No, not the bathing suit.

On a long drive across the country my speedo and odometer died on me. It happens over a great distance, like a few hundred miles. At first, the speedo would not read speeds of over ~60 mph, then it went to 50, then it just stopped working all together. Now no matter what speed i go the needek doesn't even twitch. Any idea what i should check?

 

Does the ABS light come on when it happens?

The ABS sensor in the rear controls the Speedo signal.

 

No, I'm pretty sure it doesn't have ABS. I know it has the light for it because it comes on when i first start the car, but i know i've locked up the wheels a few times. Maybe that's the problem...

 

Maybe the Rear Differential sensor is bad.

 

How would i go about checking it?

 

Usually you can get a Reading with an OHM meter with the Car up in the air safely.

If you get a reading spinning the tires it should be fine. If you don't get a reading then it is bad.
Also check the wires good known to break.

 

same thing happened to me i just went to the junk yard and pulled one off another volvo (carful not to strip the allen bolt) and popped it in mine and it worked like a charm. But my cruise control didnt work so i think that might be the switch itself!

 

Ok, i'll be sure to check it, where is it located?

 

On the back of the rear differential it has a wire coming from a small sensor, about one square inch. It has one Allen wrench bolt (again be careful not to strip it) and that’s just pull it out disconnect the wires and put in the one from the junk yard. I couldn’t find anyplace that sold it new! Good luck!