Been swapping transmissions in my 99, the new transmission came out of an 01 or an 02 I can't remember for sure. My problem is that it won't start in park you have to shift it down into neutral and the other problems is that it the over drive won't kick in the light will stay on and the transmission temp warning is on also some have any advice? It shifts fine from 1st to drive as well.

 

you might have two separate issues, one of them being the neutral safety switch since it will start in neutral but not park. I'm not sure what might be causing the other issue.

 

you have a shorted wiring harness in the trans, drop the pan and take a good look at the location of the bottom of the shift pack solenoids, the wires get very hard from the hot fluid and break right at the temp sensor connector, will not shift to over drive because it thinks it is over temp, also the neutral safety switch can be readjusted to correct the no start in park, just loosen the bolts and with the key not running watch the light for "park" when it lights, snug up the bolts