Just finished a 4l80e swap. Used the Frost/PCM of NC (Relay) Harness. Went to back it out of the garage and no go.
Problem:
When reverse is selected, a horrible grinding noise occurs and doesn't stop until a different gear is selected.
(Best way to describe the noise would be trying to mash 1st gear in a manual transmission without the clutch, very horrible sound)
Tried:
Unhooking electrical connector on side of trans.
Jacking up rear tires, ran through N, D, 3, 2, 1. All work fine.
Went from D straight to R (with tires jacked up) and it engaged once! But only once and there was multiple attempts.
Logged current gear and when I select Reverse it flashes between 1 & 2.
Not Tried Yet:
Maxing out Trans Component Diagnostic Enable Temp and disabling the ISS.
**This is a requirment of the harness but I didnt have my computer with me, and didn't think that would keep it from completing the shift into reverse. Especially without ever driving the vehicle, would those codes be thrown? I've only read of these causing issues with auto shifting the forward gear and allowing full power...
BTW, the trans is a factory reman with 0 miles. But it was sitting in an old mans garage since early 2000's.