LEMON Manuals: Even more car manuals for everyone
Home >> GMC >> 1998 >> C3500 HD 6.5 F, Standard >> Repair and Diagnosis >> Accessories & Equipment >> Gauges & Instrument Panels >> Testing & Diagnosis >> Speedometer & Odometer Test >> Speedometer/Odometer Inaccurate

Speedometer/Odometer Inaccurate

  1. Ensure Vehicle Control Module (VCM - gasoline engine) or vehicle speed sensor buffer (diesel engine) is correctly calibrated for axle ratio and tire size. If axle ratio and tire size are okay, test drive vehicle over a known distance of at least 5 miles. Using scan tool, compare scan tool displayed vehicle speed to speedometer. Record initial and final odometer readings and actual distance driven.
  2. If scan tool and speedometer are within 4 MPH of each other, speedometer accuracy is within specification. Go to next step. If scan tool and speedometer are not within 4 MPH of each other, replace instrument cluster.
  3. Divide actual distance driven by indicated distance driven. If calculated result is .96-1.04, odometer accuracy is within specification. If calculated result is not .96-1.04, replace instrument cluster.
    NOTE: Before performing following test, ensure no problems exist in vehicle speed sensor, vehicle speed sensor buffer (diesel), or Vehicle Control Module (VCM - gasoline). See SYSTEM/COMPONENT TESTS article in ENGINE PERFORMANCE section. See ANTI-LOCK article in BRAKES section.
scientia non olet · About LEMON Manuals