Have the front band adjusted.

 

I have a similar situation going on with my 1999 Dodge Ram v8 360 2 wheel drive.

I replaced the speed sensor near the transmission on drivers side and I still get check engine and the speedometer still does not work. (its stays at 120 MPH) I do not have a break light issue however.

What else could be wrong to cause the speedometer not to work at all? Also the mileage counter is no longer working as it's stuck on the same number. Could this be a related issue?

 

On the 99, rear wheel speed sensor does the trans and odometer. (on the rear diff.) Not sure if that's your problem though..... as usually the speedo just doesn't do anything at all when the sensor goes bad....

 

I've seen plenty of times where the sensor on the rear diff screws up the speedo with no ABS lite.

 

1999 Ram 5.2L 4x4 here, 140K miles. Just got a p0720 code and did a Google search and found this forum.

I've done most of my own light/medium mechanic work for 30 years, but this truck is new to me. Looks pretty simple to replace the output speedometer sensor.

But I have a couple questions. First, a couple symptoms. When I accelerate, my inside vents kick over to defrost, and when I take my foot off the gas, there's a slight popping sound (single pop) and the vents kick in again. Also, just after it threw the p0720 code, when in cruise it will occasionally bump up about 200 rpms for a second and then come back down to cruising speed. Sometimes it does this two or three times.

BTW, fluid and filter were fresh last year, about 10,000 miles ago. I have ABS but the ABS light is not on. No other lights are on, and p0720 is the only code being thrown.

So:

1. Is the p0720 code always the output speedometer sensor?
2. Would a faulty sensor be causing the goofy switch between vents and defrost upon acceleration?
3. Do I expect to lose some tranny fluid when I pull the old sensor?

Thanks for any help.

 

I just changed my output speed sensor yesterday, my truck was throwing a PO720 code as well, also CEL was on. Pulled sensor and a few oz of fluid came out, just buy a quart of ATF+3 to top off. Turns out my old sensor was gummed up pretty good from tranny fluid. I bought a new one and threw it in and I will keep the old one for a backup. Do it when the truck is cooled down, Trans fluid is hot. Unplug battery nagative cable before starting.

 

Let's see, you have a 1999 so the speed sensor is in the rear differential. Check the wiring to it for any fraying or cuts etc. A few people have replaced theirs and the code goes away. Lots of other threads about related issues, just search for them.

The sensor has no relation to your 2nd issue. Search for "wild vents" and "heater treater".

Tranny fluid is not related to the speed sensor in the rear differential.

Hope that helps you some.

 

Statements earlier in this same thread indicate the output speed sensor is on the transmission, not the rear differential, in the '99. And according to my service manual and my eyes, the sensor is in fact there on my transmission, unless I'm looking at as different sensor.

Here's what my service manual says for the 1999 46RE:

DESCRIPTION The speed sensor (Fig. 231) is located in the overdrive gear case. The sensor is positioned over the park gear and monitors transmission output shaft rotating speed.
Fig. 231 Transmission Output Speed Sensor 1 - TRANSMISSION OUTPUT SHAFT SPEED SENSOR 2 - SEAL

Thanks for the info on the wild vents and heater treater. I'll get busy tracking down those threads.

 

I have a 1998 Ram 2500. I have been checking the Hayes manual, did google pic searches. Not helping. I have not worked on anything but the battery, alternator and starter, so all these terms are confusing me. Can someone take a pic, or maybe dumb it down big time for me? I just can't find it!

Thanks in advance.

 

It's on top of the rear end