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Speed Sensor Test

  1. Partially remove speedometer cluster so that access to the speed sensor is possible. See the appropriate SWITCHES, GAUGES & SPEEDOMETERS article in this section.
  2. Turn ignition and dash control switch to "ON-AUTO" position. Connect voltmeter between ground and terminal 2 (Black) on speed sensor 3-wire connector. Voltage should be between 9 and 11 volts. If higher or lower, replace control module.
  3. Connect voltmeter between ground and terminal 3 (Red) on sensor connector. Voltage should be 1 to 2 volts less than at terminal 2. This is the voltage drop through L.E.D.
  4. Connect voltmeter between ground and terminal 1 (Green) of sensor connector. Roll car forward (approximately 6 feet) while checking voltage. Two voltage peaks should occur in the distance the car travels.
  5. This is the photo transistor output. If voltages in these 2 tests do not meet specifications, replace the speed sensor.
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