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4L80 no converter lockup, no cruise control

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DM88

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Hello all! I am new to the forum but have read through quite a few threads and have found a lot of great information. I have a problem that I hope someone has dealt with before, and would appreciate any insight to get it figured out.

I have a crew cab short bed 99 obs chevy 2500 4x4 with a 5.7 and 4L80. The truck had been neglected when I bought it, but I've worked through almost all of the issues and its pretty nice now. However, the torque converter does not lock up in overdrive, and the cruise control does not work. The transmission shifts perfectly in all gears, just doesnt lock up in OD. I have replaced the brake switch, engine temp control sender, throttle position sensor, have traced wires under the dash, removed the trailer brake controller, checked all fuses, had the transmission rebuilt with new harness and new torque converter, swapped speed sensors, made sure all lights are working (read somewhere that 3rd brake bulbs being out could affect lockup, although I don't really buy into that theory). When hooked up to a scanner, it says that the cruise control is disabled. I'm inclined to believe that the two issues are related, and that it's an electrical problem somewhere. Have any of you experienced something like this? Any thoughts on what I should check into next? Thanks in advance! -David
 
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Welcome @DM88 on your scanner, are you able to read data or trans codes? I would start there and see if the data stream shows the PCM commanding lockup. there should also be another switch on the brake pedal for the cruise that also controls the TCC engage / disengagement.

@THEFERMANATOR is the most knowledgeable person here for transmission that I am aware of, I'm sure others will chime in soon with additional help :)
 
Thank you. I don't have a good scanner, but when my buddy hooked his up, he did not find any codes or anything out of the ordinary. There is only one switch on the brake pedal, which is the one I replaced. It is not adjustable either. Tried unplugging it and that didn't make a difference
 
your's is an OBS2 system, you can get a cheap bluetooth code scanner and an app on your phone called torque pro. that should be able to read the data with the right PID file. another app I use is called car scanner pro.

look real good under the dash around the brake pedal linkage for a spot where a second switch might be missing. if the cruise is disabled, it could be missing that switch under there. I'll look online to see if one is listed for the cruise as a separate switch.
 
looks like it's combined into a single switch. make sure your pedal is up all the way. something you can try is driving while placing your foot under the pedal and lifting up on the pedal. also make sure all your fuses are good and none are missing. another thing is if all speed sensors are working. there are two on the tranny and possibly one on the diff too. but that would require a scanner to check.
 
Thanks for the response. I have tried lifting the pedal, no luck. I've checked all the fuses and wiring around the pedal. I noticed a couple burnt looking spots on one of the connectors coming from the multi switch where it plugs into the dash harness. Im going to try changing the switch and harness next week and see if that does anything.
 
There are several things that will prevent TCC lockup and CC not working. One of the first things I would check is what the scanner shows for engine temp, NOT the dash gauge but a scanner. Also check and see what the scanner shows for transmission temp.
 
Yes, the 3rd brake light MUST work for your cruise control to work and it can cause lockup issues. Unfortunately this is an electrical issue and will require a bidirectional scanner to do anything with. You're going to have to start by using a scan tool to see if the PCM can command the solenoids to work at all(key on engine off), then drive it down the road at hwy speeds and see if you can command lockup, or if it is inhibited. You will need a diagnostic flow chart to follow and go through. Situations like this where the parts cannon has been fired are normally more difficult as you now have to find the initial problem and hope no problems were created with all the work. But 1st things 1st is to check ALL of your fuses, inside and under the hood. Then get a QUALITY scanner on it and see if it is even commanding lockup. Don't worry about what it says for cruise control as that is a stand alone system.
 
Hi new on the tread I got an 02 4 wheel drive Chevy 2500 60 and tranny I lost reverse in it all the other gears work fine I have a 97 K 3500 with a 4 L 80 e in it I want to know if they'll just swap out without no problems at all it should from what I've read I don't know if somebody would chime in please give me some advice thanks
 
Dennyb said:
Hi new on the tread I got an 02 4 wheel drive Chevy 2500 60 and tranny I lost reverse in it all the other gears work fine I have a 97 K 3500 with a 4 L 80 e in it I want to know if they'll just swap out without no problems at all it should from what I've read I don't know if somebody would chime in please give me some advice thanks
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I dont have even a clue, welcome to the forum Denny.
 
Thank you all for the responses. When I can get my hands on a good scanner and get it fixed, I'll report back here with the solution.

As for Dennyb, the older transmission should work, but the 99 and up 4l80 uses the top belhousing bolt, which the 97 trans won't have, and not the next one to the right, since the 6.0 isn't drilled and tapped for it. So you'd be 2 bolts short on the belhousing. Also, the older style has the cooler lines close together on the side, the newer one has one to the front and one to the back to provide oil directly to the rear planetaries, a much better design. I wouldn't use the older one in your truck if I were you.
 
Yes sir your spot on on the bell housing. But the oil lines on the side are the exact same distance apart and the housing.and i noticed that. The holds the tranny to the trannsfercase. Is cast iron and the one on the newer one is cast aluminum they're the exact same bolt patterns and there are exactly two and three-quarter inch wide and the older tranny that was in a the one ton 4-wheel drive it had a PTO floor shift transfer case and the newer truck is a floor shift transfer case I already got it in I'll let you know how it works out thank you for your help
 
That is way more information than I know about interchanging transmissions and transfer cases.
Thank You Denny and DM88 for the responses.
I thought that surely some of them with more knowledge would jump in with some answers.
 
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