I have a 1998 4wd automatic 12v 2500. The person I got it from had swapped axles and put some from a 2013 truck. The problem is the speed sensor doesn't work. I would appreciate any insight as to how to make this work. Thanks.

 

Speedometer should gets its clue from the rear wheel speed sensor. Originally, there was only one, on the rear pig. Does the newer axle have just one? Or two?

 

If the truck is rear wheel ABS there would only be one speed sensor at the rear differential. The 2013 trucks have sensors on each wheel so that won't work. Even if you hook up one of the wheel speed sensors the number of pulses is going to be different which causes the speedo to be way off. There are electronic speedo correction modules which may be able to make this work but no personal experience.

 

I swapped a later model 2nd gen disc brake Dana 60 rear over to replace my drum brake Dana 60 rear on my '96 Dodge Ram 2500. I found that the speed sensor mounted on the new disc brake rear had a different connector than the sensor for the '96 drum brake rear. Is it possible to swap the speed sensor on your rear to the sensor that was on your old 1998 rear? When I noticed this difference, I just went out and purchased a new sensor that was listed for '96 for the newer rear and it worked just fine.

 

The new axle does have two sensors, one at each wheel. I did try hooking up the one to harness connector that went to previous sensor and the ABS light turns off but it doesn't read the speed. I even tried hooking that connector to the transmission output sensor and from there it reads but the numbers are way off.

 

Gonna have to get some flavor of converter, tap off the sensor in the trans, and convert it to something the PCM understands.

 

Hmm, I had looked at some but none i looked were able to so i gave up. I will look into it again.

 

I have a friend who has a 97 and the speed sensor is on the transfer case. Will ECM on 98 read the pulse from a 97 speed sensor? If so, I can maybe drill and tap the port on the transfer case and install a 97 sensor there.

 

No. That sensor went away in 98, and the way EVERYTHING worked in the dash changed. It's completely different from 97 to 98, nothing will change over.

Might be easier just to get the correct axle to toss under there. Something with the sensor in the right spot.

 

Problem solved!
A friend of mine recommended I try a "Universal Speedometer and Tachometer Signal Interface" from Dakota Digital. I could get the sensor near the wheels to work, but by using one on the transmission and spending a couple hours trying different configurations I was able to get consistent readings. Then with a helper and a GPS I was able to adjust in on the road to get accurate readings.
Thanks to everyone for their help. Dertruck- you were right, thanks.