I have put a 5.3l with a 4l60e tranny in the car. How do I hook up the sensor from tranny to computer so the car knows what gear it's in. Please help

Should be a plug in the harness that came with it. Same plug that the computer uses to tell the trans what gear to go in. It's like 12 pins or so.

Yes but i do not know where it is. I'm trying to fix my car from some dude who messed it up

There are really two electrical systems related to "gears" on a 4L60E. One is range selection (PRND321) and the other is used for shifting. I believe that both are needed for proper operation of the transmission.

Third Gen F-Bodies didn't come from the factory with a computer controlled automatic transmission. If you have that engine/trans combo in a 3rd Gen you won't find the harness. Unless you're using an aftermarket transmission controller.

Not sure if this helps but I have the computer that was in the same truck that the engine and tranny came out of.

The truck harness will have wiring for trans. to PCM.
What PCM is used and the wiring for the PRNDL switch will vary over the years.

http://lt1swap.com is a good resource.

Posting in the Engine Swap subforum for LTx and LSx swaps would be better than this one; no third gen had an on-trans. PRNDL switch.

Ty

I need to ask a question. I have a 89 rs, I just bought the car a week ago. I am putting a 383 in it and a 350 turbo transmission. I am doing away with the tbi set up. ( the wiring harness is trashed and I had this engine and trans ) will the speedometer still work? Its electric. and if not can i rewire it to make it work?

Yes. I kept all of my Gauges