i bought a 1991 W350 cummins automatic and the speedometer works but the odometer doesnt. is there anyway to fix it besides replace the dash cluster? also the wait to start light never comes on but it always fires right up any suggestions?

 

I had that happen to my 97. I bought a used dash cluster from ebay and swapped out the speedometer. It was an easy and cheap fix for me.

 

With the wait to start light, are you grid heaters working? You can tell by seeing whether the voltage drops down to around 8V for a few seconds when you turn the key to the run position and it is below 60F. If the voltage isn't dropping down, something is causing the entire system not to work. If the grids are working, then you just have a problem with the light.

I don't know how the odometer works on a '91 so I can't help you there, sorry.