I have a 1999 Ford Ranger, 4 cylinder, 5 speed, 2WD truck. When I started it up today, I noticed that the ABS light came on. Also, I noticed that the speedometer was acting erratic; will not register till I get around 35 MPH. At that speed the speedometer will jump between 0 and 25 MPH then be steady at 35 MPH and above. Once you slow down below 35 MPH, the speedo goes to zero. Both problems seemed to occur at the same time. Any suggestions troubleshooting?
Is this an electronic or mechanical speedo? If mechanical, it sounds like a bad cable or possibly a broken gear at one end or the other. If electronic, the Vehicle Speed Sensor (VSS) is suspect, though it could be the speedo itself, the ABS may take signal from the VSS and that suggests it as a single point cause.