Why is the odometer not working?
2 Answers
Sensor failure, loose plugs, and circuit breaks can all cause the speedometer and odometer to stop working. There is another type of fault where either the speedometer or the odometer works alone, indicating an internal circuit or mechanical issue in the instrument. Detailed inspection or replacement of a new speedometer/odometer may be required. Below is a related introduction: Composition: The speedometer and odometer are actually composed of two gauges—one is the speedometer, and the other is the odometer. Traditional speedometers are mechanical, typically connected via a flexible shaft containing a steel cable. The other end of the flexible shaft connects to a gear in the transmission. The rotation of the gear drives the steel cable, which in turn rotates a magnet inside the odometer's housing. The housing is linked to the pointer, which is set to zero by a hairspring. Overview: The odometer is a digital instrument where the transmission gear of the counter drum meshes with the worm gear on the speedometer's drive shaft, causing the counter drum to rotate. Its characteristic is that when the upper drum completes one full rotation, the lower drum rotates 1/10 of a turn. Like the speedometer, the odometer also has an electronic version, which obtains mileage signals from the speed sensor. The accumulated mileage data in an electronic odometer is stored in non-volatile memory, preserving the data even when power is lost.
I've been repairing cars for over a decade, and when the odometer stops working, sensor failure is the most dreaded issue. The speed sensor is typically located on the transmission. If it gets clogged with sludge or fails completely, the dashboard won't receive pulse signals. Wiring problems are also common—rodents chewing through the wiring harness or loose connectors can interrupt the signal. Last time, I encountered an old Bora where the dashboard motherboard burned out, causing the odometer to stop counting—in such cases, the only solution is to dismantle the dashboard for repairs. I recommend first reading the fault codes to pinpoint the issue before rushing to replace parts. Before transferring ownership of a used car, pay special attention to whether the odometer functions properly to avoid future disputes.
