99 4L80e in 93 6.5

[Tommy9103]

So this past weekend I bought a 93 6.5 dually with a bad transmission (fluid pump went out). I have a 4l80e sitting in my garage out of a 99 vortec truck 2500 so figured what the heck and stabbed her in this morning. I put the diesel converter in it) and when I went for a test drive the trans felt solid as a rock but will not shift threw the gears in any way at all not automatically nor manually. Any guidance would be greatly appreciated. Thank you.

[trbankii]

What was in the ’93 before - another 4L80E?

[Tommy9103]

Yes it had a 4l80e to begin with.

[trbankii]

I’m guessing that the ’93 is mechanical injection, in which case the control of the 4L80E was a separate computer from the ECM. I think that after going to EFI, the control of the 4L80E was all integrated. I’m not sure if that makes a difference between the two.

[DmaxMaverick]

Simply put, 93 and 99 model year 4L80E transmissions are not compatible, in either direction, without accommodation for the original technology.

[Tommy9103]

What would it take to accommodate?

[trbankii]

Simply put, 93 and 99 model year 4L80E transmissions are not compatible, in either direction, without accommodation for the original technology.

That’s sort of what I thought, but I wasn’t sure. So the standalone computer from the ’93 won’t run the ’99 trans and swapping all the electronics from the ’99 to make the trans run isn’t likely a viable solution.

[Tommy9103]

So would I need something like this to work it as it is a cheaper alternative to a rebuild and it gives me some control of my shift points and pressure which would be nice to have. https://www.ebay.com/itm/131557581243

[DmaxMaverick]

Yes, that should do it, IF it works as advertised. I'm not familiar with that product, so I suggest some research. The price is about 1/2 that of a competitor's known-good product with similar features. This usually means it's a hype-up hack, or a clone.

I make a lot of Ebay purchases, so there are some things that caught my attention. First, the seller has a 100% score, with no negatives or neutrals, but is showing only 149 posts spanning over a year. That usually only means products ship as promised, and very rarely indicates the actual performance of products. The seller has a phone contact number (a very positive trait, if the call is answered), so I think you should start there with any of your questions or concerns.

As an installation and compatibility comment, your 93 truck should have the electrics/electronics (TPS, etc.) necessary that would otherwise have to be added to a later EFI model. This is common for later model trucks that are converted from EFI to MFI. If you purchase and put this product to work, please respond back here with your results and any information that may be helpful to other members. My interest is peaked, and I am sure I'm not alone.

[Tommy9103]

So after some light reading and contacting some transmission mechanics of mine I found there are really not much difference between the two electrically the 99should work just fine. So I checked all my connections and cleaned them thoroughly. Replaced the transmission ecm fuse and checked and rechecked everything. Then took it for a test drive. So to all the nae Sayers guess what go right ahead and throw yourself a 4l80 out of a 99 2500 series in because it works just fine. I had to adjust the shifter linkage a little to go all the way into park. And I went ahead and installed a manual tcc lockup switch while I was at it. This truck shifts smooth as can be and runs amazing.