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4L80E swap

M

ManicTim94

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I have a 4x4 2001 silverado that has a 6.0 out of a 2003 2500HD. The 4L60E that was behind it took a crap and I bought a 95 4L80E that had a 350. I have it all bolted up, but my issue is the cross member and the drive shaft.


Any tips would be greatly appreciated as I have bitten off more than I can chew. I bought a new torque converter and flywheel. Matched uo very nicely. But my crossmember doesn’t match up. Was wondering if y’all had a part number for a new one? Also a prt number for a drive shaft that will fit??And also, the computer. Will it work with that trans?
 
Someone might know part numbers that could work- not me. My method has always been to just weld up a new crossmember. If you can’t, there are shops that can for you.

On the driveshaft- there are shops that do that, usually do that along with axle and rebuilds and such. If you post your general location like what city- if there are people here that know the area, they can recommend good shops for that stuff.

Like me, I am basically @ Las Vegas, Nv. Here is a shop called Adams Driveshaft. You could drop them the truck and they could build the crossmember and make drivelines well and affordable.

Idk what it takes for that computer to work, I would recommend a stand alone unit.
 
Welcome to the forum MT 94.
I would think around the Chicago area there would be plenty of shops that could do the work, but, to find a good and reliable shop would be the main concern.
Lots of stories of people thinking they picked a good shop, only to get screwed over and have to find someone different to complete their project.
 
MrMarty51 said:
Welcome to the forum MT 94.
I would think around the Chicago area there would be plenty of shops that could do the work, but, to find a good and reliable shop would be the main concern.
Lots of stories of people thinking they picked a good shop, only to get screwed over and have to find someone different to complete their project.
Click to expand...
Let us know if you find a good drive shaft shop.


I don't know if Bourbonnais Truck supply still is around or if they do driveshafts anymore.
The last driveshaft they did for me, I had to take else where to get rebuilt. They were always the go to place around here.

There was another good place just north of Rt 30, or maybe it was Rt 80, between I57 and Indiana.

Last story I heard was they closed shop because the area was so nasty. Couldn't sell the building for any decent money and were too old too start over.
 
Yeah I’d have to look into shops around here. My thing is, funds. At this point I currently have it all ready to go except I can’t get it started. Idk if it’s the pcm related issue, neutral safety switch, or starter.
 
the ECM might match up but you will probably need the harness to go with it. was the original engine a 6.0? if so, you may need to change out some of the sensors and use the ones from your 2001 to make it work with the 01 ECM.
 
The original engine in the truck was a 5.3. Swapped it with a 6.0 from a 2003 2500HD. (This was done by previous owner). Everything was swapped and working until he shredded the trans by not tightening the converter bolts all the way. (It was a 4L60E) I bought it from him and bought this 4L80E to put in it. It came from a 95 K2500 with a 5.7. It came with transfer case and torque converter. But no harness. The harness off my 01 (or 03 since computer was changed) plugs into the trans except for one speed sensor, which I heard would still work. Just didn’t configure the computer part of this until it was too late. Now I’m scratching my head.


Sorry to reiterate, just want to paint a better picture for you. Thanks again.
 
Ok. I think I’m following you right. After connecting up the 95 trans now it won’t start up the engine.

Is it just not cranking over or it’s cranking but not fireing up?
 
Not cranking over would possibly be the neutral safety switch ether in the incorrect position or the wire pin out is different from the old tranny. Iirc the NSS should be interchangeable from the old tranny to the new one. Try just connecting it to the harness without installing it. Just make sure the tranny is in park or neutral before cranking

If it’s turning over and not starting. Disconnect all the tranny harness connectors and try the engine to see if maybe something is shorted there causing a no start condition. You might need to recheck fuses too
 
Something else that just came to mind too is the onboard security system VATS, passkey or pass lock on the factory ecm. Is that enabled or connected? This would be one cause of a no crank condition as well
 
It’s not doing anything. Not even cranking over. Think it might be the NSS. Will have to look at it all tomorrow. And the info section of the dash cluster only says my battery is low and to service the 4x4. Which would be due to the fact I have to connect the t case electronics still. I noticed that my PRNDL doesn’t say what gear I’m in.
 
Yeah, that sounds like the NSS is the issue. it might not be the same internally even though the connector fits. do you still have the old 4l60 that was in the truck? if so. set the 4l60 in neutral, mark the position of the NSS and carefully remove it from the tranny. make sure the installed tranny is in neutral and the parking brake set. simply connect the NSS to the harness without installing it. key on and see if the PRNDL shows neutral and it should crank over. once you have verified this. mark the position of the installed tranny gear sector rod and shaft. remove the installed NSS and replace it with the one from the 4l60 keeping it's same position. key on don't crank it just yet. shift the lever through each gear and verify the PRNDL display shows each gear and "feel" for the shifter to go in each catch on the tranny as you go though the motions.

iirc these NSS's are adjustable and they can get so far out of adjustment that it can show in park and actually be in reverse!
 
something you may also keep in mind is the pin configuration on the 95 4l80e may be different than your 01-03 harness. I think I have a diagram of the tranny connectors on the 95, but not on the newer ones. if you can find the diagram, verify the pins in each connector are the same. GM did change things over the years, if you find this to be the case. you might find it simple to drop the pan on both tranny's and swap out the internal harness and connectors to make it all work.

again I am no tranny expert, @THEFERMANATOR can verify this and tell you a whole lot more very useful info.
 
Thank you for all this advice. And I’m hoping he does share his thoughts here. I will go and mark those spots you said and see how it all goes today! I will also add whatever I did to this thread that worked and verify it all so you guys and whoever else can use this information
 
The prognosis is, the valve solenoid the on the transmission is loose and wiggling and because of that I can’t get the egg shaped connector on it without it pushing into the trans mission. But everything else went together goood and the truck is don’t excel to for that issues. Is it fixable? Or do I need a new trans?
 
dbrannon79 said:
something you may also keep in mind is the pin configuration on the 95 4l80e may be different than your 01-03 harness. I think I have a diagram of the tranny connectors on the 95, but not on the newer ones. if you can find the diagram, verify the pins in each connector are the same. GM did change things over the years, if you find this to be the case. you might find it simple to drop the pan on both tranny's and swap out the internal harness and connectors to make it all work.

again I am no tranny expert, @THEFERMANATOR can verify this and tell you a whole lot more very useful info.
Click to expand...
Internal harness was busted. Dropping pan to replace it and the pigtail for it just to make sure it’s all good.
 
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