Itbgoes from driving completely fine to nothing in a sec. No slipping not even trying to grab, and no warning. Then I can go and drive it a few hours later. I changed the fluid the firstbtime itbhappened and that seemed to work then it happened again and looked at the fluid and it's oil color after 2 weeks. No check engin light, no codes. It's not the brake lit weird thing, and I'm wondering if it's hydraulic pressure or solenoids or if i need a new tran how to in swap it or can someone point me to directions to do so without any hoists or lifts as I dontbhave any. Also I have no knowledge of cars so please be clear with your response

I only know what I've read on here today
Thanks so much for any and all help