HELP speedo bouncing!!!

[gotV10]

from time to time my speedo is bouncing up and down in a 2000 rt/10. there doesn't seem to be any one condition that triggers it. it does it both while driving and while sitting in traffic. as a side note i recently replaced my stock pcm with a 1996, new from roe. the problem never existed prior to replacement. not saying that the pcm caused it just for everyones info. the speed sensor was tested and showed no problems, and we hooked up to the computer and it was reading accurate constant speeds. has anyone experianced speedo head failure, or does anyone have any other ideas. also the battery has already been replaced, that was my first thought. if anyone might think that it is the speedo head, approx cost to replace?
thanks in advance for the help you guy always seem to have the right answers....ever considered marriage advice, HaHa...or is there ever a right answer there?
Thanks again,
Ryan

 

[Bill B]

Could be a bad spedo sending unit on the transmission.

 

[viper spray]

HELP speedo bouncing!!!

Get regular bathing trunks!

 

[95Viper]

I had the same problem on a 95. Tested a billion things from good tips from members. Tried a lot of ground wires. I have a PCM and ICM next to each other, I believe this might have been combined in later years. My ICM wasn't processing the speedo signal correctly. Swapped it out and it has been perfect since.

The Viper Tech went through a relatively simple diagnostic test spelled out exactly in the Service Manual to find it out.

My siggestion is to swap back to other PCM and see if it affects it.

 

[XS TORQ]

I was having a problem w/ mine, and (maybe coincidence) after disconnecting my battery for an unrelated issues, I haven't seen it since.

 

[JGK95]

Battery or Altinator needs testing. Learned first hand in my non Dodge car that either the battery is near term or the alternator isn't recharging the battery in which case the alternator is ready for a replacement/rebuild.

Jay K.

 

[Dimitrios]

mine does it as well from time to time but only on start ups.

 

[99 R/T 10]

Hey Dimitrios,
Do you have O2 sims in the rear?