Sometimes when I fire up my truck I have no speedometer. Of course when the speedometer doesn't work I have no overdrive. More often than not the speedometer works just fine, and thus overdrive, but inevitably when I am about to embark on a 400 mile trip, I will have no speedo and no overdrive.

Is it simply the speedometer cable, or is there an electronic problem. Is there any way to make overdrive work without the speedometer? (i.e. mechanically)

 

Both the speedo and the overdrive are electronic. I believe both are ran by the computer and I know their is no way to control overdrive mechanically. I would check the connector at the back of the trans/transfer case and make sure you are getting a good connection. Look over the wiring and make sure something obvious hasnt happened (ripped, chaffed things of this nature) I would have to have a wiring diagram to lead you further.

 

thanks for the reply. so there is no speedo cable? figures that the only thing that is electronic on the truck does not work.

 

Might try to replace the vehicle speed sensor located on your tranny output. If it wasn't a intermittent problem the sensor should fix it. If it worked and then quit after a while then worked again I'd put my money on a loose connection or short in the wiring somewhere. Jethrro

 

I think I have it solved, but only time will tell. The sensor on the tailshaft was loose as a goose. I tightened the nut and checked the connection.