I just bought a rebuilt 4L60E tranny for my 2000 Silverado 1500 4x4,when I first went to drive it the tow/haul light was on and I couldn't get it to turn off but I drove it and no shift,it stayed in low gear,but after reading that a 2004 tranny and a 2000 has different wiring inside so I changed the wiring and I used a 2000 year wiring harness inside the tranny but still no different,so it must of been a freak of nature that my wires broke leaving my shifter and they looked like it was grounding out so now my tow light is off but still no shift,it acts like the wiring harness isn't even connected to the tranny,

 

Does the speedometer work? If not.....Check that your VSS is plugged in. 4x4 truck have a jumper harness, So there is 2 connections that need to be checked.

A 2000 & 2004 4L60E is electronically compatible with each other, If the trans is left unplugged.....It will start in 3rd gear.

 

yes the speedo works and it starts off in low gear,it goes in gear quick and solid,reverse and low that is,

 

The wire for the tow/haul *** button breaks quite commonly on those trucks. I drove mine for about 3 months in tow mode because the wire was broken. As for the no shifting I can't really help you there..

 

I'm guessing this was a cheapo "rebuilt" 4L60E off craigslist or such?

Any trans codes stored in the PCM? Do you have a way to read live data?

 

Yes the speedo works great,I've rechecked the pins in the plug to make sure no e was damaged or bent over,I changed the internal wiring harness but no change,and it's not bring up any codes,the check engine light in not on an when I hook up a reader it says none,the fluid is new and full,any forward gear I put it into it only has low,if I try to manual shift it just low.