Hey guys, I recently bought a 2007 silverado HD 6.0 with 80,000 miles on it, transmission was rebuilt 10,000 miles ago because the truck sat too long and started to leak so a rebuild was done when it was out (with receipts) also confirmed with a carfax report, but something seems off with the lockup. Maybe it’s me, maybe not.

Truck shifts beautifully, but when it I am still gradually accelerating say up hill and am about 55 mph (maybe 20-25% engine load), the converter will sometimes lock, then unlock, then lock again. I know it’s the converter because it’s only like a 200rpm ish change at about 20-25% load.

I was careful to make sure it wasn’t a slip, I throttled into it when it unlocked and it was bitting, so I’m not really sure if this is an issue or not? It locks up and stays locked up on the highway. I looked into the brake switch issue that may cause this, but wanted to get some opinions before I throw needless parts at it.

Thanks!