Had an issue a few weeks ago where I all of a sudden lost my speedo. Parked it for about a week, had no choice but to drive it for a couple days and out of nowhere it all of a sudden it’s in limp mode, won’t go into overdrive or 1st gear. Never missed a beat before the speedometer issue. Already replaced the speed sensor on the trans and the one in the rear diff. it’s a low mileage truck and my pride and joy. Any help would be great.

 

Did the speedo start working after you changed sensors?

 

It might be an issue with the wiring between the sensor and the ECM. I would verify that you don't have damage along the loom and that the connector is plugged in completely and cleanly.

 

I’ll take a look into the looms coming off the pcm for any damage. They looked fine at the sensors, but no the speedometer did not start working again even after the sensors were replaced.

 

Still no fix. New sensors, no wires corroded/broken. No loose pigtails in either the connectors on the sensors, connection at the pcm, or the connectors behind the cluster. I’m stumped. I’m leaning towards a possible pcm but was hoping I could maybe get another thing to look for here.

 

Do you have a scanner you can plug in, and see if the PCM is getting a signal from the sensor?

 

Yes I do. Had it plugged in for a short drive up and down the road. Not registering any mph on my scanner. I work at a dodge dealership so I’ll be swallowing my pride and bringing it in to use the dbr3 on it.

 

See if you are getting reference voltage back to the sensor.