I've done all sorts or research into this and I have replaced both my NSS and output speed sensor. But the codes still there. Everywhere I look people have replaced the NSS and it all works out. but mine still isn't. Any ideas?

 

Cheap code readers read all 7** codes as 700. They are all auto transmission codes.
Try better code reader to get actual code.

 

First of all, how's your trans shifting/down shifting? As Rockville suggested recheck for additional codes, PO700 is a generic trans code that is usually associated with another specific code.

One or more of your shift solenoids may be out of range (11-15 ohms) that is throwing a code. You can check the resistance of the 1-2 and 3-4 shift solenoids through the gray connector (passenger side at the firewall).

Use a digital meter grounded at the battery. I believe the two male connectors on the left side of the connector (with the lock facing up) are for the shift solenoids. This doesn't eliminate the possibility that there is a problem with the wiring or connectors but if you get too much resistance through either one it will justify pulling the pan and checking the resistance directly at the solenoids.

 

Jeep shifts ok. Except won't go into overdrive ever. I've tried with three different engine readers and they all just say P0700

 

You need a better scan tool. P0700 is a code that sets in the ECM to turn on the check engine light and alert you to codes stored in the TCM.

P0700 is just telling you that the trans control module wants the check engine light on, nothing more, nothing less.

A problem with a shift solenoid will affect TWO gears. If you have an issue with only ONE gear, chances are you have an internal mechanical or hydraulic fault.

First step is to get a scan tool that can read codes/data from the TCM.

 

Too bad. I'd bet that a dealer with a DRB scanner would be able to narrow it down. If you don't want to drop the one-hour labor charge from a dealer then do the check through the connector like I suggested (10 minutes and free). They want the resistance to be 11-15 ohms but it looks like the cutoff for replacement is 20 ohms. There may, in fact, be other internal problems but I think it would be a good place to start and it can't hurt anything. My Actron 9140 will pull codes from the TCM...if you should happen to find one.