Please Help save my sanity:
95 V-6 Dakota 4x4 Tach started jumping around while driving and then the engine shut down. I have replaced the pick up coil, new distributor, rotor, battery, crank sensor, battery, fixed the 3to 1 splice under the ASD relay and still the tach is jumping around and sometimes the speedometer too. The battery is overcharging now and the check engine light came on with a code 46. I am afraid the engine is going to continue shutting down until I fix this tach problem

 

Check the speed sender unit, (AKA speed sensor) it's on the trans, drivers side, I had this problem on my '95, as soon as I replaced the sensor the problems disappeared, although I found out about mine the hard way, the clip the hold the wires away from the front drive shaft(or up out of sight) broke and the wires tangled around my front shaft and tore the wires out. When I repalced the sensor it took care of most of the wires, but I also broke a ground wire that I had to repair, prior to the tearing of the wires the speedo and tach bounced all over the place. I waited and waited and waited too long

 

code 46 - battery voltage to high.
sounds like the voltage regulator. that's controlled by the computer and the only way i know of to fix it is replace the computer.