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1994 4l80e to a 1993 2500 4x4 with same transmission

Otbc_gyro

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So I found a 1994 4l80e transmission for 600.00 that came available because the 6.5l diesel suburban it was in caught fire. The harness and speed sensors were melted but the trans fluid was clean and the owner claimed it had only 18000 km on it. After some time I had a transmission shop install it into my 1993 2500 4×4 with a 454 engine .

The truck is not showing any error codes, but it does not shift unless you let the gas off . I don't believe it goes into 4th at all and the kick down seems almost hyper sensitive.

I should also mention that we used the electrical from the 93 trans that was in there, but did not change the solenoids or torque converter. From reading here I think I understand some of the differences between the years, but was really hoping some one could offer some work around to make this 94 work I the 93 truck.
 
The short answer is you're missing the 40 tooth reluctor wheel that the output speed sensor reads on your 93. So the ECM doesn't know how fast you're going. You essentially have 2 different transmissions even though both are 4l80e's. There is 91-93, and 94+. They use a different valve body, 91-93 4x4's are the only 4x4 4l80e's to have a reluctor installed, the harness can be different, different style trans fluid temp sensor, and a different pressure control solenoid. You can either open the 94 trans up, add in the 40 tooth reluctor wheel, and swap valve bodies. Or you can get a custom prom burned for your ECM and add in the wiring to tell it when you're in 4low and hook up the speed sensor input to the ECM from the VSSB. The catch is your transfer case is setup so it only can use the 2 pin switch and not the 3 pin that tells 4low and 4x4, so you will have to make your own 4 low switch.
 
Thanks for your response. I guess I should have just had my 93 transmission rebuilt. I assume that by opening up you mean it has to be pulled out and basically rebuilt . Not something that can be done from taking the pan off.
 
Hey I’m new on here and I have a similar issue but haven’t installed a trans yet. I have a 93 k3500 4x4 454 with the 4l80e and the trans is smoked. A friend who is a builder said he believes it’s not worth rebuilding. It’s a plow truck but I can’t find a 91-93 trans. Mainly 95 and up. Can I make a newer trans work with minimal hassle? Is it worth it. I’m already looking at putting $2000 into a $4000 truck. Any help is appreciated
 
Hey I’m new on here and I have a similar issue but haven’t installed a trans yet. I have a 93 k3500 4x4 454 with the 4l80e and the trans is smoked. A friend who is a builder said he believes it’s not worth rebuilding. It’s a plow truck but I can’t find a 91-93 trans. Mainly 95 and up. Can I make a newer trans work with minimal hassle? Is it worth it. I’m already looking at putting $2000 into a $4000 truck. Any help is appreciated
It can be made to work, but I don't recommend it. Your options are to pick up a 94+ 4x4 trans, fully tear it down, install the 40 tooth reluctor wheel for the output speed sensor, your 93 valve body, and the correct shift shaft. 2nd option is to go with a stand alone trans controller. 3rd option is go to a 7427 PCM with the correct chip. The 4th option, we will call it the "redneck engineering" option is to find a 94+ 2 wheel drive trans that has the output shaft for a slip yoke, not a bolt on yoke(both output shafts are drilled and tapped for a bolt, so you have to check the spline depth to see which it is), cut the output shaft to the correct length, deburr, and taper it, install your 93 valve body, and the correct shift shaft. And the 5th option(my recommendation) is to rebuild your 93 since you know it is the correct model

As you can see, no option is really easy except to fix yours.
 
I don't know what shop labor rates are like in your area, but the hard parts (clutches, steels, seals, gaskets, apply pistons, bands, etc) in a Standard Duty kit is about $250 and in a Heavy/Severe Duty kit is about $350. Reman stock valve body about $200. New remanned OEM torque converter about $200. Add about 8-10 hours labor to tear down/inspect/reassemble without R&R of unit from vehicle, about $1,750 total.
 
It can be made to work, but I don't recommend it. Your options are to pick up a 94+ 4x4 trans, fully tear it down, install the 40 tooth reluctor wheel for the output speed sensor, your 93 valve body, and the correct shift shaft. 2nd option is to go with a stand alone trans controller. 3rd option is go to a 7427 PCM with the correct chip. The 4th option, we will call it the "redneck engineering" option is to find a 94+ 2 wheel drive trans that has the output shaft for a slip yoke, not a bolt on yoke(both output shafts are drilled and tapped for a bolt, so you have to check the spline depth to see which it is), cut the output shaft to the correct length, deburr, and taper it, install your 93 valve body, and the correct shift shaft. And the 5th option(my recommendation) is to rebuild your 93 since you know it is the correct model

As you can see, no option is really easy except to fix yours.

I was told that mine probably isn’t worth rebuilding. The fluid is black and smells. He said more than likely there is damage to the planarary. He said the cost work be significantly higher. Now I talked to a different shop yesterday and he told me they changed it in 96 not 94. The rebuilt trans I found is out of a 96 truck, but not sure that it is the original to that truck. But the tranny cooler lines are stacked like mine. The shop said if it has the same number of pins in the plug that it will work. My issue is that I’ve been getting mixed info from some pretty credible resources so I don’t know what to do. I just don’t want to waste my money and something not work.
 
What do I do if mine isn’t worth the money to fix? I can’t justify $3000 into a $4000 truck if I need to replace planataries and other hard parts
 
Not having the money at all is one thing. Having it and not justified is another. Get a junkyard trans and cross your fingers that it works and lasts a while. Then spend more money if it isn’t exactly what you need or doesn’t work or if it lasts 2 months and it fails.

What if $1500 fixed it then in 6 months the engine blows or the rearend fails—- you have to decide if you need the truck and if this is the right truck for your needs. If it is, then you make the longterm investment for it. If it isn’t then you sell it.

If you spend time reading on here you will find multiple people have a truck that kelly bluebook says is worth $6k but they have put $10k into it. The difference is if they didn’t then they would be buying a $20k truck to replace it. These trucks are longterm cost effective, IF you do it right. Half ass it and you’ll be crying half the time.
Want something this age that uses same engine/trans- get a hummer. I bought my 1995 in 2002 or 2003 for $26k. Any offer under $30k right now is an insult and I have put 120,000 miles on it. Really nice condition ones roll for $65k. Ut now you are playing investment car game vs having a descent old truck to work and rely on.
 
Black burnt fluid is burnt clutches, planetaries make noise. Worst case scenario your converter lunched itself. I don't like talking bad about other shops, but I assure you it IS 91-93 and then 94+ as far as how they operate electrically. The number of pins in the plug pertains to the 4l60e, ALL 4l80e's have 11 pins in the plug. Can't tell you how many PM's I get from people who see my post's about compatibility and ask me after the trans there shop said would work doesn't.
 
So I have a 1993 454 k3500 4x4 with a 4l80e in it. The original transmission all the sudden would only shift into first and second. So I got another transmission out of another 93 and it did the same thing. Then I ended up with a 95 and then finding out it wouldn’t work at all cause it’s a stand alone year. So I’m still confused why that it only shifts into first and second. Is it a bad ecm or tcm? I ended up getting rid of them but still would like to know. So my second question is I have a 94 heavy half ton with a 350 4x4 with a 4l80e in it. Is there any way that I can swap that transmission out of the 94 into the 93 with the 454? The 94 is a parts truck so idk if I could transfer the wiring harness over and the ecm & tcm and get them re programmed to work with the 454 or what ?
 
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