My 1998 DOHC R/T MT has an erratic speedometer problem. As this occurs you can tell the fuel is being cut off as the car dies and reignites. I am not thinking cluster panel because at that point isn't the panel simply getting inputs for the display of speed? My problem is obviously effecting the running of my engine. I was so convinced the speedometer sensor that plugs into the top of the transmission housing was the problem I actually tried two new ones with no luck. Am i down to the engine computer or wiring? My understanding is that some engine control utilizes inputs from the Speed sensor and not much else is left in the loop. Would appreciate any help from the experts here. Thanks.

 

almost seems as if some of the wireing is bad if you tried new a new VSS sounds like its time to start tracing wires.

 

my wifes neon did the exact same thing - turned out to be a bad cell in the battery - would hold enough charge to crank and run but made the alt overcharge @ like 16volts

When tested - battery tested bad and alt tested bad

When battery replaced - alt tested good @ 13.5 volts

All symptoms went away.

Hope this is your problem as it was a real easy fix for me

 

That is very interesting. My problem instantly went away yesterday after replacing my motor mounts. Driving into the garage the speedometer was jumpy or dead. Did the engine mounts and the speedometer is running perfect. Now the engine mounts did require some up and down jacking of the engine with a block of wood under the oil pan area. And the driver side transmission mount under/behind battery area required taking the battery out and the under hood fuse box out. So I moved the engine a little, moved a lot of wiring around, and disconnected and reconnected the battery. Very strange problem with a mystery fix. But yes I believe both replies here are in the ball park. It must be something to do with wiring or the battery. Thanks for the input. I'm just keeping my fingers crossed at this point.