Hi,
I did a search for this butI didn't really get a good answer to my question. I have a 5.9L 1998 Dodge Ram 1500 4x2 and the other day the CEL came on so I took it to Autozone and got the following codes: P0351 and P0720. The firstone is the ignition coil and the second is the VSS. I cleared the code and as soon as I accelerated, it hung in 2nd gear a little too long, the CEL came on, and then it shifted. However, it didn't shift like that afterthe CELfirst came on. After searching these forums, I don't beleive it is the Wheel Speed Sensor in the differentialsince the ABS and Parking Brake lights did not come on and there are no speedometer issues.

I have the Haynes manual, but thepictures it shows look nothing like the one on my transmission extension housing. The one on my housing has a two wire lead which disconnects and it looks like the sensor (which is set in a plastic nut)is removed with a socket wrench . There are no screws as is shown in the Haynes manual. This is the only wire going into the transmission extension housing. When I pull up parts online I get pictures of the part with screws on it.

Has anyone replaced this? Does any of this sound familiar?

 

P0720 is the VSS on the tranny. You can reset the CEL and it will pop back on at 15 mph.

 

the sensor you are looking at in the Haynes is the VSS in the Transfercase of a 4x4
4x4 have both the sensor you have plus the sensor in the photos
it is so the speedo shows the right speed in 4x4 low

In your case...........

First i would remove the VSS that you have in your trans
catch the fluid that drips out into a gallon milk jug or something similar
clean the metal shavings off the sensor (happens because the sensor is magnetic)and reinstall

that is what i did and it helped with my problems (I had 3 mm's of shavings on it!) yeah...wow

if doing this doesn't help replace the sensor

 

oh-ya forgot

add the fluid that dripped out back to the transmission, through the dipstick tube

go ahead and replace the fluid and filter if you haven't lately

For the 4x4 owner's reading this, the transfer case VSS is not magnetic

 

Didn't even know I HAD a VSS on the xfer case.

When I changed out the VSS on the tranny ... no fluid came out. I was prepared though ... waste of paper towels.

 

Well I found a copy of the 2001 Service Manual and in the 46RE tranny section it shows a picture of what my sensor looks like. I also found that it is to be torqued at 20 ft-lbs.
It is a nylon screw insert on mine so I don't think it is magnetic.
I'll pick it up at the dealer since I can't find that particular part online for some reason.

 

hey, it is plastic or nylonor whatever...they always are (i have never seen a metal one),

the magnetic part is inside the tipof it (covered with the nylon),
yours is magnetic because there is no other way for it to sense the speed (the transfer case VSS uses a gear and shaft)

 

lmao
i am in school right now (i am only 17)
needto be working on an essay

so......did you take the VSS out?

 

that sensor on the tranny is not the VSS it is the output shaft speed sensor. I cant speak for the 4x4's since mine is 2wd but P0720 is "output speed sensor malfunction". i had to replace mine about 6 months ago it is near the rear of the tranny on the drivers side. it was $35 at napa. when i changed it mine had a nice amount of shavings on it.

 

Well.....only part right

It is used as both a VSS and a output shaft speed sensor

The signals are used by both the transmission control module and the powertrain control module (PCM)
It basically tells your speed to the speed through the PCM and controls the transmission

This is from the manual that Steve00ram360 posted a while back

"Speed sensor signals are triggered by the park

gear lugs as they rotate past the sensor pickup face.

Input signals from the sensor are sent to the transmission

control module for processing. Signals from

this sensor are shared with the powertrain control

module."