I just swapped from a 4L60e to a 4L80e in my 2000 RC. I bought a Speartech wiring harness. The truck has been tuned for the 80. Now when I start the truck it acts as if it's in 2nd gear and the speedo acts as a tach. I broke the pmp switch(black on the side) when I unplugged the 60. I made sure all the prongs where back in and jb welded the outside which I've done on a truck previously. Also say speed sensor input is low on voltage. Any thoughts or ideas would be greatly appreciated.

 

If the speedo if moving at idle you have the speed sensor mixed up, change the connectors from front to rear one and rear to front.

 

Ok thanks I'll try that. Would that make trans think it's in gear too?