To disconnect a manual odometer, pull the speedometer cable, which shuts down both devices. Digital odometers are disconnected by either direct, serial or diagnostic methods. For the direct method, dismantle the dashboard and take apart the odometer. Remove the chip, and attach a cable directly to it for reprogramming. Once finished, reinstall the chip, odometer and dashboard.
To use the serial method, remove the dashboard and find the serial port on the odometer. The serial port is located in the back of the device. Attach a serial cable to the port for reprogramming, and reinstall the dashboard when finished.
To use the diagnostic method, access the vehicle's diagnostic port. This is typically used by mechanics as a gateway for computer diagnostics; however, it also has the power to disconnect and reset the odometer. While the direct and serial methods can be detected by shoddy work, the diagnostic method is undetectable.
Odometer tampering is illegal, and vehicle dealerships try their best to detect it. They look at other aspects of the vehicle to determine if the odometer reading is false. The tread of the tires, condition of the upholstery, and wear on the brake and gas pedal are examined. The vehicle's fluids can be pulled and analyzed for wear if necessary, and the vehicle's inspection and emissions history is also reviewed.