4L80E Harness Adapter

I am working on my father in laws 1991 Chevy suburban 3/4 ton 4x4 6.2L Diesel w/ 4L80E transmission.

He replaced the filter/fluid and lost reverse, couldn't figure out why so he asked me to replace the transmission, he got a used transmission from a local yard (the only one that had one), it came out of a 93 pickup w/ 5.7L, well the main harness plug is different.

The old tranny has a 12-pin connector w/ center bolt. the new one is a 11-pin and just clips on. Anyone know why they are different or where I can buy an adapter for it. I know they make adapters to go from the 4L60e to a 4L80e.

I do know the new transmission is a remanufactured transmission (has a sticker on it) so that could be why it has a different harness.

any suggestions?????

Joe

I am working on my father in laws 1991 Chevy suburban 3/4 ton 4x4 6.2L Diesel w/ 4L80E transmission.

He replaced the filter/fluid and lost reverse, couldn't figure out why so he asked me to replace the transmission, he got a used transmission from a local yard (the only one that had one), it came out of a 93 pickup w/ 5.7L, well the main harness plug is different.

The old tyranny has a 12-pin connector w/ center bolt. the new one is a 11-pin and just clips on. Anyone know why they are different or where I can buy an adapter for it. I know they make adapters to go from the 4L60e to a Le.

I do know the new transmission is a remanufactured transmission (has a sticker on it) so that could be why it has a different harness.

any suggestions?????

Joe
Are both old and new transmissions 4L80E setups?
I would use the wiring from old transmission.
If you still have the transmission that came out of it remove the wiring inside wiring harness and plug-in from it.
And Also check the solenoids and sensors from old transmission if the new transmission solenoids are different.

I don't think the 93 with 5.7 came with a 4L80E trans? Both trucks 3/4 ton? I may be wrong but... I think there were some changes around the 91 / 92 year model.

GM changed the harness in 1993 from a 12 pin to a 11 pin as they were experiencing a transmission leak. You can either replace the 93 harness with the old 12 pin harness or what is recommended ... buy a 4L80E transmission repair end for 1994-2002 vehicles ....runs about $50 from electronic advantage. See eBay. You have to cut the connector wiring harness and splice in the 11 pin connector... only cut one wire at a time....you will have one wire left over you just tape off. Make sure there are instructions included....you need the pin out.
Bill:licka:

Difference is as someone commented early (12 pin) vs later (11 pin) 12V+ power was on 2 pins early-pins C & K later style put 12V+ on one pin only-pin E
A diagrahm of the plugs with each pins ID letter and a chart of of the funtion of each pin (by letter) may be viewed at www.pirate4x4.com (http://www.pirate4x4.com)
search the forum thread YJ wrangler 6.0L 4l60e rewiring harness This may be bulletin board#post8030893 It address converting for a 4l80 from a 4l60 but contains the info on early & later plugs.