How do you test to see if your speedo is shot on a 93 D350??
 

My OD and speedo is not working. I replaced the vss ($55) and am lost now. How can I test the speedo to see if it is the problem? Also where is the fuse panel on 93 D350?
Thanks in advance!!

also by the way the CC does not work as well

the speedo being bad will not cause the od to not work. The pcm not getting a signal from the vss will cause the od to not work. Check the charging system with a volt meter and make sure it is charging. You could have a bad crank sensor also that will cause your problem.

Thank you for your insight...I will chx that tomorrow, can you tell me what would cause both OD and speedo not to work..do you think they are two separate issues??
Thanks again

If not the charging system, it sure sounds like something in the VSS circuit. It's always a nice luxury to have a scanner so you can see if the VSS signal even registers in the PCM. Anyway, if you havent yet, you may want to focus on the thing on the transmission that the sensor screws on to. Pull it out and see if the gears inside still mesh, or if they are worn out. Have a good look at the VSS connector too, make sure the terminals aren't spread or corroded, and follow the wires up to the front, make sure they haven't been chafing on anything.