Hi All-

I have a 90 454, 2wd 3/4 ton efi Suburban. It needs a trans rebuild.

I have a 2000 4l80e with known history. In the 1991 model year the Suburban came with a 4l80e, first year.

I have schematics for the 1990,1991 and 2000 Chevy van the trans came out of.

In comparing the scheamtics the 2000 schematic shows a few different control lines for the 4l80 than the 91.
EDIT: Not any more control lines, they both have A-M terminals but label the wires differently

SO the question is--
Did the method of controlling the 4l80 change through the years?
It does appear the pinout changed from 91 to 2000?
In the 91 schematic it shows a force motor, but not on the 2000?

Thanks for any help.
JOhn

 

You might check the forum at 454ss.com
I know at least on guy over there swapped his ecm and repinned the wiring harness to make the swap.
Typically the best way to do the swap requires a 7060 ECM, and a DRAC. The DRAC needs to come out of a vehicle with the same gear ratio and tire size.
You might benefit from a wiring diagram that comes with the improved trans wiring harness (screw on vs snap on).
OR you could just find a donor truck with a 4L80E and get all trans related wiring up to the ecm.

 

JX- appreciate the info.

What is the DRAC?

That is what I planned on using the 7060 ecm and getting a factory harness.

My main concern was the differenct in nomeclature

 

Digital Ration Adapter Controller, it's a small white box usually behind the glove box of the pick up trucks. Put drac in google, there is some good info.
The guy at 454ss.com had a real hard time believing me when I told him he needed a drac. I may be forgetting some details, maybe he was doing a speedo cluster swap also because there was some disagreements about the drac only used with the later type speedo clusters.
I'm not the most informed about this swap, but I know it's very common to go from a 1990 454ss with a th400 to a 4L80E with the newer ecm and drac. You can find all the info on that site I'm sure.
I have a '92 C3500 with a '98 4L80E, it originally had a 4L80E, there are no major changes in the wiring to or in the trans. I got my trans and 2 feet of wire off a donor truck and the colors were off a bit, it wasn't until someone sent me the instructions for the updated harness that I figured it out because those instructions list all possible wire colors for every application that came with a 4L80E.

 

JX- OK so the new 7060 will require the drac, my 90 won't have a drac already--correct?

Sounds like I need to find a truck that is all there and take what I need.

Does it matter if it is a small block truck?

John

 

This might help at some point.

 

It doesn't matter if it's a small block truck but you will need to put a big block memcal in the ecm.

As far as I know the 1990 does not have a drac, I think it was built into the speedo for those years.
You might find a better answer by looking for it in the truck or looking at a wiring diagram.

 

That picture is perfect, I was going to create that info in an excel spreadsheet.

I am still going to do that to consolidate the info.

I just confirmed the 90 and 91 have the drac.

 

Yes they do, but the DRAC is located in the instrument cluster itself. This website should help may have to be a member though.
http://www.fullsizechevy.com/forums/...1-post279.html

 

I pulled 2 dracs out of 90 and 91 burbs...
I believe they were behind the radio. They are sitting in a box in my garage.
If you need one, let me know, you pay the ride.

 

You are looking at cluster from an 88-up c1500 truck. burbs and blazers did not change dash clusters/body style until 92...