Ok, truck and trans are a 1996 1500 w/ 1996 4l60e. trans shifted fine behind the 5.0 vortec, did a 5.3 swap with a nelson harness and now, the trans starts out in 2nd and wont downshift (manual or auto) and it also apperas overdrive isnt working, any ideas where to start, sounds like the tuning, but i can get a responce ot get nelson to answer the phone. Thanks

 

If you have access to a scanner of some sort take a look and see what codes it's kicking. It sounds as if it's in limp mode which would imply an incorrect harness or maybe even a ground wire that's not properly installed.

At the very least go over the harness connections with a fine toothed comb to make sure that everything is plugged in where it should be and there are no issues with your work. That's the first place I start when I have issues with a fresh build.

g

 

With a complaint with no 1st or 4th the first thing that comes to mind is an issue with either the 1-2 shift solenoid or the wiring for it. You said the trans starts out in 2nd. Does the trans up shift to 3rd auto or manual?

 

Problem is nelson locks the PCM so local guys cannot alter your tune to help. I'd like to see the set-up and I have efi-live. I'll scan it and see what is being commanded. I think you are local to me. name is Rodney... cell 270 4829

 

had a chance to drive the truck a little more yesterday, after the truck is first started up, the trans will shift fine(1-2-3) the first time and then after that, it will not down shift and then it will ony down shift to second manually, overdrive is engageing if you let off the gas, but as soon as you give it any throttle, it disengages and stays in 3rd

 

possibly, the shift solenoid like stated earlier, you just gotta keep calling man youll get thru, but only leave one message, leaving a bunch of messages will just keep pushing it further and further down the list, i dont think its the tune, but maybe he would have a suggestion.

 

ok, I think Ive found the problem, it seems the connector pins on the 96 4l60 and the newer 4l60 are different, I need to repin the connector and it should be ok

 

I do not believe this to be true as far as the transmissions connector unless you are referring to the ECM side of the harness.

 

Check to make sure you have supply 12 volts on the pink wire at the transmission connector. Without power to the transmission the shift solenoids cannot operate and it will start in 2nd gear as a result.

 

Well, the connectors are the same, the wiring is right and I have 12 volts on the e-pin(red on the Nelson harness). I guess I'm gonna change the solenoid tomorrow and see what that does