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Test SB, Speedometer Reads 0 MPH At All Speeds With Vehicle In Motion

  1. Verifying Prove-Out Mode: Turn ignition on. Ensure all display segments come on, momentarily turn off and return to normal operation. This is prove-out mode. If all segments do not operate correctly in prove-out mode, replace instrument cluster. Install door pillar sticker to indicate instrument cluster has been replaced. If all segments operate correctly, proceed to step 2).
  2. Checking Odometer: Ensure odometer advances when vehicle is driven forward. If odometer does not operate correctly, proceed to step 3). If odometer does respond properly replace instrument cluster. Install door pillar sticker to indicate instrument cluster has been replaced.
  3. Checking Speed Control (Cruise Control): On models without speed control, proceed to step 4). On models with speed control, ensure speed control operates correctly. If speed control operates correctly, proceed to step 9). If speed control does not operate correctly, proceed to step 4).
  4. Checking Speed Sensor Wiring: Disconnect wiring connector at speed sensor on transmission. Using ohmmeter, measure resistance between wires of wiring harness to speed sensor.
  5. Resistance should be greater than 500 ohms. If resistance is okay, proceed to step 6). If resistance is less than 500 ohms, check wiring between instrument cluster and speed sensor, speed control, and air suspension for defective circuit.
  6. Checking Speed Sensor Resistance: Using ohmmeter, check resistance between speed sensor terminals. Resistance should be 200-230 ohms. If resistance is within specifications, proceed to step 7). If resistance is not within specifications, replace speed sensor.
  7. Checking Driven Gear & Retainer Clip: Remove speed sensor from transmission. Ensure driven gear is in good condition, and driven gear retainer clip is installed. If components are defective, replace as necessary. If components are in good condition, proceed to step 8).
  8. Checking Drive Gear: Ensure drive gear on transmission output shaft is in good condition. Replace drive gear if defective. If drive gear is okay, proceed to step 9).
  9. Checking Wiring To Instrument Cluster: Reconnect speed sensor wiring connector. Disconnect negative battery cable. Remove instrument cluster. See INSTRUMENT CLUSTER R & I  .
  10. Using ohmmeter, check resistance between instrument cluster connector C2-2, pin No. 31 (Gray/Black or Yellow/Light Blue wire) and connector C2-1, pin No. 4 (Pink/Orange or Black/Light Blue wire). Resistance should be 160-230 ohms.
  11. If resistance is within specifications, replace instrument cluster. Install door pillar sticker to indicate instrument cluster has been replaced. If resistance is not within specifications, check connections and wiring circuit from instrument cluster to speed sensor. Repair wiring as necessary.
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