FixVault
Home › GMC › 1996 › Forward Control 4.3 W › Repair and Diagnosis › Electrical › Gauges › Instrument Panel - Gasoline › Testing › Speedometer/Odometer › Speedometer/Odometer Inaccurate (Van)

Speedometer/Odometer Inaccurate (Van)

  1. Ensure Vehicle Control Module (VCM - gasoline) are correctly calibrated for axle ratio and tire size. If problem is still present, go to next step.
  2. Connect scan tool and monitor vehicle speed. Perform a test drive of at least 5 miles at 50-65 MPH. Compare scan tool speed to speedometer speed. Record initial and final odometer reading and actual distance driven. If scan tool and speedometer indications are within 4 MPH of each other, speedometer accuracy is within specification. Go to next step. If scan tool and speedometer indications are not within 4 MPH of each other, replace instrument cluster.
  3. Drive an actual distance according to scan tool as opposed to distance indicated by odometer. If indicated ratio is .96-1.04, odometer accuracy is within specification. If indicated ratio is not .96-1.04, replace instrument cluster.
About FixVault