Hi,

The speedo in my 96 Escort Si works when it wants too! Everythin else on the dashboard (revs, lights, odometer etc) works fine without a problem.

It'll usually work when it's not raining/cold etc if that helps? It'll just kick in all of a sudden and work perfectly until the car goes back to 0mph.

 

There are three parts to the speedometer. One, you've got the speedometer gear in the transaxle, this is the part that sticks up with a wiring connector on it and a cable in the center. This speedometer gear is held on with a metal c-clip and a bolt. Two, is the cable on the gear, this can be pulled out and checked. The metal cable inside the housing spins and transfers this spinning force to the speedometer. Three, the speedometer is a spining magnet that is surrounded by a thin metal housing. The most likely cause of the jumping is the cablehas broke internally. Remove the internalcable and check, if it's good then grease it and re-install. You could also have a stripped speedometer gear. You could have a rusted or worn out speedo gauge as well. It's a matter of checkingeach part or replacing all of them.