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Speedometer/Odometer Is Inaccurate

  1. Check that Vehicle Speed Sensor (gasoline engine) or Vehicle Speed Sensor Buffer (diesel engine) is calibrated correctly for axle ratio and tire size. If calibrations are correct, problem is resolved. If calibrations are not correct, go to next step.
  2. Connect a scan tool to monitor vehicle speed. Drive vehicle at 50-65 MPH over a known distance of at least 5 miles or more. Compare scan tool indicated speed with speedometer reading. Record odometer readings. If scan tool readings and speedometer readings are not within 4 MPH or each other, replace instrument cluster. See INSTRUMENT CLUSTER  under REMOVAL & INSTALLATION. If scan tool and speedometer readings are within 4 MPH of each other, speedometer accuracy is within tolerance, go to next step.
  3. Divide the actual distance driven by the distance shown on the odometer. If the indicated ratio is between .96-1.04 miles, odometer is within tolerance. System if okay. If distance is less than .96 miles, or more than 1.04 miles, replace instrument cluster. See INSTRUMENT CLUSTER  under REMOVAL & INSTALLATION.
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