So, I bought a 99 ram 1500 V8 5.2L and everything seemed fine except the check engine light was on. It gave me a code for the Output speed sensor(P0720) so i figured it was no big deal since the spedo still worked and it shifted fine. Then the abs and brake lights came on, so I replaced the abs/speed sensor on the rear diff. Then the truck began to stall randomly while driving and say "no bus". After about 5-10min it would start back up. One day it did it 5 times in a mile. So that night I changed the Output Speed Sensor on the back of the transmission, pulled the negative cable off for 5 min and reconnected. Not a half a mile down the road the CEL came back on and gave the same Output Speed Sensor code. A couple days later the truck seemed to loose power and would not shift out of 1st gear. Come to find out the cat had fallen apart and pieces were wedged in the exhaust pipe. I then cleaned out the cat and put it back on as I do not have the money to buy a new one right now. The truck continued to randomly stall so I found a used PCM out of a 99 ram 1500 and put it in. It seems to have fixed the stalling issue but I still get the same Speed Sensor code. All the gauges work and the truck runs fine but with the CEL on I can't get it inspected.

 

If you replaced the output shaft sensor with NEW, it would not be unheard of to get a defective unit.
I have seen parts like that where others have gone through four of them before getting one that was not defective.
Aside from that it is possible that there is a problem with the connector, or wires leading into the connector.
It would be worth the hassle to check out that section of harness pigtail.

 

Output speed sensor is on the side of the trans.......

 

Don't know if this will help you or not, But I had similar Issues with my 98 Durango. Shifting problems though and It died one time on me because of it. Same code for the same sensor. Check the plug and wiring for your sensor. I replace my sensor and it changed absolutely nothing. So I thought, maybe I have a bad sensor or some trash on it so it's not getting a good reading. So I got a mopar replacement for it instead. No change. Took it over to my dads house so we both worked on it. He figured it out. Transmission fluid and mud/water got on the wire and I guess it got hot enough that it disintegrated the coating on the wire and they were touching eachother and shorting out. But It was hard to tell because the wires had been exposed for so long, the copper wasnt shiny anymore. So that's just a thought. I pulled the pins, used some heat shrink wrap and put it back together. No more problems in two years.

 

Things like this is exactly why I gave him the first reply to the matter, that was along those lines. Whether they are cooked, abraded, or in some cases like the cause of an erratic taillamp functionality issue I had to figure out--corrosion set in behind the pins inside the plug where they can be visually confirmed without dismantling

 

Double Oh Dodge I completely agree. I have had many situations where it was a weird yet simple electrical issue and I always looked elsewhere first. This being one of them. We think the wire coating got soaked with trans fluid and then heat and the elements did the rest. Super simple fix though.