I have a 1995 Cummins motor and 1995 47re. (Yes it’s a 95 re it was one of the first off the assembly line.) Behind it is an np241 passenger drop out of a 90s dodge gasser. And the rear axle is a Dana 70. I have a speedometer I want to hook up but I’m having trouble figuring it out. The 47re has a 2 prong vss that’s plugged into my pcm. Tcase has a 3 prong vss that’s unplugged as of now. And rear end has a 2 prong sensor that’s unplugged but I believe it’s used for abs. My Speedo can take a square wave signal, magnetic pickup with 2 wires, or a Hall effect sensor. Just trying to find some guidance on making my Speedo work. Anything is appreciated.

 

Can you possibly provide some additional details regarding the speedo that you plan to use? A photo and it's input would also be helpful.

 

speedo

i think that link will work. It’s a speedway electric speedometer. I can send a pic of the diagram in the morning with some pics of the senders too if you’d like. I don’t care what sender I use. Which ever is easiest I guess. The wiring harness I have has a plug that’s supposed to go in the tcase but the different model 241 doesn’t have the same plug. But basically I know the Speedo says it can have 2 wires from a magnetic pickup. 1 wire for a square wave signal, or your standard Hall effect setup. I think the 47re sends a square wave signal but I’m not entirely sure on that.

 

According to the link it "may" not fit. What is wrong with the stock speedometer?

 

Speedo on the older trucks gets its cue from the VSS in the tailhousing of the trans (2wd) or T-case (4wd.) Should be able to just plug it in, and it should work.

 

I guess what I’m looking for is some information on the sensors themselves. This is a drivetrain swap, it is sitting in a 1978 Chevy k30 and I redid the whole dash that’s why I’m using this gauge. I figure one of the three vss on the drivetrain would do the trick. But like the vss in the tcase has 3 prongs and I’m assuming one is a sensor ground, one a signal, and one like a 5v supply but I don’t really know, and I don’t know what signal it sends. I don’t know what type of signal any of the vss send.

 

Tone ring and hall effect, so, square wave?

Yep, one wire is 5 volt feed, one wire is signal return to the PCM, third wire is ground.

 

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The gauge you linked is a stand alone unit so it may be different from what the factory used.
Found some info you may want to look over. They do offer a GPS sender for that gauge.

 

i didn’t end up feeling like running a 5v supply to the tcase so I spliced into the output shaft speed sensor in the 47re tailhousing. Each end of the magnetic sender to the gauge and it works. It seems a wee bit off and I can’t find anything online to what ppm the sender makes so unless any of y’all know, the gauge has a manual calibration I can run a fixed mile track and get it dialed in. But it does work, you can run a Speedo off the output shaft speed sensor in a 4wd 47re. I answered one question at least.