Have an engine code 'p0720 output speed sensor' . My truck starts in 2nd gear, shifts hard to 3rd. No 1st or overdrive. I've replace the sensor twice thinking that was the problem, cleared the code, but it came back and didn't fix the shifting. Also tried a different transmission control module to no avail. Weird thing is.. When I remove the sensor all together, it doesn't shift at all. So at least I know the sensor is doing something.. Anyone have any ideas on what I should check next? . 2000 Dodge Dakota SLT quad cab. 4.7l v8.

 

Moving to the correct section.

 

P0720 - Low output speed sensor, rpm above 15mph.

Just to be clear, you replaced the sensor on the transmission, correct?

 

that's correct. replaced transmission sensor. when its unplugged, the truck doesnt shift at all. when plugged in, i have 2nd and a hard shift into 3rd. no 1st or overdrive. ruled out the rear speed sensor because speedometer still works with the transmission sensor unplugged. wondering what else to check. relays and fuses are good.

 

What brand sensor is it? There have been lots of bad aftermarket sensors lately.

You may need to test the signal from the speed sensor - that's an oscilloscope.

 

Got it from Arnold motor supply. Oem replacement. Speed sensor works because my speedometer works

 

The speedometer signal comes from the rear differential speed sensor.

 

yep. speedometer works fine. i replaced the sensor on the transmission.

 

anyone have any ideas?

 

There are two speed sensors on the 45RFE, did you change the right one?