[dogster]

The speedometer on my '92 has a problem. The orange speed needle jumps all over the place, then suddenly returns to normal. It sometimes stops completely, and the next time I drive, it's ok.
I have already replaced the small speed sensor, at the rear of the automatic transmission, but it didn't help. When the speedometer stops working, so does the odometer so this tells me that it probably isn't the guage,
I was thinking it could be the two thin wires leading to the sensor, but why would it start working again if the wires were broken. Could it be the plastic gear mechanism in the tranny. The tranny was replaced about four years ago.
This problem has been happening for about a year, but it is getting worse. Has anyone had the same experience? All help appreciated.

 

[gear jammer 91"]

My speedometer used to do that. I found that I had a short in the wires for the speed sensor at the plug. I also replaced the gear reduction unit that screws onto the transfer case.

 

[coma700]

might be moisture getting into your plug too like if it rains or something, then when it dries it works again. i put dielectric grease in mine but its still giving me some trouble so i need to check my grounds and see if thats the problem.

 

[Philip]

With the age of the truck and the poor means of securing the harness that Dodge did. I would be looking the wires over real close to see if one has rubbed threw the insulation and is going to gound.

My $X$ did that a few years back.

 

[dogster]

Philip, did you ever fix the problem? I just finished taking the plug that goes to the sensor apart, and tested the wiring, but unfortunately , it is not the problem. I feel that it's wire related, possibly the harness that goes to the cab. Thanks for the replies.

 

[Philip]

I fixed mine the first time it acted up. I had to drive 65 miles without CC because the speedo was bouncing from one stop to the other.

I found one wire had been cut almost threw at the tailhousing of the trans. There is a wire clip to hold the harness. The harness had moved on the sharp edge of the tail housing.

 

[spanky660]

speedo

I had the same problem fixed the plug on trans. The speed works now ,but odo don't work . I noticed a ecm box on driver side behind battery can you check the plug there.:shock:

 

[r.messer51192]

I know this is an old thread, but my speedo issue is a little different.

Speedometer is stuck at ~40mph, but Odometer and Trip Meter both work fine. Needle starts to move up after ~50 mph, but still not the correct speed.

any help here would be great