I am a new member and am looking forrward to using this site and hopefully maybe able to contribute.I have a 1999 Durango, 5.9, 46re tranny, 4 wheel drive 137,00 miles. I have been having a problem with erratic shifts. A po720 code. I researched this forum and read that it might be the speed sensor. I replaced this, and saw no change. Still had the po720 code.Does anyone know what I should check next. I am reluctant to go to a local tranny shop, because most of these in my area are strictly change artists, and never try and just fix the problem. Thanks for any advice you might have to help with this.Ron

 

I am pretty sure that code is for trans/transfer case output speed sensor. I'm not at work so I don't have access to Mitchells. Should be on the drivers side rear of the transmission or transfer case. A 1 inch nut size plastic screw in sensor.

 

did you clear the CEL code manually? you need to remove the battery neg cable and hold the key to start for 30 sec or so, that should clear the light, if it comes back on once you start driving it let us know, but unless you clear the code yourself it will stay there for a while after you replace the sensor.

also yes magnum it is the output speed sensor on the tranny tailshaft.

 

Yes I allready changed the speed sensor on the tranny. I was wondering if the speed sensor on the differential might have to be replaced also. Thanks for the quick reply.
Ron

 

Thanks for the quick reply. Yes I did clear the code with my scanner, but when I drove it, it came back on. Any other ideas.
Ron

 

the two sensors do tend to go bad together i would replace them in pairs

 

Ron
Do you have a scanner that can read the transmission output sensor when driving? And when you replace the sensor, was there a lot debris on the end of the sensor?

 

yes my sensor will read while driving. I tried that and the code comes back on the minute I start to drive. I didnt see any large debris on the magnet, just quit a bit of fine metal.
Ron

 

Check to two wirs going into the sensor, one of them maybe just starting to break and causes you to loose contact.

 

I checked the wire, and they were bare clear into the fitting. Do you know where to buy a new wire with the right end. I dont have enough room to splice onto the old fitting.

Thanks
Ron