Back on the speedo issue again...
Here is the details I have gotten so far:
Speedo doesn't start moving till I am going 8-10mph then it starts moving from 0 up...no matter what speed I am going the speedo reads 10mph off(so 25 reads 15, 35 reads 25 etc)
I went and talked to my mechanic and he said the parts are $50 and would take mabey 45 min total to do both on my own. But do I need to replace both? Or mabey just one?
I dont have any lights on btw, so the common brake/abs light issue dosen't apply here...

 

It is likely that the sensor located in the center and on the top of the rear axle is bad. Replace it.

As far as your question, you asked if you need to replace "both" but didn't reference multiples of anything. The post is poorly written in that regards so I have no idea what "both" is in reference too.

The speedo issue is the single sensor on the rear axle as I have referred to.

HTH,

IndyDurango

 

+1

Most likely it is the sensor on top of the differential the (rear ABS sensor), but it also could be the transmission output sensor located on the drivers side mid way down. I would first replace the rear sensor. https://dodgeforum.com/forum/1st-gen...ensor-diy.html

 

A good scan tool will read both sensors, The last one that I had at the shop that had those symptoms, the one on the output of the trans or transfer case if 4X4 was bad.

 

When I said both, I meant both speed sensors...so the one in the transmission and rear diff.
So I got two different answers...lol. Damn!
Sweet right up on the sensor that Hydra!
What are symptoms that the transmisson sensor are going out?
Should I get a sensor,(for he rear diff) with or with out the wires?

 

replace the wiring harness as well when you replace the rear sensor. I had the common light issue though and i had replaced the sensor still had it replaced the little harness thingy and no issues. I know it's not the same issue but replace the sensor and the harness and see what that does for you.

 

See the rear diff sensor controls the 0-20 mph speedo, but it also controls the ABS. Also it corresponds in the PCM to help control the transmission and ensure correct shifting.

The transmission output sensor controls the shifting points of the transmission, but it also controls the speedo 20+ mph, and has ABS input. Harsh shifting, early, and late shifting are indications of a failing transmission output sensor.

Now here is the kicker!

They work on the same circuit, so when one goes out the other is usually right behind it, if not part of the problem as well. So in my honest opinion you should just replace both and be safe, however if you only want to replace what we think is broken then first replace the rear ABS sensor on the differential. There are 3 types of the same sensor available, so to answer your question I would need to know which one you are looking at.

ABS Sensor:
1. Just the sensor.
2. Sensor and small extension with harness.
3. Sensor and small extension with harness, and the entire length wires all the way to the front.


Classic example of this; My transmission (which is the same type housing as yours) output sensor went out on my truck, so I tested it to confirm and it was completely open. Then I tested the output sensor and it was also open, so it was bad. See when one of them went out it took the other out and so I had to replace both of the sensors.

 

At the moment my parts store only has,(for the rear diff) both the sensor and wires that connect right to it(mabey 3" or so) and the sensor for the trans(which looks like a therm plug to me but the part number matches) both together are $57 after tax so its not really a deal breaker if I have to do both I was just seeing if it was over kill or just a good idea really.

 

Few bucks now or big bucks later.

 

I would first replace the rear diff sensor then turn the ignition on and see if the ABS light goes out and if the speedo now works just for reference, but I would just go ahead and install the trans sensor after regardless. It's always better to replace them in pairs anyway.