I swapped and 05 5.3 and 4L60e into an 88 C1500. I hooked the stock obs speedometer to the vss signal going to the pcm. It seems to work great, except at WOT. Under WOT the vss signal breaks down around 50mph and the truck wont upshift until I let off the throttle. Today I disconnected the speedometer and the truck upshifts properly. Any ideas on whats happening or how I fix it. Where are others getting their VSS signals from? I'm using circuits 821 and 822.
