a code for the cylinder other random codes have come up just one time and never again for example the coolant sensor but it reads correctly. My trainee guy isn't positive but he is suspecting a computer he says everything is reading what it should but the computer is not commanding TCC
 
My 2007 work van has had a random misfire code for years the shop can't get to the bottom of but that thing shifts like a dream no torque converter lockup issues ever heck that thing will sit idle with a dead mess at a light and still lock up it's got the same 6.0L 4L80E that my truck has
 
There are a few things that will keep the computer from commanding the solenoid to lock up the TCC.

Trans temp is one, needs to be warmed up
Brake switch is another
Engine coolant temp sensor will also play a role

There are others too but these are the main ones i can remember. Make sure your coolant temp signal is good and brake switch is working
 
on the brake switch there are two switches built into one. check if your cruise control works. if that works without turning off and tap the brake for it to disengage, then your brake switch is good.
 
And with the proper scan tool You will be able to read the temp sensor.
The temp sensor is in the coolant/thermostat cross over. It is not the coolant temp sender unit located at the front of the left cylinder head.
If that temp sensor is faulty the TCC will never lock up.
 
Stoney said:
What are the symptoms of tcc not locking up.. as in what does the truck feel like when that happens?
Click to expand...
When the TCC is locked up there will be a significant drop in engine RPMs.
To test if the TCC has locked up, driving along, engine at operating temp and vehicle, IIRC, over 40 MPH. Slightly hold down the brake pedal. Engine RPMs should gain several hundred RPMs as the TCC is disengaged.
 
Yup! that's the way to test. on mine I have to be going at least 50mph since I had the rear end gears changed. if I slightly press the brake pedal the rpm will jump about 200-250 higher keep in mind on our rigs, the 4l80e will engage the tcc in 3rd and in 4th. it's much easier to feel it while in 4th.
 
4? You mean o.d. ? My veiwer in truck go's P, R,D,3,2,1. I broke the shift cable a long time back ( about same time everything else went wrong on it) bought a new one from AutoZone, had buddy put it in..(P.I.A.) . ever since then I can't pull the shifter down to 1st gear. It will only go down to 2nd on the shifter view screen.. not sure if D is suppose to mean drive or overdrive.. that's always confused me.
So 4 = D ?
 
Yeah 4=OD because trans ratio is .75 to 1 (over driving). That's why they call it overdrive, output shaft spins faster than engine

3=D because that's 1:1 or direct driving. Shafts spinning same rate input/output

2 and 1 are underdrive gears with ratios of like 1.5 and 2.5 to 1. Engine spins faster than output shaft.

Sounds like your cable is out of adjustment, there should be a way to adjust that back in I would think.
 
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