tmoore

Hi everyone, I bought a 91 250 4x4 with a NV 4500 tranny a few weeks ago and the speedometer is not working. I replaced the speed sensor on the drivers side of the transfer, the most common problem. I checked all the wireing going to the gage cluster. Everything had a good connection, at least that was visiable to me. My question is, are their problems with the speedometers thems selves? Does anyone have any other sujustions of where to go next? Thanks in advance.

Bushy

Hey, welcome to the ranch....

In my case I had similar problems...but the speedo did not fail to work outright... it just thrashed around. I replaced the speed sensor as you did and that cured my problems.
I'd suggest you pull the assembly out, and have a look at the square "socket" that is on the other end of the sensor assembly. It is driven by a small square drive rod/post in the tranny. If the socket is "rounded out" then you've found your problem. Next would be to look at the actual drive rod/post itself. Make sure it is in good condition.

Some of the guys here have had this problem and found a couple different fixes for this. Maybe they'd jump in here... in the mean time check out those things and get back in here with your results.
Pastor Bob....

frostie

I would first make sure the yoke on the transfer case is tight.
On first gens there is a ratio adapter, then a signal generator. If the drives look good as Bushy was saying then I would get a volt ohm meter. disconnect the adapter at the transfer case. hook the volt ohm meter to where the wires plug in and set the meter to measure HZ which is hertz. you should be able to spin the drive by hand and get a reading. If you get a reading then your problem is in the wiring or speedo itself. if there is no reading then your problem is in your hand. either the ratio adapter or signal generator.
I hope that makes sense

tmoore

Bushy, Frostie, Thanks for the info. I did pull the whole assembley off with I replaced the speed sensor, it all looked good and the gears seemed to be tight wasn't rounded out or anything like that. But I didn't go any further into it then that for lack of time. I was hoping the $40 speed sensor for be a quick and easy fix to the problem. I guess its time to bring out the volt meter. hopefully it will be in the speed generator then. Frostie you wouldn't happen to have a part number for that by any chance? I thank you guys again. I was just courious if anyone else had theis problem, so I wouldn't be at the wrong end. I hope thats it and not electrical, or in the speedometer itself.

Tyler

frostie

I dont have a part number. I have one still attached to an old getrag. I looked at it and saw no numbers on it. Im sure the local Dodge dealer can find it for you.
Good luck