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Test SD: Speedometer Jumps Up & Down Erratically

  1. Check Vehicle Speed Sensor Drive Gear

    Remove Vehicle Speed Sensor (VSS) from transmission. Ensure all gear teeth are in good condition, retainer clip is installed correctly and drive gear does not slip on shaft. If all are okay, go to next step. If problem exists, replace gear(s) and/or retainer clip as required.

  2. Check Wiring To Vehicle Speed Sensor

    Disconnect VSS harness connector. Using DVOM, backprobe between VSS harness connector terminals to measure resistance. If reading is greater than 500 ohms, go to next step. If reading is less than 500 ohms, repair speed control wiring circuit 150 (Dark Green/White wire) for intermittent shorts or opens. Recheck speedometer operation.

  3. Check Vehicle Speed Sensor Resistance

    Using DVOM, backprobe between VSS connector terminals to measure resistance. If reading is 200-230 ohms, go to next step. If reading is not 200-230 ohms, replace VSS. Recheck speedometer operation.

  4. Check Wiring To Cluster

    Reconnect VSS harness connector. Remove Electronic Instrument Cluster (EIC). See ELECTRONIC INSTRUMENT CLUSTER  under REMOVAL & INSTALLATION. Using DVOM, check for intermittent resistance between EIC connector "B" terminals No. 12 circuit 150 (Dark Green/White wire) and No. 8 circuit 359 (Black/White wire). See Figure . If circuit is okay, replace EIC. If intermittent resistance is found, repair wiring from EIC to VSS circuit 150 (Dark Green/White wire). Recheck speedometer operation.
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