I've been looking for some information here as this forum has helped me out many times before. I've got a 2005 ST that's auto, a 4.7L and 4x4 that recently the speedometer works intermitently. I'm throwing a P0501 code stating that there's something wrong with the vehicle speed sensor. Is the speed sensor located on the differential housing or is it located on the transmission? I've been told conflicting information on this and don't know what to try. Any help would be much appreciated.

 

There may be a speed sensor in the rear axle for the ABS brakes, but the speed sensor you are looking for should be on the transmission.

If you download the service manual from the FAQ section stickied in the 3rd gen dak section, information on how to remove the output speed sensor is on page 4403 of 5249. Looks like you will need a drain pain and some spare ATF+4 to top of the trans when you are done. This is all assuming you have the 545-rfe transmission.

 

The speed sensor on my '05 is on the rear diff. Because it's there, when I switched to 4.10 gears, the speedo showed the correct speed without having to change anything and without recalibrating it or changing the setting with my SC tuner.

 

Thanks everyone for the help. I was looking into the speed sensors on the transmission. There are two: one is for input and the other is for output. I'm going to pick up the output sensor as I'm assuming this is the one that's gone bad. Looks like the input and output part numbers are the same. Maybe I'll do both while I'm under there.

 

I wanted to post an update to this thread as I did find the problem. It was not the speed sensor on the diff housing or the input/output sensors on the transmission. It was the actual ABS module itself. After replacing all these sensors with no luck, I started troubleshooting the CAN-BUS system with a 4 channel scope. The input voltage to the speed sensor would show correctly when I first started the vehicle. After it ran for a few seconds, the voltage would go through the roof. A good friend was able to use an old dodge diagnostic tool to check the PCM, and it was working fine. I did some more tests with the ABS module and decided I'd replace it with a used unit. I found one from a reputable scrap yard for $85. Took about 45 minutes to install and the speedo works again plus the ABS light is out. Luckily, this module must have had the right correction factor in it because my speedometer readings are correct. The biggest pain was to bleed the brake system correctly. To prime an ABS unit, you need the STAR system (or you're suppose to use one). I got around this my doing a bunch of emergency stops to force it to kick in, then rebled the brakes.