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Scorpio (Speedometer Pointer Remains At Zero WithVehicle In Motion)

  1. Turn ignition switch to "RUN" position. Raise and support vehicle. Disconnect speed sensor wiring connector. Using a voltmeter, check for approximate battery voltage between pins No. 1 and 3 on harness side of sensor connector. See Fig 1 . If okay, go to next step. If not, check fuse No. 20. If fuse is okay, repair open in wiring between fuse No. 20 and speed sensor connector pin No. 3 or ground and speed sensor connector pin No. 1.
  2. Turn ignition switch to "OFF" position. Using an ohmmeter, check resistance between pins No. 2 and 1 of harness side of speed sensor connector. See Fig 1 . If resistance is 400-600 ohms, go to next step. If resistance is less than 400 ohms, go to step 6). If resistance is more than 600 ohms, go to step 9).
  3. Using jumper wires, jump pins No. 1, 2 and 3 of sensor side of speed sensor connector to same pins on harness side of sensor connector. Turn ignition switch to "RUN" position. Connect a voltmeter between pin No. 2 (positive lead) and pin No. 1 (negative lead) of harness side of speed sensor connector. Slowly rotate rear wheel and check voltage. Voltage should cycle to greater than 5.5 volts and decrease to less than 1.5 volts in at least 8 cycles. If okay, go to next step. If not, replace speed sensor.
  4. Turn ignition switch to "OFF" position. Disconnect 5-pin connector from back of speedometer. Using an ohmmeter, check for continuity between pin No. 1 and ground on harness side of connector. See Fig 1 . If continuity is present, go to next step. If not, repair open in speedometer ground wiring.
    Fig 1: Speed Sensor & Speedometer Connector Terminal Identification
    G102967Courtesy of FORD MOTOR CO.
  5. Turn ignition switch to "RUN" position. Using a voltmeter, check for battery voltage between pin No. 5 and ground on harness side of speedometer connector. If okay, replace speedometer assembly. If not, check fuse No. 22 or repair open in speedometer feed circuit.
  6. Disconnect harness connector from back of fuel computer. Repeat test in step 2). If resistance is less than 400 ohms, go to next step. If resistance is between 400-600 ohms, replace fuel computer.
  7. Disconnect speed control module wiring harness. Repeat test in step 2). If resistance is less than 400 ohms, go to next step. If resistance is between 400-600 ohms, replace speed control module.
  8. Disconnect 5-pin connector from back of speedometer assembly. Repeat test in step 2). If resistance is less than 10 ohms, repair short-to-ground in circuit between speed sensor and speedometer. If resistance is more than 10 ohms, replace speedometer assembly.
  9. Disconnect 5-pin connector from back of speedometer assembly. Using an ohmmeter with long leads, connect one lead to pin No. 2 of harness side of speed sensor connector and other lead to pin No. 4 of harness side of speedometer connector. If continuity is present, replace speedometer. If not, repair open in wiring between speed sensor and speedometer.
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